研究者詳細 - 髙橋　卓

論文 - 髙橋　卓

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Specific enhancement of the translation of thermospermine-responsive uORF-containing mRNAs by ribosomal mutations in Arabidopsis thaliana 査読

Koki Mutsuda, Yuichi Nishii, Tomohiko Toyoshima, Hiroko Fukushima, Hiroyasu Motose, Taku Takahashi

Plant Signaling & Behavior 2025年12月

Involvement of a NIMA-related kinase in cell division of the liverwort Marchantia polymorpha 査読

Hikari Mase, Aoi Sumiura, Yoshihiro Yoshitake, Takayuki Kohchi, Taku Takahashi, Hiroyasu Motose

Plant And Cell Physiology 2025年5月

ATML1 and PDF2 regulate cuticle formation and protect the plant body from environmental stresses in Arabidopsis thaliana seedlings 査読

Kenji Nagata, Ichiro Maekawa, Taku Takahashi, Mitsutomo Abe

Journal of Plant Research 2025年3月

Effect of environmental conditions on seed germination and seedling growth in Cuscuta campestris

Koki Nagao, Taku Takahashi, Ryusuke Yokoyama

2024年6月

Thermospermine Is an Evolutionarily Ancestral Phytohormone Required for Organ Development and Stress Responses in Marchantia Polymorpha. 査読

Takuya Furumoto, Shohei Yamaoka, Takayuki Kohchi, Hiroyasu Motose, Taku Takahashi

Plant & cell physiology 65 ( 3 ) 460 - 471 2024年4月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Thermospermine suppresses auxin-inducible xylem differentiation, whereas its structural isomer, spermine, is involved in stress responses in angiosperms. The thermospermine synthase, ACAULIS5 (ACL5), is conserved from algae to land plants, but its physiological functions remain elusive in non-vascular plants. Here, we focused on MpACL5, a gene in the liverwort Marchantia polymorpha, that rescued the dwarf phenotype of the acl5 mutant in Arabidopsis. In the Mpacl5 mutants generated by genome editing, severe growth retardation was observed in the vegetative organ, thallus, and the sexual reproductive organ, gametangiophore. The mutant gametangiophores exhibited remarkable morphological defects such as short stalks, fasciation and indeterminate growth. Two gametangiophores fused together, and new gametangiophores were often initiated from the old ones. Furthermore, Mpacl5 showed altered responses to heat and salt stresses. Given the absence of spermine in bryophytes, these results suggest that thermospermine has a dual primordial function in organ development and stress responses in M. polymorpha. The stress response function may have eventually been assigned to spermine during land plant evolution.

DOI： 10.1093/pcp/pcae002

Microtubule-associated proteins WDL5 and WDL6 play a critical role in pollen tube growth in Arabidopsis thaliana 査読

Takashi Okamoto, Hiroyasu Motose, Taku Takahashi

Plant Signaling & Behavior 18 ( 1 ) 2023年11月

Suppression of the dwarf phenotype of an Arabidopsis mutant defective in thermospermine biosynthesis by a synonymous codon change in the SAC51 uORF. 査読国際誌

Yuichi Nishii, Daiki Koyama, Hiroko Fukushima, Taku Takahashi

Molecular genetics and genomics : MGG 2023年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Thermospermine plays a critical role in negatively regulating xylem development in angiosperms. A mutant of Arabidopsis thaliana that is defective in thermospermine biosynthesis, acaulis5 (acl5), exhibits a dwarf phenotype with excessive xylem formation. Mechanistically thermospermine acts in attenuating the inhibitory effect of an evolutionarily conserved upstream open reading frame (uORF) on the main ORF of SAC51, which encodes a basic helix-loop-helix protein involved in xylem repression. Here, we revealed that a semidominant suppressor of acl5, sac503, which partially restores the acl5 phenotype, has a point mutation in the conserved uORF of SAC51 with no amino acid substitution in the deduced peptide sequence. In transgenic lines carrying the β-glucuronidase (GUS) reporter gene fused with the SAC51 5' region containing the uORF, the mutant construct was shown to confer higher GUS activity than does the wild-type SAC51 construct. We confirmed that sac503 mRNA was more stable than SAC51 mRNA in acl5. These results suggest that the single-base change in sac503 positively affects the translation of its main ORF instead of thermospermine. We further found that the uORF-GUS fusion protein could be synthesized in planta from the wild-type and sac503 translational fusion constructs.

DOI： 10.1007/s00438-023-02076-4

Loss of function of an Arabidopsis homologue of JMJD6 suppresses the dwarf phenotype of acl5, a mutant defective in thermospermine biosynthesis. 査読国際誌

Hirotoshi Matsuo, Hiroko Fukushima, Shinpei Kurokawa, Eri Kawano, Takashi Okamoto, Hiroyasu Motose, Taku Takahashi

FEBS letters 596 ( 23 ) 3005 - 3014 2022年12月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In Arabidopsis thaliana, the ACL5 gene encodes thermospermine synthase and its mutant, acl5, exhibits a dwarf phenotype with excessive xylem formation. Studies of suppressor mutants of acl5 reveal the involvement of thermospermine in enhancing mRNA translation of the SAC51 gene family. We show here that a mutant, sac59, which partially suppresses the acl5 phenotype, has a point mutation in JMJ22 encoding a D6-class Jumonji C protein (JMJD6). A T-DNA insertion allele, jmj22-2, also partially suppressed the acl5 phenotype while mutants of its closest two homologs JMJ21 and JMJ20 had no such effects, suggesting a unique role for JMJ22 in plant development. We found that mRNAs of the SAC51 family are more stabilized in acl5 jmj22-2 than in acl5.

DOI： 10.1002/1873-3468.14470

RNA processing/modifying enzymes play key roles in the response to thermospermine in Arabidopsis thaliana

Takahiro Tanaka, Daiki Koyama, Mitsuru Saraumi, Hiroyasu Motose, Taku Takahashi

bioRxiv 2022年9月

担当区分：責任著者出版者・発行元：Cold Spring Harbor Laboratory

Abstract

Thermospermine acts in negative regulation of xylem differentiation through enhancing mRNA translation of the members of the SAC51 gene family in Arabidopsis. These mRNAs contain conserved upstream open-reading-frames (uORFs) that are inhibitory to the main ORF translation. To address the mode of action of thermospermine in this process, we have isolated mutants that are insensitive to thermospermine, named its. We show here that four genes responsible for the mutants, its1 to its4, encode a homologue of SPOUT RNA methyl transferase, an rRNA pseudouridine synthase CBF5/NAP57, a putative spliceosome disassembly factor STIPL1/NTR1, and a plant-specific RNA-binding protein PHIP1, respectively. While these mutants except its1 are almost normal in appearance, they enhance the dwarf phenotype of a mutant of ACL5 defective in thermospermine biosynthesis, resulting in tiny-sized plants reminiscent of a double knockout of ACL5 and SACL3, a member of the SAC51 family. We confirmed that the GUS reporter activity from the SAC51 5’-GUS fusion transcript was severely reduced in all of these mutants. These results unveil the importance of RNA processing and modification for the translation of transcripts containing regulatory uORFs.

DOI： 10.1101/2022.09.19.508594

Establishment and application of novel culture methods in Marchantia polymorpha: persistent tip growth is required for substrate penetration by rhizoids 招待査読

Hikari Mase, Hirofumi Nakagami, Takashi Okamoto, Taku Takahashi, Hiroyasu Motose

Commun.Integr. Biol. 15 164 - 167 2022年

Plant specific armadillo repeat kinesin directs organelle transport and microtubule convergence to promote tip growth

Asaka Kanda, Kento Otani, Taku Takahashi, Hiroyasu Motose

bioRxiv 2022年

出版者・発行元：Cold Spring Harbor Laboratory

Abstract

Tip growth is essential for plant growth and reproduction. However, it remains elusive how highly polarized tip-growing cells coordinate the organization of intracellular components. Here, we show that plant-specific armadillo-repeat containing kinesin, MpARK, mediates organelle transport and microtubule convergence in tip growing rhizoids in the early diverging land plantMarchantia polymorpha. MpARK is required for anterograde transport of organelles to maintain their position. Furthermore, MpARK participates in the formation of microtubule foci at the rhizoid apex to stabilize growth direction. MpARK-dependent rhizoid growth is essential for plant anchorage and soil holding capacity. Thus, ARK might be a principal organelle transporter and intracellular organizer in the primitive rooting cells for the adaptation to terrestrial environments. Our findings suggest that ARK is functionally comparable to canonical anterograde kinesins in animals and fungi.

DOI： 10.1101/2022.07.08.499237

Responses of Polyamine-Metabolic Genes to Polyamines and Plant Stress Hormones in Arabidopsis Seedlings 査読

Yusaku Yariuchi, Takashi Okamoto, Yoshiteru Noutoshi, Taku Takahashi

Cells 10 ( 12 ) 3283 - 3283 2021年11月

担当区分：最終著者,　責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

In plants, many of the enzymes in polyamine metabolism are encoded by multiple genes, whose expressions are differentially regulated under different physiological conditions. For comprehensive understanding of their regulation during the seedling growth stage, we examined the expression of polyamine metabolic genes in response to polyamines and stress-related plant hormones in Arabidopsis thaliana. While confirming previous findings such as induction of many of the genes by abscisic acid, induction of arginase genes and a copper amine oxidase gene, CuAOα3, by methyl jasmonate, that of an arginine decarboxylase gene, ADC2, and a spermine synthase gene, SPMS, by salicylic acid, and negative feedback regulation of thermospermine biosynthetic genes by thermospermine, our results showed that expressions of most of the genes are not responsive to exogenous polyamines. We thus examined expression of OsPAO6, which encodes an apoplastic polyamine oxidase and is strongly induced by polyamines in rice, by using the promoter-GUS fusion in transgenic Arabidopsis seedlings. The GUS activity was increased by treatment with methyl jasmonate but neither by polyamines nor by other plant hormones, suggesting a difference in the response to polyamines between Arabidopsis and rice. Our results provide a framework to study regulatory modules directing expression of each polyamine metabolic gene.

DOI： 10.3390/cells10123283

植物ポリアミンの代謝と機能招待査読

高橋卓, 本瀬宏康

化学と生物 59 ( 6 ) 290 - 297 2021年6月

Distinct functions of ethylene and ACC in the basal land plant marchantia polymorpha. 査読

Asuka Katayose, Asaka Kanda, Yasutaka Kubo, Taku Takahashi, Hiroyasu Motose

Plant & cell physiology 2021年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

Ethylene is a gaseous phytohormone involved in various physiological processes including fruit ripening, senescence, root hair development, and stress responses. Recent genomics have suggested that most homologous genes of ethylene biosynthesis and signaling are conserved from algae to angiosperms, whereas function and biosynthesis of ethylene remain unknown in basal plants. Here, we examined physiological effects of ethylene, an ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), and an inhibitor of ethylene perception, silver thiosulfate (STS), in a basal land plant Marchantia polymorpha. M. polymorpha plants biosynthesized ethylene and treatment with high concentrations of ACC slightly promoted ethylene production. ACC remarkably suppressed growth of thalli (vegetative organs) and rhizoids (root-hair-like cells), whereas exogenous ethylene slightly promoted thallus growth. STS suppressed thallus growth and induced ectopic rhizoid formation on the dorsal surface of thalli. Thus, ACC and ethylene have different effects on vegetative growth of M. polymorpha. We generated single and double mutants of ACC synthase-like (ACSL) genes, MpACSL1 and MpACSL2. They did not show obvious defects in thallus growth, ACC content, and ethylene production, indicating that MpACSL genes are not essential for the vegetative growth and the biosynthesis of ACC and ethylene. The gene expression analysis suggested involvement of MpACSL1 and MpACSL2 in stress responses. Collectively, our results imply ethylene-independent function of ACC and the absence of ACC-mediated ethylene biosynthesis in M. polymorpha.

DOI： 10.1093/pcp/pcab042

The root growth reduction in response to mechanical stress involves ethylene-mediated microtubule reorganization and transmembrane receptor-mediated signal transduction in Arabidopsis. 査読国際誌

Takashi Okamoto, Shogo Takatani, Hiroyasu Motose, Hidetoshi Iida, Taku Takahashi

Plant cell reports 40 ( 3 ) 575 - 582 2021年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

KEY MESSAGE: We found that mutations in a Ca2+-permeable mechanosensitive channel MCA1, an ethylene-regulated microtubule-associated protein WDL5, and a versatile co-receptor BAK1 affect root growth response to mechanical stress. Plant root tips exposed to mechanical impedance show a temporal reduction in the elongation growth. The process involves a transient Ca2+ increase in the cytoplasm followed by ethylene signaling. To dissect the molecular mechanisms underlying this response, we examined the root growth of a series of Arabidopsis mutants with potentially altered response to mechanical stress after transfer from vertical to horizontal plates that were covered by dialysis membrane as an impedance. Among the plant hormone-response mutants tested, the ethylene-insensitive mutant ein3 was confirmed to show no growth reduction after the transfer. The root growth reduction was attenuated in a mutant of MCA1 encoding a Ca2+-permeable mechanosensitive channel and that of WDL5 encoding an ethylene-regulated microtubule-associated protein. We also found that the growth reduction was enhanced in a mutant of BAK1 encoding a co-receptor that pairs with numerous leucine-rich repeat receptor kinases to modulate growth and immunity. These results suggest the root growth reduction in response to mechanical stress involves ethylene-mediated microtubule reorganization and also transmembrane receptor-mediated signal transduction.

DOI： 10.1007/s00299-020-02653-6

Ceramides mediate positional signals in Arabidopsis thaliana protoderm differentiation. 査読国際誌

Kenji Nagata, Toshiki Ishikawa, Maki Kawai-Yamada, Taku Takahashi, Mitsutomo Abe

Development (Cambridge, England) 148 ( 2 ) 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

The differentiation of distinct cell types in appropriate patterns is a fundamental process in the development of multicellular organisms. In Arabidopsis thaliana, protoderm/epidermis differentiates as a single cell layer at the outermost position. However, little is known about the molecular nature of the positional signals that achieve correct epidermal cell differentiation. Here, we propose that very-long-chain fatty acid-containing ceramides (VLCFA-Cers) mediate positional signals by stimulating the function of ARABIDOPSIS THALIANA MERISTEM LAYER1 (ATML1), a master regulator of protoderm/epidermis differentiation, during lateral root development. We show that VLCFA-Cers, which are synthesized predominantly in the outermost cells, bind to the lipid-binding domain of ATML1. Importantly, this cell type-specific protein-lipid association alters the activity of ATML1 protein and consequently restricts its expression to the protoderm/epidermis through a transcriptional feedback loop. Furthermore, establishment of a compartment, enriched with VLCFA-containing sphingolipids, at the outer lateral membrane facing the external environment may function as a determinant of protodermal cell fate. Taken together, our results indicate that VLCFA-Cers play a pivotal role in directing protoderm/epidermis differentiation by mediating positional signals to ATML1.This article has an associated 'The people behind the papers' interview.

DOI： 10.1242/dev.194969

Easy-to-Use InDel Markers for Genetic Mapping between Col-0 and Ler-0 Accessions of Arabidopsis thaliana. 査読国際誌

Takahiro Tanaka, Yuichi Nishii, Hirotoshi Matsuo, Taku Takahashi

Plants (Basel, Switzerland) 9 ( 6 ) 2020年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Map-based gene cloning has played a key role in many genetic studies using the model plant, Arabidopsis thaliana. In the post- next generation sequencing era, identification of point mutations and their corresponding genes is increasingly becoming a powerful and important approach to define plant gene function. To perform initial mapping experiments efficiently on Arabidopsis mutants, enrichment of easy-to-use and reliable polymorphic DNA markers would be desirable. We present here a list of InDel polymorphic markers between Col-0 and Ler-0 accessions that can be detected in standard agarose gel electrophoresis.

DOI： 10.3390/plants9060779

Chemical Synthesis and Biological Effect on Xylem Formation of Xylemin and Its Analogues 査読

Hiroyoshi Takamura, Hiroyasu Motose, Taichi Otsu, Shiori Shinohara, Ryugo Kouno, Isao Kadota, Taku Takahashi

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2020 ( 18 ) 2745 - 2753 2020年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

Xylemin (6) and its designed structural analogues 18-23, N-(4-aminobutyl)alkylamines, were synthesized by 2-nitrobenzenesulfonamide (Ns) strategy. Investigation of the improved synthesis of 20-23 resulted in the development of one-step synthesis of these analogues from the commercially available corresponding ketones. Biological assessment of the synthetic molecules elucidated that xylemin (6) and the analogue N-(4-aminobutyl)cyclopentylamine (21) promoted the expression level of thermospermine synthase ACAULIS5 (ACL5) and enhanced xylem formation. In addition, xylemin (6) was found to significantly promote lateral root formation, whereas xylemin analogues 18-23 including 21 did not. These results indicate that the analogue 21 has the potential as a novel inhibitor of thermospermine synthesis to work specifically in xylem differentiation.

DOI： 10.1002/ejoc.202000322

Plant Polyamines. 国際誌

Taku Takahashi

Plants (Basel, Switzerland) 9 ( 4 ) 2020年4月

記述言語：英語

Polyamines are small organic compounds found in all living organisms. According to the high degree of positive charge at physiological pH, they interact with negatively charged macromolecules, such as DNA, RNA, and proteins, and modulate their activities. In plants, polyamines, some of which are presented as a conjugated form with cinnamic acids and proteins, are involved in a variety of physiological processes. In recent years, the study of plant polyamines, such as their biosynthetic and catabolic pathways and the roles they play in cellular processes, has flourished, becoming an exciting field of research. There is accumulating evidence that polyamine oxidation, the main catabolic pathway of polyamines, may have a potential role as a source of hydrogen peroxide. The papers in this Special Issue highlight new discoveries and research in the field of plant polyamine biology. The information will help to stimulate further research and make readers aware of the link between their own work and topics related to polyamines.

DOI： 10.3390/plants9040511

Microtubule Response to Tensile Stress Is Curbed by NEK6 to Buffer Growth Variation in the Arabidopsis Hypocotyl. 査読国際誌

Shogo Takatani, Stéphane Verger, Takashi Okamoto, Taku Takahashi, Olivier Hamant, Hiroyasu Motose

Current biology : CB 2020年3月

記述言語：英語

Growth variability generates mechanical conflicts in tissues. In plants, cortical microtubules usually align with maximal tensile stress direction, thereby mechanically reinforcing cell walls, and channeling growth rate and direction. How this is achieved remains largely unknown and likely involves microtubule regulators. The NIMA-related microtubule-associated kinase NEK6 phosphorylates tubulin, leading to the depolymerization of a subset of microtubules. We found that cortical microtubules exhibit a hyper-response to mechanical stress in the nek6 mutant. This response contributes to local cell protrusions in slow-growing regions of the nek6 mutant hypocotyl. When growth amplitude is higher, the hyper-alignment of microtubules leads to variable, stop-and-go, phenotypes, resulting in wavy hypocotyl shapes. After gravistimulation or touch, the nek6 mutant also exhibits a hyperbent hypocotyl phenotype, consistent with an enhanced perception of its own deformation. Strikingly, we find that NEK6 exhibits a novel form of polarity, being recruited at the ends of a subset of microtubules at cell edges. This pattern can be modified after local ablation, matching the new maximal tensile stress directions. We propose that NEK6 depolymerizes cortical microtubules that best align with maximal tensile stress to generate a noisier network of microtubules. This prevents an overreaction of microtubules to growth fluctuations and, instead, promotes the buffering of growth variations.

DOI： 10.1016/j.cub.2020.02.024

Salt hypersensitivity is associated with excessive xylem development in a thermospermine‐deficient mutant of Arabidopsis thaliana 査読

Shiori Shinohara, Takashi Okamoto, Hiroyasu Motose, Taku Takahashi

The Plant Journal 100 ( 2 ) 374 - 383 2019年10月

Ethylene signaling plays a pivotal role in mechanical stress-induced root growth cessation in Arabidopsis thaliana. 査読

Takashi Okamoto, Taku Takahashi

Plant Signaling and Behavior 2019年9月

Effect of Thermospermine on the Growth and Expression of Polyamine-Related Genes in Rice Seedlings 査読

Minaho Miyamoto, Satoshi Shimao, Wurina Tong, Hiroyasu Motose, Taku Takahashi

Plants 8 ( 8 ) 269 - 269 2019年8月

担当区分：最終著者,　責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

A mutant defective in the biosynthesis of thermospermine, acaulis5 (acl5), shows a dwarf phenotype with excess xylem vessels in Arabidopsis thaliana. Exogenous supply of thermospermine remarkably represses xylem differentiation in the root of seedlings, indicating the role of thermospermine in proper repression of xylem differentiation. However, the effect of thermospermine has rarely been investigated in other plant species. In this paper, we examined its effect on the growth and gene expression in rice seedlings. When grown with thermospermine, rice seedlings had no clearly enlarged metaxylem vessels in the root. Expression of OsACL5 was reduced in response to thermospermine, suggesting a negative feedback control of thermospermine biosynthesis like in Arabidopsis. Unlike Arabidopsis, however, rice showed up-regulation of phloem-expressed genes, OsHB5 and OsYSL16, by one-day treatment with thermospermine. Furthermore, expression of OsPAO2 and OsPAO6, encoding extracellular polyamine oxidase whose orthologs are not present in Arabidopsis, was induced by both thermospermine and spermine. These results suggest that thermospermine affects the expression of a subset of genes in rice different from those affected in Arabidopsis.

DOI： 10.3390/plants8080269

Complexity and Conservation of Thermospermine-Responsive uORFs of SAC51 Family Genes in Angiosperms 査読

Soichi Ishitsuka, Mai Yamamoto, Minaho Miyamoto, Yoshitaka Kuwashiro, Akihiro Imai, Hiroyasu Motose, Taku Takahashi

Frontiers in Plant Science 10 2019年5月

Omeprazole Enhances Mechanical Stress-Induced Root Growth Reduction in Arabidopsis thaliana. 査読

Takashi Okamoto, Shogo Takatani, Yoshiteru Noutoshi, Hiroyasu Motose, Taku Takahashi

Plant & cell physiology 59 ( 8 ) 1581 - 1591 2018年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Mechanical sensing is one of the most fundamental processes for sessile plants to survive and grow. The response is known to involve calcium elevation in the cell. Arabidopsis seedlings grown horizontally on agar plates covered with a dialysis membrane show a 2-fold reduction in root growth compared with those grown vertically, a response to mechanical stress generated due to gravitropism of the root. To understand the molecular mechanism of how plant roots sense and respond to mechanical stimuli, we screened chemical libraries for compounds that affect the horizontal root growth in this experimental system and found that, while having no effect on root gravitropism, omeprazole known as a proton pump inhibitor significantly enhanced the mechanical stress-induced root growth reduction especially in lower pH media. In contrast, omeprazole reversed neither the alleviation of the mechanical stress-induced growth reduction caused by calcium depletion nor the insensitivity to the mechanical stress in the ethylene signaling mutant ein2. Together with the finding that omeprazole increased expression of touch-induced genes and ETHYLENE RESPONSE FACTOR1, our results suggest that the target of omeprazole mediates ethylene signaling in the root growth response to mechanical stress.

DOI： 10.1093/pcp/pcy131

An evolutionarily conserved NIMA-related kinase directs rhizoid tip growth in the basal land plant Marchantia polymorpha. 査読国際誌

Kento Otani, Kimitsune Ishizaki, Ryuichi Nishihama, Shogo Takatani, Takayuki Kohchi, Taku Takahashi, Hiroyasu Motose

Development (Cambridge, England) 145 ( 5 ) 2018年3月

記述言語：英語

Tip growth is driven by turgor pressure and mediated by the polarized accumulation of cellular materials. How a single polarized growth site is established and maintained is unclear. Here, we analyzed the function of NIMA-related protein kinase 1 (MpNEK1) in the liverwort Marchantia polymorpha In the wild type, rhizoid cells differentiate from the ventral epidermis and elongate through tip growth to form hair-like protrusions. In Mpnek1 knockout mutants, rhizoids underwent frequent changes in growth direction, resulting in a twisted and/or spiral morphology. The functional MpNEK1-Citrine protein fusion localized to microtubule foci in the apical growing region of rhizoids. Mpnek1 knockouts exhibited increases in both microtubule density and bundling in the apical dome of rhizoids. Treatment with the microtubule-stabilizing drug taxol phenocopied the Mpnek1 knockout. These results suggest that MpNEK1 directs tip growth in rhizoids through microtubule organization. Furthermore, MpNEK1 expression rescued ectopic outgrowth of epidermal cells in the Arabidopsis thaliana nek6 mutant, strongly supporting an evolutionarily conserved NEK-dependent mechanism of directional growth. It is possible that such a mechanism contributed to the evolution of the early rooting system in land plants.

DOI： 10.1242/dev.154617

Thermospermine: An evolutionarily ancient but functionally new compound in plants 査読

Taku Takahashi

Methods in Molecular Biology 1694 51 - 59 2018年

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：Humana Press Inc.

Themospermine is a structural isomer of spermine and is present in some bacteria and most of plants. An Arabidopsis mutant, acaulis5 (acl5), that is defective in the biosynthesis of thermospermine displays excessive proliferation of xylem vessels with dwarfed growth. Recent studies using acl5 and its suppressor mutants that recover the growth without thermospermine have revealed that thermospermine plays a key role in the negative control of the proliferation of xylem vessels through enhancing translation of specific mRNAs that contain a conserved upstream open-reading-frame (uORF) in the 50 leader region.

DOI： 10.1007/978-1-4939-7398-9_4

Detection of thermospermine and spermine by HPLC in plants 査読

Taku Takahashi, Ayaka Takano, Jun-Ichi Kakehi

Methods in Molecular Biology 1694 69 - 73 2018年

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：Humana Press Inc.

Thermospermine, a structural isomer of spermine, is widely spread in the plant kingdom and has recently been shown to play a key role in the repression of xylem differentiation in vascular plants. However, a standard high-performance liquid chromatography (HPLC) protocol for detecting polyamines as their dansyl derivative cannot distinguish themospermine from spermine. These isomers become separated from each other after benzoylation. In this chapter, we describe a simple protocol for extraction, benzoylation, and HPLC detection of thermospermine and spermine with other polyamines from plant material.

DOI： 10.1007/978-1-4939-7398-9_6

Directional cell expansion requires NIMA-related kinase 6 (NEK6)-mediated cortical microtubule destabilization 査読

Shogo Takatani, Shinichiro Ozawa, Noriyoshi Yagi, Takashi Hotta, Takashi Hashimoto, Yuichiro Takahashi, Taku Takahashi, Hiroyasu Motose

SCIENTIFIC REPORTS 7 7826 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Plant cortical microtubules align perpendicular to the growth axis to determine the direction of cell growth. However, it remains unclear how plant cells form well-organized cortical microtubule arrays in the absence of a centrosome. In this study, we investigated the functions of Arabidopsis NIMA-related kinase 6 (NEK6), which regulates microtubule organization during anisotropic cell expansion. Quantitative analysis of hypocotyl cell growth in the nek6-1 mutant demonstrated that NEK6 suppresses ectopic outgrowth and promotes cell elongation in different regions of the hypocotyl. Loss of NEK6 function led to excessive microtubule waving and distortion, implying that NEK6 suppresses the aberrant cortical microtubules. Live cell imaging showed that NEK6 localizes to the microtubule lattice and to the shrinking plus and minus ends of microtubules. In agreement with this observation, the induced overexpression of NEK6 reduced and disorganized cortical microtubules and suppressed cell elongation. Furthermore, we identified five phosphorylation sites in beta-tubulin that serve as substrates for NEK6 in vitro. Alanine substitution of the phosphorylation site Thr166 promoted incorporation of mutant beta-tubulin into microtubules. Taken together, these results suggest that NEK6 promotes directional cell growth through phosphorylation of beta-tubulin and the resulting destabilization of cortical microtubules.

DOI： 10.1038/s41598-017-08453-5

Editorial: Molecular Mechanisms Underlying Polyamine Functions in Plants 査読

Patrick H. Masson, Taku Takahashi, Riccardo Angelini

FRONTIERS IN PLANT SCIENCE 8 ( 14 ) 2017年1月

TLCを用いた簡便なポリアミン検出

高橋卓, 懸樋潤一, 今井章裕

ポリアミン 4 ( 1 ) 14 - 16 2017年

Thermospermine enhances translation of SAC51 and SACL1 in Arabidopsis 査読

Mai Yamamoto, Taku Takahashi

PLANT SIGNALING & BEHAVIOR 12 ( 1 ) 414 - 421 2017年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：TAYLOR & FRANCIS INC

The excessive xylem phenotype of acaulis5 (acl5), an Arabidopsis mutant defective in the synthesis of thermospermine, indicates that thermospermine is required for negative regulation of xylem differentiation. SAC51 was identified from a dominant suppressor of acl5, sac51-d, and encodes a basic helix-loop-helix (bHLH) protein. sac51-d has a premature termination codon in one of upstream open-reading frames (uORFs) of the SAC51 mRNA that is conserved among the SAC51 family members. Thermospermine may act to bypass the inhibitory effect of the uORF on main ORF translation. Another suppressor, sac57-d, also has a mutation in the conserved uORF of SACL3, a member of the SAC51 family. On the other hand, the double knockout of SAC51 and SACL3 is insensitive to thermospermine, suggesting their key role in the response to thermospermine. However, we found that thermospermine enhances mRNA translation of SAC51 and SACL1 but not of SACL2 and SACL3. Taken together with recent findings from other groups, we propose a mechanism by which thermospermine diffused from xylem precursor cells acts non-cell-autonomously to restrict their proliferation.

DOI： 10.1080/15592324.2016.1276685

The SAC51 Family Plays a Central Role in Thermospermine Responses in Arabidopsis 査読

Qingqing Cai, Hiroko Fukushima, Mai Yamamoto, Nami Ishii, Tomoaki Sakamoto, Tetsuya Kurata, Hiroyasu Motose, Taku Takahashi

PLANT AND CELL PHYSIOLOGY 57 ( 8 ) 1583 - 1592 2016年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

The acaulis5 (acl5) mutant of Arabidopsis thaliana is defective in the biosynthesis of thermospermine and shows a dwarf phenotype associated with excess xylem differentiation. SAC51 was identified from a dominant suppressor of acl5, sac51-d, and encodes a basic helix-loop-helix protein. The sac51-d mutant has a premature termination codon in an upstream open reading frame (uORF) that is conserved among all four members of the SAC51 family, SAC51 and SACL1-SACL3. This suggests that thermospermine cancels the inhibitory effect of the uORF in main ORF translation. Another suppressor, sac57-d, has a mutation in the conserved uORF of SACL3. To define further the function of the SAC51 family in the thermospermine response, we analyzed T-DNA insertion mutants of each gene. Although sacl1-1 may not be a null allele, the quadruple mutant showed a semi-dwarf phenotype but with an increased level of thermospermine and decreased sensitivity to exogenous thermospermine that normally represses xylem differentiation. The sac51-1 sacl3-1 double mutant was also insensitive to thermospermine. These results suggest that SAC51 and SACL3 play a key role in thermospermine-dependent negative control of thermospermine biosynthesis and xylem differentiation. Using 5' leader-GUS (beta-glucuronidase) fusion constructs, however, we detected a significant enhancement of the GUS activity by thermospermine only in SAC51 and SACL1 constructs. Furthermore, while acl5-1 sac51-1 showed the acl5 dwarf phenotype, acl5-1 sacl3-1 exhibited an extremely tiny-plant phenotype. These results suggest a complex regulatory network for the thermospermine response in which SAC51 and SACL3 function in parallel pathways.

DOI： 10.1093/pcp/pcw113

Polyamine Resistance Is Increased by Mutations in a Nitrate Transporter Gene NRT1.3 (AtNPF6.4) in Arabidopsis thaliana 査読

Wurina Tong, Akihiro Imai, Ryo Tabata, Shuji Shigenobu, Katsushi Yamaguchi, Masashi Yamada, Mitsuyasu Hasebe, Shinichiro Sawa, Hiroyasu Motose, Taku Takahashi

FRONTIERS IN PLANT SCIENCE 7 ( 834 ) 2016年6月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：FRONTIERS MEDIA SA

Polyamines are small basic compounds present in all living organisms and act in a variety of biological processes. However, the mechanism of polyamine sensing, signaling and response in relation to other metabolic pathways remains to be fully addressed in plant cells. As one approach, we isolated Arabidopsis mutants that show increased resistance to spermine in terms of chlorosis. We show here that two of the mutants have a point mutation in a nitrate transporter gene of the NRT1/PTR family (NPF), NRT1.3 (AtNPF6.4). These mutants also exhibit increased resistance to putrescine and spermidine while loss-of-function mutants of the two closest homologs of NRT1.3, root-specific NRT1.1 (AtNPF6.3) and petiole-specific NRT1.4 (AtNPF6.2), were shown to have a normal sensitivity to polyamines. When the GUS reporter gene was expressed under the control of the NRT1.3 promoter, GUS staining was observed in leaf mesophyll cells and stem cortex cells but not in the epidermis, suggesting that NRT1.3 specifically functions in parenchymal tissues. We further found that the aerial part of the mutant seedling has normal levels of polyamines but shows reduced uptake of norspermidine compared with the wild type. These results suggest that polyamine transport or metabolism is associated with nitrate transport in the parenchymal tissue of the shoot.

DOI： 10.3389/fpls.2016.00834

Chemical control of xylem differentiation by thermospermine, xylemin, and auxin 査読

Kaori Yoshimoto, Hiroyoshi Takamura, Isao Kadota, Hiroyasu Motose, Taku Takahashi

SCIENTIFIC REPORTS 6 ( 21487 ) 2016年2月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

The xylem conducts water and minerals from the root to the shoot and provides mechanical strength to the plant body. The vascular precursor cells of the procambium differentiate to form continuous vascular strands, from which xylem and phloem cells are generated in the proper spatiotemporal pattern. Procambium formation and xylem differentiation are directed by auxin. In angiosperms, thermospermine, a structural isomer of spermine, suppresses xylem differentiation by limiting auxin signalling. However, the process of auxin-inducible xylem differentiation has not been fully elucidated and remains difficult to manipulate. Here, we found that an antagonist of spermidine can act as an inhibitor of thermospermine biosynthesis and results in excessive xylem differentiation, which is a phenocopy of a thermospermine-deficient mutant acaulis5 in Arabidopsis thaliana. We named this compound xylemin owing to its xylem-inducing effect. Application of a combination of xylemin and thermospermine to wild-type seedlings negates the effect of xylemin, whereas co-treatment with xylemin and a synthetic proauxin, which undergoes hydrolysis to release active auxin, has a synergistic inductive effect on xylem differentiation. Thus, xylemin may serve as a useful transformative chemical tool not only for the study of thermospermine function in various plant species but also for the control of xylem induction and woody biomass production.

DOI： 10.1038/srep21487

サーモスペルミン／木部分化の鍵を握る低分子

高橋卓, 本瀬宏康

生物の科学遺伝 ( 9 ) 356 - 360 2016年

Structure, function, and evolution of plant NIMA-related kinases: Implication for phosphorylation-dependent microtubule regulation（共著）査読

S. Takatani, K. Otani, M. Kanazawa, T. Takahashi, H. Motose

J. Plant Res. 128 ( 6 ) 875 - 891 2015年11月

ATML1 and PDF2 play a redundant and essential role in Arabidopsis embryo development（共著）査読

E. Ogawa, Y. Yamada, N. Sezaki, S. Kosaka, H. Kondo, N. Kamata, M. Abe, Y. Komeda, T. Takahashi

Plant Cell Physiol. 56 ( 6 ) 1183 - 1192 2015年6月

Abscisic acid induces ectopic outgrowth in epidermal cells through cortical microtubule reorganization in Arabidopsis thaliana（共著）査読

S. Takatani, T. Hirayama, T. Hashimoto, T. Takahashi, H. Motose

Sci. Rep. 5 11364 2015年6月

Regulation and diversity of polyamine biosynthesis in plants 査読

Taku Takahashi, Wurina Tong

Polyamines: A Universal Molecular Nexus for Growth, Survival, and Specialized Metabolism 27 - 44 2015年1月

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：Springer Japan

In higher plants, the main route for putrescine synthesis may be from arginine. Higher accumulation of putrescine under biotic and abiotic stress conditions is attributed at least in part to stress-inducible expression of arginine decarboxylase genes. Regulation of spermidine synthesis involves translational control of the S -adenosylmethionine decarboxylase mRNA, which is responsive to cellular polyamine levels. Genes encoding S -adenosylmethionine decarboxylase and spermine synthase are also responsive to environmental stimuli or show preferential expression in certain organs. Stress-inducible expression of these genes involves plant hormone signaling of abscisic acid (ABA) or methyl jasmonate (MeJA). Thermospermine synthase is widely distributed in the plant kingdom but has a unique role in the repression control of xylem differentiation in higher plants. Expression of the gene for thermospermine synthase is under negative feedback control by thermospermine. Putrescine, spermidine, and cadaverine are also essential precursors for alkaloid biosynthesis in some plant species. Polyamines occur in various aspects of plant growth as a conjugated form with cinnamic acids and proteins. Genes responsible for these conjugations have been increasingly identified.

DOI： 10.1007/978-4-431-55212-3_3

Mutations in ribosomal proteins, RPL4 and RACK1, suppress the phenotype of a thermospermine-deficient mutant of Arabidopsis thaliana（共著）査読

J. I. Kakehi, E. Kawano, K. Yoshimoto, Q. Cai, A. Imai, T. Takahashi

PLoS ONE 10 ( 1 ) e0117309 2015年1月

Thermospermine modulates expression of auxin-related genes in Arabidopsis（共著）査読

W. Tong, K. Yoshimoto, J.-I. Kakehi, H. Motose, M. Niitsu, T. Takahashi

Front. Plant Sci. 5 ( 94 ) 2014年3月

Allele-specific effects of PDF2 on floral morphology in Arabidopsis thaliana 査読

Naoko Kamata, Ayaka Sugihara, Yoshibumi Komeda, Taku Takahashi

Plant Signaling and Behavior 8 ( 12 ) 1 - 3 2014年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

The class IV Homeodomain-leucine zipper (HD-ZIP IV) gene family includes several genes that are functionally significant in epidermal development. Our recent study revealed that double mutants of the epidermis-expressed HD-ZIP IV members, PROTODERMAL FACTOR2 (PDF2) in combination with some HOMEODOMAIN GLABROUS (HDG, pronounced "hedge") genes, affect stamen development and specification of petal and stamen identity, possibly in a non cell-autonomous manner. However, the effect of the pdf2 mutations on the floral development was largely different depending on T-DNA insertion locations: pdf2-1 hdg flowers exhibited homeotic conversion of petals and stamens, while pdf2-2 hdg flowers had only a reduced number of stamens. Here, we used 2 additional pdf2 alleles to make double mutants and found that their floral phenotypes were rather similar to those of pdf2-2 hdg. The allele-specific effect caused by pdf2-1, which carries a T-DNA in a steroidogenic acute regulatory protein-related lipid transfer (START) domainencoding region, suggests the importance of the START domain in proper function of HD-ZIP IV proteins. © 2014 Landes Bioscience.

DOI： 10.4161/psb.27417

Mutations in epidermis-specific HD-ZIP IV genes affect floral organ identity in Arabidopsis thaliana.（共著）査読

Kamata N, Okada H, Komeda Y, Takahashi T

The Plant Journal 75 ( 3 ) 430 - 440 2013年8月

Determination of polyamines in Arabidopsis thaliana by capillary electrophoresis using salicylaldehyde-5-sulfonate as a derivatizing reagent 査読

Genki Inoue, Takashi Kaneta, Toshio Takayanagi, Junichi Kakehi, Hiroyasu Motose, Taku Takahashi

ANALYTICAL METHODS 5 ( 11 ) 2854 - 2859 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Herein, we report a novel method for the determination of polyamines in a sample extracted from Arabidopsis thaliana by capillary electrophoresis (CE) using salicylaldehyde-5-sulfonate (SAS) as a derivatizing reagent. An aldehyde group of SAS forms a Schiff base with amino groups of aliphatic polyamines, resulting in an anionic species with an absorption band in the ultraviolet region. The derivatization method was straightforward since the derivatives were formed by mixing a sample with the derivatizing reagent at a neutral pH. In addition, the negative charges induced by SAS led to a high resolution with a short analysis time. This method permitted the separation of five polyamines, which play important roles in plants. However, further improvement in sensitivity was needed for the determination of the polyamines in plant samples. Therefore, the CE method was coupled with solid-phase extraction (SPE) using an ion-pairing formation with sodium dodecyl benzene sulfonate. The SPE method improved the concentration limits of detection to sub-mu M levels, which corresponded with a 10-fold enhancement. The calibration curves for cadaverine, putrescine, and spermidine were linear with concentrations that ranged from 1 to 20 mu M and correlation coefficients (R-2) were greater than 0.998. The proposed method was applied to the determination of spermidine in a plant sample, Arabidopsis thaliana.

DOI： 10.1039/c3ay26360f

NIMA-related kinases regulate directional cell growth and organ development through microtubule function in Arabidopsis thaliana.（共著）査読国際誌

Motose H, Takatani S, Ikeda T, Takahashi T

Plant Signaling Behavior 7 ( 12 ) 1552 - 5 2012年12月

Thermospermine suppresses auxin-inducible xylem differentiation in Arabidopsis thaliana. （共著）査読

Yoshimoto K, Noutoshi Y, Hayashi K, Shirasu K, Takahashi T, Motose H

Plant Signaling Behavior 7 ( 8 ) 937 - 939 2012年8月

Thermospermine is Not a Minor Polyamine in the Plant Kingdom 査読

Ayaka Takano, Jun-Ichi Kakehi, Taku Takahashi

PLANT AND CELL PHYSIOLOGY 53 ( 4 ) 606 - 616 2012年4月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

Thermospermine is a structural isomer of spermine, which is one of the polyamines studied extensively in the past, and is produced from spermidine by the action of thermospermine synthase encoded by a gene named ACAULIS5 (ACL5) in plants. According to recent genome sequencing analyses, ACL5-like genes are widely distributed throughout the plant kingdom. In Arabidopsis, ACL5 is expressed specifically during xylem formation from procambial cells to differentiating xylem vessels. Loss-of-function mutants of ACL5 display overproliferation of xylem vessels along with severe dwarfism, suggesting that thermospermine plays a role in the repression of xylem differentiation. Studies of suppressor mutants of acl5 that recover the wild-type phenotype in the absence of thermospermine suggest that thermospermine acts on the translation of specific mRNAs containing upstream open reading frames (uORFs). Thermospermine is a novel type of plant growth regulator and may also serve in the control of wood biomass production.

DOI： 10.1093/pcp/pcs019

A chemical biology approach reveals an opposite action between thermospermine and auxin inxylem development in Arabidopsis thaliana.（共著）査読

Yoshimoto K, Noutoshi Y, Hayashi K, Shirasu K, Takahashi T, Motose H

Plant and Cell Physiology 53 ( 4 ) 635 - 645 2012年4月

Key proliferative activity in the junction between the leaf blade and leaf petiole of Arabidopsis thaliana.（共著）査読

Ichihashi Y, Kawade K, Usami T, Horiguchi G, Takahashi T, Tsukaya H

Plant Physiology 157 ( 3 ) 1151 - 1162 2011年11月

NIMA-related kinases 6, 4, and 5 interact with each other to regulate microtubule organization during epidermal cell expansion in Arabidopsis thaliana.（共著）査読

Motose H, Hamada T, Yoshimoto K, Murata T, Hasebe M, Watanabe Y, Hashimoto T, Sakai T, Takahashi T

The Plant Journal 67 ( 6 ) 993 - 1005 2011年9月

Arabidopsis Qa-SNARE SYP2 proteins localized to different subcellular regions function redundantly in vacuolar protein sorting and plant development. （共著）査読

M. Shirakawa, H. Ueda, T. Shimada, Y. Koumoto, T.-L. Shimada, M. Kondo, T. Takahashi, Y. Okuyama, M. Nishimura, I. Hara-Nishimura

Plant J. 64 ( 6 ) 924 - 935 2010年12月

Norspermine substitutes for thermospermine in the control of stem elongation in Arabidopsis thaliana. （共著）査読

J.-I. Kakehi, Y. Kuwashiro, H. Motose, K. Igarashi, T. Takahashi

FEBS Lett. 584 ( 14 ) 3042 - 3046 2010年7月

Polyamines: Ubiquitous Polycations with Unique Roles in Growth and Stress Responses.（共著）査読

T. Takahashi, J.-I. Kakehi

Ann. Bot. 105 ( 1 ) 1 - 6 2010年1月

シロイヌナズナSYP2ファミリーSNAREタンパク質の機能解析

白川一, 上田晴子, 西山千晶, 嶋田知生, 河本恭子, 近藤真紀, 高橋卓, 西村幹夫, 西村いくこ

日本植物生理学会年会およびシンポジウム講演要旨集 2010 ( 0 ) 127 - 127 2010年

出版者・発行元：日本植物生理学会

シロイヌナズナゲノムには4種類のSYP2ファミリーSNAREタンパク質がコードされている．過去に，VAM3/SYP22 及びPEP12/SYP21の単独変異体は致死性を示すことが報告されている．しかしながら，我々はこれまで，vam3/syp22変異体を単離することに成功し，変異体の解析から，VAM3/SYP22が植物の成長・維管束パターンの形成・ミロシン細胞分化に関与していることを報告してきた．このことから，SYP2ファミリーの機能について再検証が必要であると考えられる．今回，我々はplp/syp23の変異体を確立することに成功し，加えて，vam3/syp22との多重変異体を作製した．さらに，artificial microRNAによる遺伝子抑制法により，vam3/syp22変異体背景でPEP12/SYP21の遺伝子発現を抑制することに成功した．これらの変異体の表現型の解析から，VAM3/SYP22，PEP12/SYP21，PLP/SYP23が冗長的に機能していることを発見した．興味深いことに，GFP融合タンパク質を用いた細胞内局在の解析により，PLP/SYP23が膜成分に局在することなくSNAREタンパク質として機能している可能性を見出した．そこで，本大会ではSYP2ファミリーの機能について議論したい．

DOI： 10.14841/jspp.2010.0.0127.0

Infrared laser-mediated local gene induction in medaka, zebrafish and Arabidopsis thaliana 査読

Tomonori Deguchi, Mariko Itoh, Hiroko Urawa, Tomohiro Matsumoto, Sohei Nakayama, Takashi Kawasaki, Takeshi Kitano, Shoji Oda, Hiroshi Mitani, Taku Takahashi, Takeshi Todo, Junichi Sato, Kiyotaka Okada, Kohei Hatta, Shunsuke Yuba, Yasuhiro Kamei

Development Growth and Differentiation 51 ( 9 ) 769 - 775 2009年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

Heat shock promoters are powerful tools for the precise control of exogenous gene induction in living organisms. In addition to the temporal control of gene expression, the analysis of gene function can also require spatial restriction. Recently, we reported a new method for in vivo, single-cell gene induction using an infrared laser-evoked gene operator (IR-LEGO) system in living nematodes (Caenorhabditis elegans). It was demonstrated that infrared (IR) irradiation could induce gene expression in single cells without incurring cellular damage. Here, we report the application of IR-LEGO to the small fish, medaka (Japanese killifish
Oryzias latipes) and zebrafish (Danio rerio), and a higher plant (Arabidopsis thaliana). Using easily observable reporter genes, we successfully induced gene expression in various tissues in these living organisms. IR-LEGO has the potential to be a useful tool in extensive research fields for cell/tissue marking or targeted gene expression in local tissues of small fish and plants. © 2009 Japanese Society of Developmental Biologists.

DOI： 10.1111/j.1440-169X.2009.01135.x

A semi-dominant mutation in a ribosomal protein L10 gene suppresses the dwarf phenotype of the acl5 mutant in Arabidopsis thaliana. （共著）査読

A. Imai, M. Komura, E. Kawano, Y. Kuwashiro, T. Takahashi

The Plant Journal 56 ( 6 ) 881 - 890 2008年12月

Thermospermine is required for stem elongation in Arabidopsis thaliana. （共著）査読

J.-I. Kakehi, Y. Kuwashiro, M. Niitsu, T. Takahashi

Plant and Cell Physiology 49 ( 9 ) 1342 - 1349 2008年9月

ミロシン細胞分化におけるSYP2ファミリーSNAREタンパク質の役割

上田晴子, 白川一, 西山千晶, 嶋田知生, 高橋卓, 西村いくこ

日本植物生理学会年会およびシンポジウム講演要旨集 2008 ( 0 ) 794 - 794 2008年

出版者・発行元：日本植物生理学会

ミロシン細胞はアブラナ科に特異的な異型細胞である．葉のミロシン細胞は主に維管束近傍に点在し，周囲の細胞に比べて顕著に伸張し分枝する場合もある．ミロシン細胞の液胞は発達しており，内部に蓄積されたミロシナーゼがグルコシノレート（カラシ油配糖体）を分解して辛み成分を生成することによって植物の生体防御に関与する．現在のところ，ミロシン細胞の分化機構は全く未知である．これまで，ミロシン細胞の数が増加して異常な分布パターンを示すatvam3変異体の解析から，ミロシン細胞と導管の分化が植物ホルモンによって制御されている可能性を報告してきた．AtVAM3は液胞膜と液胞前区画膜に局在するSYP2ファミリーに属するSNAREタンパク質である．シロイヌナズナにはAtVAM3以外に2つのSYP2タンパク質 (AtPEP12およびAtPLP) が存在することから，ミロシン細胞分化におけるこれらの関与を解析した．その結果，atpep12変異体およびatplp変異体では，ミロシン細胞の数と分布パターンに異常はなかった．atvam3変異体との多重変異体では，atvam3単独変異体よりもミロシン細胞分化において顕著な異常を示し，さらにatvam3単独変異体では見られなかった新たな表現型を持つことが明らかとなった．以上の結果から，SYP2ファミリーの機能について考察したい．

DOI： 10.14841/jspp.2008.0.0794.0

A protective role for the polyamine spermine against drought stress in Arabidopsis 査読

Koji Yamaguchi, Yoshihiro Takahashi, Thomas Berberich, Akihiko Imai, Taku Takahashi, Anthonv J. Michael, Tomonobu Kusano

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 352 ( 2 ) 486 - 490 2007年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

Cellular polyamine content often changes in response to abiotic stresses. However, its physiological relevance is unknown. We found that an Arabidopsis mutant plant (acl5lspms), which cannot produce spermine, is hypersensitive to high salt. Examination of drought sensitivity of the mutant and comparison with wild type plants indicated hypersensitivity to drought. This phenotype was cured by spermine pretreatment but not by the other polyamines putrescine and spermidine, suggesting that drought-hypersensitivity exhibited by the mutant is due to spermine deficiency. The water loss rate of wild type and mutant plants were similar until 20 min after onset of dehydration stress, but after a longer exposure the rate in mutant plants was higher than in wild type plants. Consistent with this result, the stomata of the mutant leaves remained open while in wild type leaves they closed. Based on the collected data, we discuss a role for spermine in response to drought stress. (c) 2006 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2006.11.041

The polyamine spermine protects against high salt stress in Arabidopsis thaliana 査読

Koji Yamaguchi, Yoshihiro Takahashi, Thomas Berberich, Akihiko Imai, Atsushi Miyazaki, Taku Takahashi, Anthony Michael, Tomonobu Kusano

FEBS LETTERS 580 ( 30 ) 6783 - 6788 2006年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

It is well known that changes in abiotic conditions such as the concentration of ions, temperature and humidity lead to modulation of polyamine contents in plants. However, little is known about the relevant parts these polyamines play in abiotic stress responses. Here we addressed a specific role of spermine during high salt stress using an Arabidopsis double knockoutmutant plant (acl5lspnrs) which cannot produce spermine. The mutant showed higher sensitivity to high salt than wild type plants. This phenotype was cured by exogenous spermine but not by the other polyamines putrescine and spermidine, suggesting a strong link between spermine-deficiency and NaCl-hypersensitivity. The mutant was also hypersensitive to high levels of KCl but not to MgCl2 or to high osmoticum. NaCl-hypersensitivity of the mutant was compromised by treatment with Ca2+ channel blockers. Moreover, the mutant showed poor growth on Ca2+-depleted Murashige-Skoog agar media. The data suggest that the absence of spermine causes an imbalance in Ca2+ homeostasis in the mutant plant. Based on the data obtained, we propose a model for a role of spermine in high salt stress responses. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.febslet.2006.10.078

The dwarf phenotype of the Arabidopsis acl5 mutant is suppressed by a mutation in an upstream ORF of a bHLH gene 査読

Akihiro Imai, Yoshie Hanzawa, Mio Komura, Kotaro T. Yamamoto, Yoshibumi Komeda, Taku Takahashi

DEVELOPMENT 133 ( 18 ) 3575 - 3585 2006年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：COMPANY OF BIOLOGISTS LTD

Loss-of-function mutants of the Arabidopsis thaliana ACAULIS 5 (ACL5) gene, which encodes spermine synthase, exhibit a severe dwarf phenotype. To elucidate the ACL5-mediated regulatory pathways of stem internode elongation, we isolated four suppressor of acaulis (sac) mutants that reverse the acl5 dwarf phenotype. Because these mutants do not rescue the dwarfism of known phytohormone-related mutants, the SAC genes appear to act specifically on the ACL5 pathways. We identify the gene responsible for the dominant sac51-d mutant, which almost completely suppresses the acl5 phenotype. sac51-d disrupts a short upstream open reading frame (uORF) of SAC51, which encodes a bHLH-type transcription factor. Our results indicate that premature termination of the uORF in sac51-d results in an increase in its own transcript level, probably as a result of an increased translation of the main ORF. We suggest a model in which ACL5 plays a role in the translational activation of SAC51, which may lead to the expression of a subset of genes required for stem elongation.

DOI： 10.1242/dev.02535

Characterization of the class IV homeodomain-leucine zipper gene family in Arabidopsis 査読

Miyuki Nakamura, Hiroshi Katsumata, Mitsutomo Abe, Naoto Yabe, Yoshibumi Komeda, Kotaro T. Yamamoto, Taku Takahashi

PLANT PHYSIOLOGY 141 ( 4 ) 1363 - 1375 2006年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC PLANT BIOLOGISTS

The Arabidopsis ( Arabidopsis thaliana) genome contains 16 genes belonging to the class IV homeodomain-Leucine zipper gene family. These include GLABRA2, ANTHOCYANINLESS2, FWA, ARABIDOPSIS THALIANA MERISTEM LAYER1 ( ATML1), and PROTODERMAL FACTOR2 (PDF2). Our previous study revealed that atml1 pdf2 double mutants have severe defects in the shoot epidermal cell differentiation. Here, we have characterized additional members of this gene family, which we designated HOMEODOMAIN GLABROUS1 (HDG1) through HDG12. Analyses of transgenic Arabidopsis plants carrying the gene-specific promoter fused to the bacterial beta-glucuronidase reporter gene revealed that some of the promoters have high activities in the epidermal layer of the shoot apical meristem and developing shoot organs, while others are temporarily active during reproductive organ development. Expression profiles of highly conserved paralogous gene pairs within the family were found to be not necessarily overlapping. Analyses of T-DNA insertion mutants of these HDG genes revealed that all mutants except hdg11 alleles exhibit no abnormal phenotypes. hdg11 mutants show excess branching of the trichome. This phenotype is enhanced in hdg11 hdg12 double mutants. Double mutants were constructed for other paralogous gene pairs and genes within the same subfamily. However, novel phenotypes were observed only for hdg3 atml1 and hdg3 pdf2 mutants that both exhibited defects in cotyledon development. These observations suggest that some of the class IV homeodomain-Leucine zipper members act redundantly with other members of the family during various aspects of cell differentiation. DNA-binding sites were determined for two of the family members using polymerase chain reaction-assisted DNA selection from random oligonucleotides with their recombinant proteins. The binding sites were found to be similar to those previously identified for ATML1 and PDF2, which correspond to the pseudopalindromic sequence 5'-GCATTAAATGC-3' as the preferential binding site.

DOI： 10.1104/pp.106.077388

AtVAM3 is required for normal specification of idioblasts, myrosin cells 査読

H Ueda, C Nishiyama, T Shimada, Y Koumoto, Y Hayashi, M Kondo, T Takahashi, Ohtomo, I, M Nishimura, Hara-Nishimura, I

PLANT AND CELL PHYSIOLOGY 47 ( 1 ) 164 - 175 2006年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

Myrosin cells in Capparales plants are idioblasts that accumulate thioglucoside glucohydrolase (TGG, also called myrosinase), which hydrolyzes glucosinolates to produce toxic compounds for repelling pests. Here, we show that AtVAM3 is involved in development of myrosin cells. It has been shown that yeast VAM3 is a Q.-SNARE that is involved in vesicle transport of vacuolar proteins and vacuolar assembly. We found that two Arabidopsis atvam3 alleles, atvam3-3 and atvain3-4/ssin, accumulate large amounts of TGG1 and TGG2 that are enzymatically active. An immunogold analysis revealed that TGGs were specifically localized in the vacuole of myrosin cells in atvam3 mutants. This result indicates that TGGs are normally transported to vacuoles in these mutants and that AtVAM3 is not essential for vacuolar transport of the proteins. We developed a staining method with Coomassie brilliant blue that detects myrosin cells in whole leaves by their high TGG content. This method showed that atvam3 leaves have a larger number of myrosin cells than do wild-type leaves. Myrosin cells were scattered along leaf veins in wild-type leaves, while they were abnormally distributed in atvam3 leaves. The mutants developed a network of myrosin cells throughout the leaves: myrosin cells were not only distributed continuously along leaf veins, but were also observe independent of leaf veins. The excess of myrosin cells in atvam3 mutants might be responsible for the abnormal abundance of TGGs and the reduction of elongation of inflorescence stems and leaves in these mutants. Our results suggest that AtVAM3 has a plant-specific function in development of myrosin cells.

DOI： 10.1093/pcp/pci232

Identification of an allele of VAM3/SYP22 that confers a semi-dwarf phenotype in Arabidopsis thaliana 査読

Ohtomo, I, H Ueda, T Shimada, C Nishiyama, Y Komoto, Hara-Nishimura, I, T Takahashi

PLANT AND CELL PHYSIOLOGY 46 ( 8 ) 1358 - 1365 2005年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

The short stem and midrib (ssm) mutants of Arabidopsis thaliana show both semi-dwarf and wavy leaf phenotypes due to defects in the elongation of the stem internodes and leaves. Moreover, these abnormalities cannot be recovered by exogenous phytohormones. ssm was originally identified as a single recessive mutant of the ecotype Columbia (Col-0), but genetic crossing experiments have revealed that this mutant phenotype is restored by another gene that is functional in the ecotype Landsberg erecta (Ler) and not in Col-0. Map-based cloning of the gene that is defective in ssm mutants has uncovered a small deletion in the sixth intron of a gene encoding a syntaxin, VAM3/SYP22, which has been implicated in vesicle transport to the vacuole. This mutation appears to cause a peptide insertion in the deduced VAM3/SYP22 polypeptide sequence due to defective splicing of the shortened sixth intron. Significantly, when compared with the wild-type Ler genome, the wild-type Col-0 genome has a single base pair deletion causing a frameshift mutation in SYP23, a gene with the highest known homology to VAM3/SYP22. These findings suggest that VAM3/SYP22 and SYP23 have overlapping functions and that the vesicle transport mediated by these syntaxins is important for shoot morphogenesis.

DOI： 10.1093/pcp/pci146

AtXTH27 plays an essential role in cell wall modification during the development of tracheary elements

A Matsui, R Yokoyama, M Seki, T Ito, K Shinozaki, T Takahashi, Y Komeda, K Nishitani

PLANT JOURNAL 42 ( 4 ) 525 - 534 2005年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

Xyloglucan endotransglucosylases/hydrolases (XTHs) are a class of enzymes capable of catalyzing the molecular grafting between xyloglucans and/or the endotype hydrolysis of a xyloglucan molecule. They are encoded by 33 genes in Arabidopsis. Whereas recent studies have revealed temporally and spatially specific expression profiles for individual members of this family in plants, their biological roles are still to be clarified. To identify the role of each member of this gene family, we examined phenotypes of mutants in which each of the Arabidopsis XTH genes was disrupted. This was undertaken using a reverse genetic approach, and disclosed two loss-of-function mutants for the AtXTH27 gene, xth27-1 and xth27-2. These exhibited short-shaped tracheary elements in tertiary veins, and reduced the number of tertiary veins in the first leaf. In mature rosette leaves of the mutant, yellow lesion-mimic spots were also observed. Upon genetic complementation by introducing the wild-type XTH27 gene into xth27-1 mutant plants, the number of tertiary veins was restored, and the lesions disappeared completely. Extensive expression of the pXTH27::GUS fusion gene was observed in immature tracheary elements in the rosette leaves. The highest level of AtXTH27 mRNA expression in the rosette leaves was observed during leaf expansion, when the tracheary elements were elongating. These findings indicate that AtXTH27 plays an essential role during the generation of tracheary elements in the rosette leaves of Arabidopsis.

DOI： 10.1111/j.1365-313X.2005.02395.x

The plant exon finder: a tool for precise detection of exons using a T-DNA-based tagging approach

F Jingu, T Shirase, Ohtomo, I, A Imai, Y Komeda, T Takahashi

GENE 338 ( 2 ) 267 - 273 2004年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

We have developed a new tool, named the plant exon finder (PEF), for identifying exons in plant genome sequences as an applied technique of T-DNA insertional mutagenesis. The T-DNA constructs contain a heat-shock gene promoter or the cauliflower mosaic virus (CaMV) 35S promoter, followed by the first exon of an Arabidopsis gene with its start codon and the intron donor sequence facing the TDNA left border (LB) in order to trap exons in the genome. The constructs were used to make transgenic Arabidopsis plants. We generated 280 transgenic lines and identified 156 T-DNA-tagged readthrough transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) using an oligo(dT)-linker primer and a T-DNA-specific primer. Sequence analysis of the RT-PCR products revealed that 18 of them carried cDNAs processed by the use of an intron acceptor sequence adjacent to T-DNA insertion sites and 11 of them were in-frame fusions. In one case, the readthrough transcript trapped an exon located 1.6 kb downstream of the site of the insertion. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.gene.2004.06.004

Gene silencing using a heat-inducible RNAi system in Arabidopsis

F Masclaux, M Charpenteau, T Takahashi, R Pont-Lezica, JP Galaud

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 321 ( 2 ) 364 - 369 2004年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

Controlling gene expression during plant development is an efficient tool to explore gene function. In this paper, we describe a gene expression system driven by a heat-shock gene promoter (HSP18.2), to trigger the expression of an intron-containing inverted-repeat. RNA interference became a powerful way for gene functional analysis by reverse genetic approaches. However, constitutive gene silencing cannot be used with genes involved in fundamental processes such as embryo viability. Inducible promoters provide an alternative approach for temporal and spatial gene expression control and we described here a new system, complementary to those using chemical gene inducers. To evaluate the efficiency of this system, RNA corresponding to the phytoene desaturase gene of Arabidopsis thaliana was used as a reporter gene in transgenic plants and a comparative study was performed using either the CaMV35S constitutive promoter or the HSP18.2 inducible promoter. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2004.06.154

Spermidine synthase genes are essential for survival of Arabidopsis

A Imai, T Matsuyama, Y Hanzawa, T Akiyama, M Tamaoki, H Saji, Y Shirano, T Kato, H Hayashi, D Shibata, S Tabata, Y Komeda, T Takahashi

PLANT PHYSIOLOGY 135 ( 3 ) 1565 - 1573 2004年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC PLANT BIOLOGISTS

The cellular polyamines putrescine, spermidine, and spermine are ubiquitous in nature and have been implicated in a wide range of growth and developmental processes. There is little information, however, on mutant plants or animals defective in the synthesis of polyamines. The Arabidopsis genome has two genes encoding spermidine synthase, SPDS1 and SPDS2. In this paper, we describe T-DNA insertion mutants of both of these genes. While each mutant allele shows normal growth, spds1-1 spds2-1 double-mutant seeds are abnormally shrunken and they have embryos that are arrested morphologically at the heart-torpedo transition stage. These seeds contain significantly reduced levels of spermidine and high levels of its precursor, putrescine. The embryo lethal phenotype of spds1-1 spds2-1 is complemented by the wild-type SPDS1 gene. In addition, we observed a nearly identical seed phenotype among an F, seed population from the cross between the spds2-1. allele and SPDS1 RNA interference transgenic lines. These data provide the first genetic evidence indicating a critical role of the spermidine synthase in plant embryo development.

DOI： 10.1104/pp.104.041699

Spermine is not essential for survival of Arabidopsis

A Imai, T Akiyama, T Kato, S Sato, S Tabata, KT Yamamoto, T Takahashi

FEBS LETTERS 556 ( 1-3 ) 148 - 152 2004年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Spermine is the final product of the polyamine biosynthetic pathway and is ubiquitously present in most organisms. The genome of Arabidopsis thaliana has two genes encoding spermine synthase: ACAULIS5 (ACL5), whose loss-of-function mutants show a severe defect in stem elongation, and SPMS. In order to elucidate the function of spermine in plants, we isolated a T-DNA insertion mutant of the SPMS gene. Free and conjugated spermine levels in the mutant, designated spms-1, were significantly decreased compared with those in the wildtype, but no obvious morphological phenotype was observed in spms-1 plants. We further confirmed that acl5-1 spms-1 double mutants contained no spermine. Surprisingly, acl5-1 spms-1 was fully as viable as the wild-type and showed no phenotype except for the reduced stem growth due to acl5-1. These results indicate that spermine is not essential for survival of Arabidopsis, at least under normal growth conditions. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/S0014-5793(03)01395-4

Regulation of shoot epidermal cell differentiation by a pair of homeodomain proteins in Arabidopsis

M Abe, H Katsumata, Y Komeda, T Takahashi

DEVELOPMENT 130 ( 4 ) 635 - 643 2003年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：COMPANY OF BIOLOGISTS LTD

In higher plants, the outermost cell layer (L1) of the shoot apex gives rise to the epidermis of shoot organs. Our previous study demonstrated that an 8-bp motif named the L1 box functions as a cis-regulatory element for L1-specific gene expression in the shoot system of Arabidopsis. We show here that PROTODERMAL FACTOR2 (PDF2), a member of the HD-GL2 class of homeobox genes, is expressed exclusively in the L1 of shoot meristems and that recombinant PDF2 protein specifically binds to the L1 box in vitro. Although knockout mutants of PDF2 and ATML1, another L1-specific HD-GL2 class gene sharing the highest homology with PDF2, display normal shoot development, the double mutant results in severe defects in shoot epidermal cell differentiation. This suggests that PDF2 and ATML1 are functionally interchangeable and play a critical role in maintaining the identity of L1 cells, possibly by interacting with their L1 box and those of downstream target-gene promoters.

DOI： 10.1242/dev.00292

Characterization of the spermidine synthase-related gene family in Arabidopsis thaliana

Y Hanzawa, A Imai, AJ Michael, Y Komeda, T Takahashi

FEBS LETTERS 527 ( 1-3 ) 176 - 180 2002年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

The Arabidopsis genome contains four genes that encode proteins similar to both spermidine synthase and spermine synthase of other organisms. Our previous study revealed that one of these genes, designated ACAULIS5 (ACL5), encodes spermine synthase and that its null mutation results in a severe defect in the elongation of stem internodes. Here we report the characterization of the other three genes, designated SPDS1, SPDS2 and SPDS3. Our results showed that SPDS1 and SPDS2 possess spermidine synthase activity in yeast spermidine synthase-deficient mutants, but the enzyme activity of SPDS3 remained to be determined. RNA gel blot analysis revealed that all of these genes are expressed in all plant organs but show different responses to exogenous plant hormones, suggesting that they are involved in different aspects of growth by modulating the contents of polyamines in plant cells. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0014-5793(02)03217-9

Disruption of a DNA topoisomerase I gene affects morphogenesis in Arabidopsis

T Takahashi, S Matsuhara, M Abe, Y Komeda

PLANT CELL 14 ( 9 ) 2085 - 2093 2002年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC PLANT BIOLOGISTS

The genesis of phyllotaxis, which often is associated with the Fibonacci series of numbers, is an old unsolved puzzle in plant morphogenesis. Here, we show that disruption of an Arabidopsis topoisomerase (topo) I gene named TOP1alpha affects phyllotaxis and plant architecture. The divergence angles and internode lengths between two successive flowers were more random in the top1alpha mutant than in the wild type. The top1alpha plants sporadically produced multiple flowers from one node, and the number of floral organ primordia often was different. The mutation also caused the twisting of inflorescences; and individual flowers and the serration of leaf margins. These morphological abnormalities indicate that TOP1alpha may play a critical role in the maintenance of a regular pattern of organ initiation. The top1alpha mutant transformed with the RNA interference construct for TOP1beta, another topo I gene arrayed tandemly with TOP1alpha, was found to be lethal at young seedling stages, suggesting that topo I activity is essential in plants.

DOI： 10.1105/tpc.001925

Formation of corymb-like inflorescences due to delay in bolting and flower development in the corymbosa2 mutant of arabidopsis

M Suzuki, T Takahashi, Y Komeda

PLANT AND CELL PHYSIOLOGY 43 ( 3 ) 298 - 306 2002年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

Among the wild-type ecotypes of Arabidopsis thaliana vegetative shoot meristem to an inflorescence meristem is whose shape of inflorescence is categorized as raceme, the ecotype Landsberg harboring the erecta (er) mutation shows a corymb-like inflorescence, namely, a compact inflorescence with a flattened arrangement of flower buds at the tip. The fact that the ER gene encodes a receptor-like protein kinase implies the presence of a signaling cascade responsible for the inflorescence morphology of flowering plants. We report here the characterization of another mutant with a corymb-like inflorescence, named corymbosa2 (crm2), and the isolation of the CRM2 gene. While the er mutation causes a severe reduction in the length of pedicels, the crm2 mutation results in a significant delay in the initiation of internode elongation and in the development of flowers, despite having little effect on the timing of floral induction. Consequently, the number of flower buds is apparently increased at the tip of crm2 inflorescence. The crm2 er double mutant shows an additive phenotype. These results suggest that CRM2 and ER may act in different ways to generate wild-type inflorescence. The CRM2 gene was isolated by positional cloning and appears to encode a polypeptide with no significant homology to known sequences.

DOI： 10.1093/pcp/pcf036

Identification of a cis-regulatory element for L1 layer-specific gene expression, which is targeted by an L1-specific homeodomain protein

M Abe, T Takahashi, Y Komeda

PLANT JOURNAL 26 ( 5 ) 487 - 494 2001年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BLACKWELL SCIENCE LTD

The Arabidopsis thaliana PROTODERMAL FACTOR1 (PDF1) gene encoding a putative extracellular proline-rich protein is exclusively expressed in the L1 layer of shoot apices and the protoderm of organ primordia. In order to identify essential cis-regulatory sequences required for the L1 layer-specific expression, a series of 5' deletions of the PDF1 promoter were fused to the beta -glucronidase (GUS) gene and introduced into Arabidopsis plants. Our analysis revealed that the minimum region necessary to confer L1-specific expression of PDF1 is confined within a 260-bp fragment upstream of the transcription start site. We identified an 8-bp motif in this region that is conserved between promoter regions of all the L1-specific genes so far cloned, and we designated it the L1 box. Electrophoretic mobility shift assays demonstrated that the L1-specific homeodomain protein ATML1 can bind to the L1 box sequence in vitro. The GUS expression in transgenic plants disappeared when a mutation that abolishes binding of ATML1 was introduced into the PDF1 /1 box sequence of the construct. These results suggest that the L1 box plays a crucial role in the regulation of PDF1 expression in L1 cells and that ATML1 could cooperate to drive L1-specific expression.

DOI： 10.1046/j.1365-313X.2001.01047.x

ACAULIS5, an Arabidopsis gene required for stem elongation, encodes a spermine synthase

Y Hanzawa, T Takahashi, AJ Michael, D Burtin, D Long, M Pineiro, G Coupland, Y Komeda

EMBO JOURNAL 19 ( 16 ) 4248 - 4256 2000年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

Polyamines have been implicated in a wide range of biological processes, including growth and development in bacteria and animals, but their function in higher plants is unclear. Here we show that the Arabidopsis ACAULIS5 (ACL5) gene, whose inactivation causes a defect in the elongation of stem internodes by reducing cell expansion, encodes a protein that shares sequence similarity with the polyamine biosynthetic enzymes spermidine synthase and spermine synthase, Expression of the recombinant ACL5 protein in Escherichia coli showed that ACL5 possesses spermine synthase activity. Restoration of the acl5 mutant phenotype by somatic reversion of a transposon-induced allele suggests a non-cell-autonomous function for the ACL5 gene product, We also found that expression of the ACL5 cDNA under the control of a heat shock gene promoter in acl5 mutant plants restores the phenotype in a heat shock-dependent manner. The results of the experiments showed that polyamines play an essential role in promotion of internode elongation through cell expansion in Arabidopsis, We discuss the relationships to plant growth regulators such as auxin and gibberellins that have related functions.

DOI： 10.1093/emboj/19.16.4248

Heat-shock tagging: a simple method for expression and isolation of plant genome DNA flanked by T-DNA insertions

S Matsuhara, F Jingu, T Takahashi, Y Komeda

PLANT JOURNAL 22 ( 1 ) 79 - 86 2000年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BLACKWELL SCIENCE LTD

This paper describes expression profiles of the Arabidopsis HSP18.2 heat-shock gene promoter by using three different reporter genes, and the application of this promoter to a method we have developed to drive heat-shock-dependent transcription of plant genome DNA flanked by T DNA insertions. We show that, irrespective of the location of the T-DNA insertion, an HSP18.2 promoter towards the left border of the T-DNA effectively induces transcription of flanking genome sequences in response to heat shock, if polyadenylated, tagged transcripts can be easily identified by RT-PCR.

DOI： 10.1046/j.1365-313X.2000.00716.x

Salicylic acid induces the expression of a number of receptor-like kinase genes in Arabidopsis thaliana

Y. Ohtake, T. Takahashi, Y. Komeda

Plant and Cell Physiology 41 ( 9 ) 1038 - 1044 2000年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Society of Plant Physiologists

Receptor-like protein kinases (RLKs) are encoded by a divergent multigene family and their functions have been implicated in a wide range of signal transduction pathways. In this study, we examined the effect of salicylic acid (SA) on the expression of RLK genes in Arabidopsis thaliana. RNA gel blot analysis revealed that transcripts of RKC1 and a number of its homologs, whose translation products contain C-X8-C-X2-C motifs in the putative extracellular domain, accumulated to a higher level in response to SA treatment of plants. The chimeric fusion between the RKC1 5'-upstream region and the β-glucuronidase (GUS) reporter gene reproduced the SA responsiveness in transgenic plants. In addition, some of RLK genes of the leucine-rich repeat (LRR) class and those of the S-domain class were also induced by SA. We found that the upstream regions of these SA-responsive RLK genes contain the TTGAC sequence, which has been suggested to be important for induced expression of many plant defense genes. These results suggest the involvement of a number of RLKs in SA-mediated defense responses.

DOI： 10.1093/pcp/pcd028

茎伸長の分子機構

半澤芳恵, 高橋卓, 米田好文

細胞工学別冊植物細胞工学シリーズ 12巻 128-137頁 2000年

Expression of endoxyloglucan transferase genes in acaulis mutants of Arabidopsis

T Akamatsu, Y Hanzawa, Y Ohtake, T Takahashi, K Nishitani, Y Komeda

PLANT PHYSIOLOGY 121 ( 3 ) 715 - 721 1999年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC PLANT PHYSIOLOGISTS

A mutant of Arabidopsis with reduced internodal cell length, acaulis5 (acl5), has recently been shown to have reduced transcript levels of a gene for endoxyloglucan transferase, EXGT-A1 (Y. Hanzawa, T. Takahashi, Y. Komeda [1997] Plant J 12: 863-874). In the present study, we cloned genomic fragments of five members of the EXGT gene family, EXGT-A1, EXGT-A3, EXGT-A4, XTR2, and XTR3, and examined their expression in the wild type and in a series of acl mutants. In wild-type plants, the EXGT-A3 gene showed higher expression in lower internodes (internodes between nodes bearing axillary shoots) than in upper and young internodes, in which EXGT-A1 was highly expressed. EXGT-A4 was preferentially expressed in roots and XTR3 in siliques. The XTR2 gene was constitutively expressed. In acl1, acl3, and acl4 mutants, which have a severe defect in leaf expansion as well as in internode elongation, the EXGT-A1 gene showed reduced levels of expression before bolting of plants. In contrast, XTR3 was increased in these mutant seedlings. Reduction of EXGT-A1 expression was also detected after bolting of all acl mutants except acl2, whose growth defect is restricted to lower internodes. These results suggest the involvement of each EXGT in different aspects of organ development.

DOI： 10.1104/pp.121.3.715

Cloning and characterization of an L1 layer-specific gene in Arabidopsis thaliana

M Abe, T Takahashi, Y Komeda

PLANT AND CELL PHYSIOLOGY 40 ( 6 ) 571 - 580 1999年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC PLANT PHYSIOLOGISTS

The shoot apical meristem unknown. In order to identify the genes that function in the SAM, we performed cDNA subtraction experiments between wild-type and terminal flower1 shoot apices. Here, we describe the cloning of a gene designated PDF1 (PROTODERMAL FACTOR1). In situ hybridization revealed that the expression of PDF1 is exclusively limited to the L1 layer of vegetative, inflorescence and floral meristems and to the protoderm of organ primordia. By contrast, P (SAM) of Arabidopsis thaliana constitutes the tunica of L1 and L2 and the corpus represented by L3 cells. Regulatory networks involved in establishing and maintaining this structure of shoot meristems remain largelyDF1 shows no detectable level of expression in the epidermis of mature organs. Specific expression of the PDF1 gene in protodermal cells is also observed during embryogenesis. The deduced amino acid sequence of PDF1 shares no significant homology with that of other known proteins but contains a putative signal peptide and novel proline-rich repeat motifs, suggesting a cell-wall protein. Possible roles of the PDF1 gene in the SAM are discussed.

熱ショック応答の分子機構

高橋卓, 米田好文

蛋白質核酸酵素臨時増刊「環境応答・適応の分子機構」 44巻 39-44頁 1999年

The Arabidopsis ERECTA gene is expressed in the shoot apical meristem and organ primordia(共著)

Plant Journal 15 ( 3 ) 301 - 310 1998年8月

Identification by PCR of receptor-like protein kinases from Arabidopsis flowers. (共著)

Plant Molecular Biology 37 ( 4 ) 587 - 596 1998年7月

ACL5 : an Arabidopsis gene required for internodal elongation after flowering(共著)

Plant Journal 12 ( 4 ) 863 - 874 1997年

DIMINUTO gene of Arabidopsis is involved in regulating cell elongation(共著)

Takahashi T

Gene & Development 9 ( 1 ) 97 - 107 1995年1月

ANALYSIS OF TISSUE-SPECIFIC EXPRESSION OF ARABIDOPSIS-THALIANA HSP9O-FAMILY GENE HSP81 査読

N YABE, T TAKAHASHI, Y KOMEDA

PLANT AND CELL PHYSIOLOGY 35 ( 8 ) 1207 - 1219 1994年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC PLANT PHYSIOLOGISTS

We have isolated three HSP90-family genes from Arabidopsis: HSP81-1 which is heat-inducible, and HSP81-2 and -3 which are highly expressed under normal growth temperatures. Northern blot analysis and RNase protection analysis, using gene specific probes, showed that HSP81-2 and -3 mRNA were present in all tissues and abundant in roots, floral bud clusters, and flowers at 22 degrees C. A small amount of HSP81-1 mRNA was detected only in roots. In situ hybridization and histochemical analysis using transgenic plants carrying chimeric gene fusions, with an HSP81 promotor region fused to a beta-glucuronidase (GUS) gene, confirmed these results. At 22 degrees C, high GUS activity was observed in the root apical meristems, pollen and tapeta in HSP81-2::GUS and HSP81-3::GUS transgenic plants, while only branches of the root in HSP81-1::GUS transgenic plants expressed high GUS activity. After 2 hours of 35 degrees C treatment, extensively high GUS activity was observed in all tissues in HSP81-1::GUS transgenic plants, while elevated but tissue specific expression was observed in HSP81-2 and -3 transgenic plants.
Exogenous application of various chemicals such as ABA, GA(3), kinetin, IAA, NaCl, and mannitol revealed that 10 mM IAA and 0.1 M NaCl significantly enhanced the accumulation of HSP81-2 and -3 transcripts. Only a slight response to IAA was observed in HSP81-1 mRNA accumulation at 22 degrees C; the increase was possibly caused by a novel pathway other than heat-shock-response pathway.

Expression in yeast of a fusion gene composed of the promoter of a heat-shock gene from Arabidopsis and a bacterial gene for β-glucuronidase(共著)

TAKAHASHI Taku, YABE Naoto, KOMEDA Yoshibumi

Plant and Cell Physiology 34 ( 1 ) 161 - 164 1993年

記述言語：英語出版者・発行元：Japanese Society of Plant Physiologists

Production of a functional β-glucuronidase (GUS) protein was induced by exposure of exponentially growing yeast cells to heat shock after transformation of the GUS gene under the control of the promoter of the heat-shock gene, HSP18.2, from Arabidopsis. Yeast cyr and bcy mutations appeared to have essentially no effect.

その他リンク： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=181806

The Arabidopsis HPS18.2 promoter/GUS gene fusion in transgenic Arabidopsis plants : a powerful tool for the isolation of regulatory mutants of the heat-shock response(共著)

Plant Journal 2 ( 5 ) 751 - 761 1992年

Isolation and analysis of the expression of two genes for the 81-kilodalton heat-shock proteins from Arabidopsis(共著)

Plant Physiology 99 ( 2 ) 383 - 390 1992年

Heat-shock induced accumulation of extremely long transcripts containing the rDNA intergenic spacer in Arabidopsis(共著)

Takahashi Taku, Komeda Yoshibumi

Plant and Cell Physiology 33 ( 4 ) 389 - 394 1992年

記述言語：英語出版者・発行元：Japanese Society of Plant Physiologists

A cDNA clone containing a 1.2-kb fragment derived from the ribosomal DNA (rDNA) intergenic spacer (IGS) of Arabidopsis was characterized. Isolation of this clone was achieved in a previous study by differential screening of a cDNA library prepared from heat-shocked Arabidopsis seedlings (Takahashi and Komeda 1989). Nucleotide sequence analysis revealed that the cDNA had an oligo(dA) sequence that corresponded to the sequence found in the IGS. Northern blot analysis using the cloned cDNA as probe demonstrated that heat-shock treatment of seedlings induced the accumulation of extremely long transcripts with apparent lengths of more than 7 kb. Treatment with arsenite and cadmium ions also led to the accumulation of the RNA, a phenomenon very similar to that observed in the case of expression of genes for heat-shock proteins (HSPs). Although the possibility remains to be excluded that these transcripts might be derived from,a region homologous to the IGS Iocated outside the rDNA clusters in Arabidopsis, it is most likely that processing of precursor rRNA and/or termination of transcription of rRNA are greatly impaired under stressed conditions in plants, as reported in the case of animal genes for rRNA (Labhart and Reeder 1987, Parker and Bond 1989).

その他リンク： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=181630

Characterization of two genes encoding small heat-shock proteins in Arabidopsis thaliana(共著)

Takahashi T, Komeda Y

Molecular and General Genetics 219 ( 3 ) 365 - 372 1989年11月

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