研究者詳細 - 馬　建鋒

論文 - 馬　建鋒

分割表示 344 件中 121 - 140 件目／全件表示 >>

Identification of a mammalian silicon transporter

Sarah Ratcliffe, Ravin Jugdaohsingh, Julien Vivancos, Alan Marron, Rupesh Deshmukh, Jian Feng Ma, Namiki Mitani-Ueno, Jack Robertson, John Wills, Mark V. Boekschoten, Michael Mueller, Robert C. Mawhinney, Stephen D. Kinrade, Paul Isenring, Richard R. Belanger, Jonathan J. Powell

AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY 312 ( 5 ) C550 - C561 2017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：AMER PHYSIOLOGICAL SOC

Silicon (Si) has long been known to play a major physiological and structural role in certain organisms, including diatoms, sponges, and many higher plants, leading to the recent identification of multiple proteins responsible for Si transport in a range of algal and plant species. In mammals, despite several convincing studies suggesting that silicon is an important factor in bone development and connective tissue health, there is a critical lack of understanding about the biochemical pathways that enable Si homeostasis. Here we report the identification of a mammalian efflux Si transporter, namely Slc34a2 (also termed NaPiIIb), a known sodium-phosphate cotransporter, which was upregulated in rat kidney following chronic dietary Si deprivation. Normal rat renal epithelium demonstrated punctate expression of Slc34a2, and when the protein was heterologously expressed in Xenopus laevis oocytes, Si efflux activity (i.e., movement of Si out of cells) was induced and was quantitatively similar to that induced by the known plant Si transporter OsLsi2 in the same expression system. Interestingly, Si efflux appeared saturable over time, but it did not vary as a function of extracellular HPO42- or Na+ concentration, suggesting that Slc34a2 harbors a functionally independent transport site for Si operating in the reverse direction to the site for phosphate. Indeed, in rats with dietary Si depletion-induced upregulation of transporter expression, there was increased urinary phosphate excretion. This is the first evidence of an active Si transport protein in mammals and points towards an important role for Si in vertebrates and explains interactions between dietary phosphate and silicon.

DOI： 10.1152/ajpcell.00219.2015

Polar Localization of the NIP5;1 Boric Acid Channel Is Maintained by Endocytosis and Facilitates Boron Transport in Arabidopsis Roots

Sheliang Wang, Akira Yoshinari, Tomoo Shimada, Ikuko Hara-Nishimura, Namiki Mitani-Ueno, Jian Feng Ma, Satoshi Naito, Junpei Takano

PLANT CELL 29 ( 4 ) 824 - 842 2017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：AMER SOC PLANT BIOLOGISTS

Boron uptake in Arabidopsis thaliana is mediated by nodulin 26-like intrinsic protein 5;1 (NIP5;1), a boric acid channel that is located preferentially on the soil side of the plasma membrane in root cells. However, the mechanism underlying this polar localization is poorly understood. Here, we show that the polar localization of NIP5;1 in epidermal and endodermal root cells is mediated by the phosphorylation of Thr residues in the conserved TPG (ThrProGly) repeat in the N-terminal region of NIP5;1. Although substitutions of Ala for three Thr residues in the TPG repeat did not affect lateral diffusion in the plasma membrane, these substitutions inhibited endocytosis and strongly compromised the polar localization of GFP-NIP5;1. Consistent with this, the polar localization was compromised in m subunit mutants of the clathrin adaptor AP2. The Thr-to-Ala substitutions did not affect the boron transport activity of GFP-NIP5;1 in Xenopus laevis oocytes but did inhibit the ability to complement boron translocation to shoots and rescue growth defects in nip5;1-1 mutant plants under boron-limited conditions. These results demonstrate that the polar localization of NIP5;1 is maintained by clathrin-mediated endocytosis, is dependent on phosphorylation in the TPG repeat, and is necessary for the efficient transport of boron in roots.

DOI： 10.1105/tpc.16.00825

The Key to Vn Homeostasis in Plants: Regulation of Mn Transporters

Ji Feng Shao, Naoki Yamaji, Ren Fang Shen, Jian Feng Ma

TRENDS IN PLANT SCIENCE 22 ( 3 ) 215 - 224 2017年3月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE LONDON

Plants only require small amounts of manganese (Mn) for healthy growth, but Mn concentrations in soil solution vary from sub-micromolar to hundreds of micromolar across the growth period. Therefore, plants must deal with large Mn concentration fluctuations, but the molecular mechanisms underlying how plants cope with low and high Mn concentrations are poorly understood. In this Opinion we discuss the role of Mn transporters in the uptake, distribution, and detoxification of Mn in response to changes in Mn concentrations through their regulation at the transcriptional and protein levels, mainly focusing on rice, an Mn-tolerant and accumulating species. We also propose mechanisms involved in the hyperaccumulation of Mn and future prospects for studying this specific trait.

DOI： 10.1016/j.tplants.2016.12.005

Reducing phosphorus accumulation in rice grains with an impaired transporter in the node (vol 541, pg 92, 2017) 査読

Naoki Yamaji, Yuma Takemoto, Takaaki Miyaji, Namiki Mitani-Ueno, Kaoru T. Yoshida, Jian Feng Ma

NATURE 541 ( 7635 ) 136 - 136 2017年1月

Iron-induced nitric oxide leads to an increase in the expression of ferritin during the senescence of Lotus japonicus nodules

Sirinapa Chungopast, Mallika Duangkhet, Shigeyuki Tajima, Jian Feng Ma, Mika Nomura

JOURNAL OF PLANT PHYSIOLOGY 208 40 - 46 2017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 GMBH, URBAN & FISCHER VERLAG

Iron is an essential nutrient for legume-rhizobium symbiosis and accumulates abundantly in the nodules. However, the concentration of free iron in the cells is strictly controlled to avoid toxicity. It is known that ferritin accumulates in the cells as an iron storage protein. During nodule senescence, the expression of the ferritin gene, Ljfer1, was induced in Lotus japonicus. We investigated a signal transduction pathway leading to the increase of Ljfer1 in the nodule. The Ljfer1 promoter of L. japonicus contains a conserved Iron-Dependent Regulatory Sequence (IDRS). The expression of Ljfer1 was induced by the application of iron or sodium nitroprusside, which is a nitric oxide (NO) donor. The application of iron to the nodule increased the level of NO. These data strongly suggest that iron-induced NO leads to increased expression of Ljfer1 during the senescence of L. japonicus nodules. (C) 2016 Elsevier GmbH. All rights reserved.

DOI： 10.1016/j.jplph.2016.11.004

Isolation and characterization of a rice line with high Cd accumulation for potential use in phytoremediation

Ji Feng Shao, Miho Fujii-Kashino, Naoki Yamaji, Shinichi Fukuoka, Ren Fang Shen, Jian Feng Ma

PLANT AND SOIL 410 ( 1-2 ) 357 - 368 2017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：SPRINGER

To reduce cadmium (Cd) intake, remediation of Cd-contaminated soil and breeding crops with low Cd accumulation are important. This study aims to isolate rice mutants with altered accumulation of Cd.We used rice seeds mutated by N-methyl-N-nitrosourea for screening. The mutant was physiologically, genetically, and molecularly characterized. Cd accumulation was compared among five rice varieties cultivated in a Cd-contaminated soil.From 1000 lines screened, we isolated a line (TCM213) with high Cd accumulation. There was no difference in the root Cd uptake, but a higher root-to-shoot translocation of Cd was found in TCM213 compared with a common rice cultivar, T-65. The expression and sequence of OsNramp5 and OsHMA2 did not differ between TCM213 and T-65. However, several SNPs and deletion were found in the sequence of OsHMA3, although its expression and tissue localization were similar to those of T-65. Genetic analysis of an F-2 population derived from T-65 and TCM213 showed that the variation of OsHMA3 explained 72 % of variation in total Cd accumulation. TCM213 accumulated the largest Cd amount in the shoots among five Cd-accumulating varieties.High Cd accumulation in TCM213 results from loss of function of OsHMA3, and its high Cd accumulation has potential for efficient phytoremediation of Cd-contaminated soil.

DOI： 10.1007/s11104-016-3014-y

A model of silicon dynamics in rice 査読

Gen Sakurai, Naoki Yamaji, Namiki Mitani-Ueno, Masayuki Yokozawa, Keisuke Ono, Jian Feng Ma

Frontiers in Plant Science 8 E31-E34 2017年

High Silicon Accumulation in the Shoot is Required for Down-Regulating the Expression of Si Transporter Genes in Rice

Namiki Mitani-Ueno, Naoki Yamaji, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 57 ( 12 ) 2510 - 2518 2016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：OXFORD UNIV PRESS

Rice requires high silicon (Si) for its high and sustainable yield. The efficient uptake of Si in rice is mediated by two transporters OsLsi1 and OsLsi2, which function as influx and efflux transporters, respectively. Our previous studies showed that the mRNA expression levels of these transporter genes were down-regulated by Si. Herein we investigated the mechanism underlying regulation of OsLsi1 and OsLsi2 expression. There was a negative correlation between the expression level of OsLsi1 and OsLsi2 and shoot Si accumulation when the rice seedlings were exposed to different Si supply conditions. A split root experiment showed that the expression of both OsLsi1 and OsLsi2 was also downregulated in half the roots without direct Si exposure when the other half of the roots were exposed to Si. Analysis with transgenic rice carrying different lengths of OsLsi1 promoter regions fused with green fluorescent protein (GFP) as a reporter gene revealed that the region responsible for the Si response of OsLsi1 expression is present between -327 to -292 in the promoter. However, this region was not associated with the tissue and cellular localization of OsLsi1. In conclusion, the Si-induced down-regulation of Si transporter genes is controlled by shoot Si, not root Si, and the region between -327 and -292 in the OsLsi1 promoter is involved in this regulation of OsLsi1 expression in rice.

DOI： 10.1093/pcp/pcw163

Retrotransposon-Mediated Aluminum Tolerance through Enhanced Expression of the Citrate Transporter OsFRDL4

Kengo Yokosho, Naoki Yamaji, Miho Fujii-Kashino, Jian Feng Ma

PLANT PHYSIOLOGY 172 ( 4 ) 2327 - 2336 2016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：AMER SOC PLANT BIOLOGISTS

High aluminum (Al) tolerance of rice (Oryza sativa) is controlled by multiple tolerance genes, but the regulatory mechanisms underlying the differential expression of these genes are poorly understood. Here, we investigated the factors regulating the expression of OsFRDL4, a gene encoding a citrate efflux transporter involved in Al-induced citrate secretion from the roots. Analysis with chromosome segment substitution lines derived from cv Nipponbare (high OsFRDL4 expression) and cv Kasalath (low OsFRDL4 expression) revealed that the differential expression of OsFRDL4 is responsible for the quantitative trait locus for Al tolerance detected previously on chromosome 1. Comparison of the OsFRDL4 gene structure in cv Nipponbare and cv Kasalath showed that there was no difference in the position of the transcriptional start site, but a 1.2-kb insertion showing high similarity to the solo long terminal repeat of the retrotransposon was found in the promoter region of OsFRDL4 in cv Nipponbare. This insertion showed higher promoter activity and contained nine cis-acting elements for ALUMINUM RESISTANCE TRANSCRIPTION FACTOR1 (ART1). However, this insertion did not alter the spatial expression or cellular localization of OsFRDL4. Furthermore, this insertion was found in most japonica varieties but was largely absent from indica varieties or wild rice species. These results indicate that the 1.2-kb insertion in the OsFRDL4 promoter region in japonica subspecies is responsible for their higher expression level of OsFRDL4 due to the increased number of cis-acting elements of ART1. Our results also suggest that this insertion event happened at the initial stage of domestication of japonica subspecies.

DOI： 10.1104/pp.16.01214

The HvNramp5 Transporter Mediates Uptake of Cadmium and Manganese, But Not Iron 国際誌

Dezhi Wu, Naoki Yamaji, Miki Yamane, Miho Kashino-Fujii, Kazuhiro Sato, Jian Feng Ma

PLANT PHYSIOLOGY 172 ( 3 ) 1899 - 1910 2016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 BIOLOGISTS

The Natural Resistance Associated Macrophage Protein (Nramp) represents a transporter family for metal ions in all organisms. Here, we functionally characterized a member of Nramp family in barley (Hordeum vulgare), HvNramp5. This member showed different expression patterns, transport substrate specificity, and cellular localization from its close homolog in rice (Oryza sativa), OsNramp5, although HvNramp5 was also localized to the plasma membrane. HvNramp5 was mainly expressed in the roots and its expression was not affected by Cd and deficiency of Zn, Cu, and Mn, but slightly up-regulated by Fe deficiency. Spatial expression analysis showed that the expression of HvNramp5 was higher in the root tips than that in the basal root regions. Furthermore, analysis with laser microdissection revealed higher expression of HvNramp5 in the outer root cell layers. HvNramp5 showed transport activity for both Mn2+ and Cd2+, but not for Fe2+ when expressed in yeast. Immunostaining with a HvNramp5 antibody showed that this protein was localized in the root epidermal cells without polarity. Knockdown of HvNramp5 in barley resulted in a significant reduction in the seedling growth at low Mn supply, but this reduction was rescued at high Mn supply. The concentration of Mn and Cd, but not other metals including Cu, Zn, and Fe, was decreased in both the roots and shoots of knockdown lines compared with the wild-type barley. These results indicate that HvNramp5 is a transporter required for uptake of Mn and Cd, but not for Fe, and that barley has a distinct uptake system from rice.

DOI： 10.1104/pp.16.01189

OsFRDL1 expressed in nodes is required for distribution of iron to grains in rice

Kengo Yokosho, Naoki Yamaji, Jian Feng Ma

JOURNAL OF EXPERIMENTAL BOTANY 67 ( 18 ) 5485 - 5494 2016年10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

OsFRDL1 expressed in the upper nodes is required for the distribution of Fe to the panicles through solubilizing Fe deposited in the apoplastic part of nodes in rice.Iron (Fe) is essential for plant growth and development, but the molecular mechanisms underlying its distribution to different organs are poorly understood. We found that OsFRDL1 (FERRIC REDUCTASE DEFECTIVE LIKE 1), a plasma membrane-localized transporter for citrate, was highly expressed in the upper nodes of rice at the reproductive growth stage. OsFRDL1 was expressed in most cells of enlarged vascular bundles, diffuse vascular bundles, and the interjacent parenchyma cell bridges of uppermost node I, as well as vascular tissues of the leaf blade, leaf sheath, peduncle, rachis, husk, and stamen. Knockout of OsFRDL1 decreased pollen viability and grain fertility when grown in a paddy field. Iron was deposited in the parenchyma cell bridges, a few of the cell layers of the parenchyma tissues outside of the bundle sheath of enlarged vascular bundles in node I in both the wild-type rice and osfrdl1 mutant, but the mutant accumulated more Fe than the wild-type rice in this area. A stem-fed experiment with stable isotope Fe-57 showed that the distribution of Fe in the anther and panicle decreased in the knockout line, but that in the flag leaf it increased compared with the wild-type rice. Taken together, our results show that OsFRDL1 expressed in the upper nodes is required for the distribution of Fe in the panicles through solubilizing Fe deposited in the apoplastic part of nodes in rice.

DOI： 10.1093/jxb/erw314

A heavy metal P-type ATPase OsHMA4 prevents copper accumulation in rice grain

Xin-Yuan Huang, Fenglin Deng, Naoki Yamaji, Shannon R. M. Pinson, Miho Fujii-Kashino, John Danku, Alex Douglas, Mary Lou Guerinot, David E. Salt, Jian Feng Ma

NATURE COMMUNICATIONS 7 2016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：NATURE PUBLISHING GROUP

Rice is a major source of calories and mineral nutrients for over half the world's human population. However, little is known in rice about the genetic basis of variation in accumulation of copper (Cu), an essential but potentially toxic nutrient. Here we identify OsHMA4 as the likely causal gene of a quantitative trait locus controlling Cu accumulation in rice grain. We provide evidence that OsHMA4 functions to sequester Cu into root vacuoles, limiting Cu accumulation in the grain. The difference in grain Cu accumulation is most likely attributed to a single amino acid substitution that leads to different OsHMA4 transport activity. The allele associated with low grain Cu was found in 67 of the 1,367 rice accessions investigated. Identification of natural allelic variation in OsHMA4 may facilitate the development of rice varieties with grain Cu concentrations tuned to both the concentration of Cu in the soil and dietary needs.

DOI： 10.1038/ncomms12138

Transporters involved in mineral nutrient uptake in rice

Akimasa Sasaki, Naoki Yamaji, Jian Feng Ma

JOURNAL OF EXPERIMENTAL BOTANY 67 ( 12 ) 3645 - 3653 2016年6月

記述言語：英語出版者・発行元：OXFORD UNIV PRESS

One of the most important roles of plant roots is to take up essential mineral nutrients from the soil for use in plant growth and development. The uptake of mineral elements is mediated by various transporters belonging to different transporter families. Here we reviewed transporters for the uptake of macronutrients and micronutrients identified in rice, an important staple food for half of the world's population. Rice roots are characterized by having two Casparian strips on the exodermis and endodermis and by the formation of aerenchyma in the mature root zone. This distinct anatomical structure dictates that a pair of influx and efflux transporters at both the exodermis and endodermis is required for the radial transport of a mineral element from the soil solution to the stele. Some transporters showing polar localization at the distal and proximal sides of the exodermis and endodermis have been identified for silicon and manganese, forming an efficient uptake system. However, transporters for the uptake of most mineral elements remain to be identified.

DOI： 10.1093/jxb/erw060

An Aluminum-Inducible IREG Gene is Required for Internal Detoxification of Aluminum in Buckwheat

Kengo Yokosho, Naoki Yamaji, Namiki Mitani-Ueno, Ren Fang Shen, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 57 ( 6 ) 1169 - 1178 2016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：OXFORD UNIV PRESS

Buckwheat (Fagopyrum esculentum Moench) is able to detoxify aluminum (Al) both externally and internally, but the molecular mechanisms underlying its high Al tolerance are not understood. We functionally characterized a gene (FeIREG1) belonging to IRON REGULATED/ferroportin in buckwheat, which showed high expression in our previous genome-wide transcriptome analysis. FeIREG1 was mainly expressed in the roots, and its expression was up-regulated by Al, but not by other metals and low pH. Furthermore, in contrast to AtIREG1 and AtIREG2 in Arabidopsis, the expression of FeIREG1 was not induced by Fe deficiency. Spatial expression analysis showed that the Al-induced expression of FeIREG1 was found in the root tips and higher expression was detected in the outer layers of this part. Immunostaining also showed that FeIREG1 was localized at the outer cell layers in the root tip. A FeIREG1-green fluorescent protein (GFP) fusion protein was localized to the tonoplast when transiently expressed in onion epidermal cells. Overexpression of FeIREG1 in Arabidopsis resulted in increased Al tolerance, but did not alter the tolerance to Cd, Co and Fe. The tolerance to Ni was slightly enhanced in the overexpression lines. Mineral analysis showed that the accumulation of total root Al and other essential mineral elements was hardly altered in the overexpression lines. Taken together, our results suggest that FeIREG1 localized at the tonoplast plays an important role in internal Al detoxification by sequestering Al into the root vacuoles in buckwheat.

DOI： 10.1093/pcp/pcw065

Oryza sativa H+-ATPase (OSA) is Involved in the Regulation of Dumbbell-Shaped Guard Cells of Rice

Yosuke Toda, Yin Wang, Akira Takahashi, Yuya Kawai, Yasuomi Tada, Naoki Yamaji, Jian Feng Ma, Motoyuki Ashikari, Toshinori Kinoshita

PLANT AND CELL PHYSIOLOGY 57 ( 6 ) 1220 - 1230 2016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：OXFORD UNIV PRESS

The stomatal apparatus consists of a pair of guard cells and regulates gas exchange between the leaf and atmosphere. In guard cells, blue light (BL) activates H+-ATPase in the plasma membrane through the phosphorylation of its penultimate threonine, mediating stomatal opening. Although this regulation is thought to be widely adopted among kidney-shaped guard cells in dicots, the molecular basis underlying that of dumbbell-shaped guard cells in monocots remains unclear. Here, we show that H+-ATPases are involved in the regulation of dumbbell-shaped guard cells. Stomatal opening of rice was promoted by the H+-ATPase activator fusicoccin and by BL, and the latter was suppressed by the H+-ATPase inhibitor vanadate. Using H+-ATPase antibodies, we showed the presence of phosphoregulation of the penultimate threonine in Oryza sativa H+-ATPases (OSAs) and localization of OSAs in the plasma membrane of guard cells. Interestingly, we identified one H+-ATPase isoform, OSA7, that is preferentially expressed among the OSA genes in guard cells, and found that loss of function of OSA7 resulted in partial insensitivity to BL. We conclude that H+-ATPase is involved in BL-induced stomatal opening of dumbbell-shaped guard cells in monocotyledon species.

DOI： 10.1093/pcp/pcw070

A Cation-Chloride Cotransporter Gene Is Required for Cell Elongation and Osmoregulation in Rice

Zhi Chang Chen, Naoki Yamaji, Miho Fujii-Kashino, Jian Feng Ma

PLANT PHYSIOLOGY 171 ( 1 ) 494 - 507 2016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：AMER SOC PLANT BIOLOGISTS

Rice (Oryza sativa) is characterized by having fibrous root systems; however, the molecular mechanisms underlying the root development are not fully understood. Here, we isolated a rice mutant with short roots and found that the mutant had a decreased cell size of the roots and shoots compared with wild-type rice. Map-based cloning combined with whole-genome sequencing revealed that a single nucleotide mutation occurred in a gene, which encodes a putative cation-chloride cotransporter (OsCCC1). Introduction of OsCCC1 cDNA into the mutant rescued the mutant growth, indicating that growth defects of both the roots and shoots are caused by loss of function of OsCCC1. Physiological analysis showed that the mutant had a lower concentration of Cl- and K+ and lower osmolality in the root cell sap than the wild type at all KCl supply conditions tested; however, the mutant only showed a lower Na+ concentration at high external Na+. Expression of OsCCC1 in yeast increased accumulation of K+, Na+, and Cl-. The expression of OsCCC1 was found in both the roots and shoots, although higher expression was found in the root tips. Furthermore, the expression in the roots did not respond to different Na+, K+, and Cl- supply. OsCCC1 was expressed in all cells of the roots, leaf, and basal node. Immunoblot analysis revealed that OsCCC1 was mainly localized to the plasma membrane. These results suggest that OsCCC1 is involved in the cell elongation by regulating ion (Cl-, K+, and Na+) homeostasis to maintain cellular osmotic potential.

DOI： 10.1104/pp.16.00017

Functional Analysis of a MATE Gene OsFRDL2 Revealed its Involvement in Al-Induced Secretion of Citrate, but a Lower Contribution to Al Tolerance in Rice

Kengo Yokosho, Naoki Yamaji, Miho Fujii-Kashino, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 57 ( 5 ) 976 - 985 2016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：OXFORD UNIV PRESS

The multidrug and toxic compound extrusion (MATE) transporters represent a large transporter family in plants, but the role of most genes in this family has not been examined. We functionally characterized a MATE family member, OsFRDL2, in rice (Oryza sativa). OsFRDL2 showed an efflux transport activity for citrate when it was expressed in both Xenopus oocytes and cultured tobacco cells. OsFRDL2 was mainly expressed in the roots and its expression was not induced by iron (Fe) deficiency, but it was rapidly up-regulated by aluminum (Al). Furthermore, the expression of OsFRDL2 was regulated by ART1, a C2H2-type zinc-finger transcription factor for Al tolerance. OsFRDL2 protein was localized at unidentified vesicles in the cytosol, but not co-localized with either mitochondria or peroxisomes when expressed in both onion epidermal cells and cultured tobacco cells. Knockout of OsFRDL2 decreased Al-induced secretion of citrate from the roots, but did not affect the internal citrate concentration. The Al-induced inhibition of root elongation was similar between the OsFRDL2 knockout line and its wild-type rice. Knockout of OsFRDL2 did not affect the translocation of Fe from the roots to the shoots. A double mutant between osfrdl2 and osfrdl4 or osfrdl1 did not further decrease the Al-induced citrate secretion and Fe translocation compared with the single mutant. Collectively, our results indicate that although OsFRDL2 is involved in the Al-induced secretion of citrate, its contribution to high Al tolerance is relatively small in rice.

DOI： 10.1093/pcp/pcw026

Silicon decreases both uptake and root-to-shoot translocation of manganese in rice

Jing Che, Naoki Yamaji, Ji Feng Shao, Jian Feng Ma, Ren Fang Shen

JOURNAL OF EXPERIMENTAL BOTANY 67 ( 5 ) 1535 - 1544 2016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

Silicon (Si) is known to alleviate manganese (Mn) toxicity in a number of plant species; however, the mechanisms responsible for this effect are poorly understood. Here, we investigated the interaction between Si and Mn in rice (Oryza sativa) by using a mutant defective in Si uptake. Silicon alleviated Mn toxicity in the wild-type (WT) rice, but not in the mutant exposed to high Mn. The Mn concentration in the shoots was decreased, but that in the roots was increased by Si in the WT. In contrast, the Mn concentration in the roots and shoots was unaffected by Si in the mutant. Furthermore, Si supply resulted in an increased Mn in the root cell sap, decreased Mn in the xylem sap in the WT, but these effects of Si were not observed in the mutant. A short-term labelling experiment with Mn-54 showed that the uptake of Mn was similar between plants with and without Si and between WT and the mutant. However, Si decreased root-to-shoot translocation of Mn in the WT, but not in the mutant. The expression of a Mn transporter gene for uptake, OsNramp5, was unaffected by a short exposure (< 1 d) to Si, but down-regulated by relatively long-term exposure to Si in WT. In contrast, the expression of OsNramp5 was unaffected by Si in the mutant. These results indicated that Si-decreased Mn accumulation results from both Si-decreased root-to-shoot translocation of Mn, probably by the formation of Mn-Si complex in root cells, and uptake by down-regulating Mn transporter gene.

DOI： 10.1093/jxb/erv545

OsHKT1;4-mediated Na+ transport in stems contributes to Na+ exclusion from leaf blades of rice at the reproductive growth stage upon salt stress

Kei Suzuki, Naoki Yamaji, Alex Costa, Eiji Okuma, Natsuko I. Kobayashi, Tatsuhiko Kashiwagi, Maki Katsuhara, Cun Wang, Keitaro Tanoi, Yoshiyuki Murata, Julian I. Schroeder, Jian Feng Ma, Tomoaki Horie

BMC PLANT BIOLOGY 16 ( 1 ) 2016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：BMC

Background: Na+ exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to mediate leaf blade-Na+ exclusion upon salinity stress via Na+-selective transport. Multiple HKT1 transporters are known to function in rice (Oryza sativa). However, the ion transport function of OsHKT1;4 and its contribution to the Na+ exclusion mechanism in rice remain to be elucidated.Results: Here, we report results of the functional characterization of the OsHKT1; 4 transporter in rice. OsHKT1; 4 mediated robust Na+ transport in Saccharomyces cerevisiae and Xenopus laevis oocytes. Electrophysiological experiments demonstrated that OsHKT1; 4 shows strong Na+ selectivity among cations tested, including Li+, Na+, K+, Rb+, Cs+, and NH4+, in oocytes. A chimeric protein, EGFP-OsHKT1;4, was found to be functional in oocytes and targeted to the plasma membrane of rice protoplasts. The level of OsHKT1; 4 transcripts was prominent in leaf sheaths throughout the growth stages. Unexpectedly however, we demonstrate here accumulation of OsHKT1;4 transcripts in the stem including internode II and peduncle in the reproductive growth stage. Moreover, phenotypic analysis of OsHKT1;4 RNAi plants in the vegetative growth stage revealed no profound influence on the growth and ion accumulation in comparison with WT plants upon salinity stress. However, imposition of salinity stress on the RNAi plants in the reproductive growth stage caused significant Na+ overaccumulation in aerial organs, in particular, leaf blades and sheaths. In addition, Na-22(+) tracer experiments using peduncles of RNAi and WT plants suggested xylem Na+ unloading by OsHKT1;4.Conclusions: Taken together, our results indicate a newly recognized function of OsHKT1;4 in Na+ exclusion in stems together with leaf sheaths, thus excluding Na+ from leaf blades of a japonica rice cultivar in the reproductive growth stage, but the contribution is low when the plants are in the vegetative growth stage.

DOI： 10.1186/s12870-016-0709-4

Toxic Heavy Metal and Metalloid Accumulation in Crop Plants and Foods

Stephan Clemens, Jian Feng Ma

ANNUAL REVIEW OF PLANT BIOLOGY, VOL 67 67 489 - 512 2016年

記述言語：英語出版者・発行元：ANNUAL REVIEWS

Arsenic, cadmium, lead, and mercury are toxic elements that are almost ubiquitously present at low levels in the environment because of anthropogenic influences. Dietary intake of plant-derived food represents a major fraction of potentially health-threatening human exposure, especially to arsenic and cadmium. In the interest of better food safety, it is important to reduce toxic element accumulation in crops. A molecular understanding of the pathways responsible for this accumulation can enable the development of crop varieties with strongly reduced concentrations of toxic elements in their edible parts. Such understanding is rapidly progressing for arsenic and cadmium but is in its infancy for lead and mercury. Basic discoveries have been made in Arabidopsis, rice, and other models, and most advances in crops have been made in rice. Proteins mediating the uptake of arsenic and cadmium have been identified, and the speciation and biotransformations of arsenic are now understood. Factors controlling the efficiency of root-to-shoot translocation and the partitioning of toxic elements through the rice node have also been identified.

DOI： 10.1146/annurev-arplant-043015-112301

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18