研究者詳細 - 馬　建鋒

論文 - 馬　建鋒

分割表示 344 件中 101 - 120 件目／全件表示 >>

Effective reduction of cadmium accumulation in rice grain by expressing OsHMA3 under the control of the OsHMA2 promoter 査読

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

JOURNAL OF EXPERIMENTAL BOTANY 69 ( 10 ) 2743 - 2752 2018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：OXFORD UNIV PRESS

Reducing cadmium (Cd) accumulation in rice grain is an important issue for human health. The aim of this study was to manipulate both expression and tissue localization of OsHMA3, a tonoplast-localized Cd transporter, in the roots by expressing it under the control of the OsHMA2 promoter, which shows high expression in different organs including roots, nodes, and shoots. In two independent transgenic lines, the expression of OsHMA3 was significantly enhanced in all organs compared with non-transgenic rice. Furthermore, OsHMA3 protein was detected in the root pericycle cells and phloem region of both the diffuse vascular bundle and the enlarged vascular bundle of the nodes. At the vegetative stage, the Cd concentration in the shoots and xylem sap of the transgenic rice was significantly decreased, but that of the whole roots and root cell sap was increased. At the reproductive stage, the concentration of Cd, but not other essential metals, in the brown rice of transgenic lines was decreased to less than one-tenth that of the non-transgenic rice. These results indicate that expression of OsHMA3 under the control of the OsHMA2 promoter can effectively reduce Cd accumulation in rice grain through sequestering more Cd into the vacuoles of various tissues.

DOI： 10.1093/jxb/ery107

Transport system of mineral elements in rice

Namiki Mitani-Ueno, Naoki Yamaji, Jian Feng Ma

Rice Genomics, Genetics and Breeding 223 - 240 2018年3月

掲載種別：論文集(書籍)内論文

Plant requires 14 mineral elements for their growth and development. These elements in the soil are taken up by the roots, translocated from the roots to the shoots, and distributed to different organs depending on their demands (Marschner P, Mineral nutrition of higher plants, 3rd edn. Academic, London, 2012). In addition to these essential elements, toxic elements such as Cd and As are also transported from the soils to aboveground parts. All these processes require various transporters (membrane proteins). During the last decades, a number of transporters for uptake, translocation, and distribution of mineral elements have been identified, especially in model plants such as Arabidopsis and rice; however, most transporters remain to be identified. In this chapter, transporters identified so far in rice are described, and the regulation mechanisms of transporters in response to environmental changes are also discussed.

DOI： 10.1007/978-981-10-7461-5_13

Saving Water and Associated Energy from Distribution Networks by Considering Landscape Factors in Pressure Management and Use of District Metered Areas

Q. Xu, Q. W. Chen, S. P. Zhao, K. Liu, J. F. Ma

JOURNAL OF ENVIRONMENTAL INFORMATICS 31 ( 1 ) 65 - 73 2018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：INT SOC ENVIRON INFORM SCI

Controlling water loss in distribution systems is attracting increasing interest due to our increasingly limited water resources, exacerbated by rapid population growth, fast urbanization and climate change. Much has been invested in the management of water distribution networks to reduce water loss. However, the efficiency of management measures depends on spatiotemporal patterns of water loss, which are significantly influenced by the urban landscape. It is therefore important to consider urban landscape factors when designing and operating water distribution networks in order to reduce water loss and energy consumption. We investigated how the urban landscape, in particular urban topography and layout of water end users, impacts water loss and energy consumption. Topography was found to significantly influence the spatial pattern of average water pressure, while layout of end users influenced temporal variation of water pressure. A two-level water distribution network operating scheme (PMZ-DMA) was proposed to account for the influences of the two urban landscape factors. Application of the scheme efficiently reduced water loss, thereby generating significant environmental benefits, including reduction of energy consumption and greenhouse gas emissions.

DOI： 10.3808/jei.201700361

Preferential Distribution of Boron to Developing Tissues Is Mediated by the Intrinsic Protein OsNIP3 査読

Ji Feng Shao, Naoki Yamaji, Xin Wei Liu, Kengo Yokosho, Ren Fang Shen, Jian Feng Ma

PLANT PHYSIOLOGY 176 ( 2 ) 1739 - 1750 2018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：AMER SOC PLANT BIOLOGISTS

Boron is especially required for the growth of meristem and reproductive organs, but the molecular mechanisms underlying the preferential distribution of B to these developing tissues are poorly understood. Here, we show evidence that a member of nodulin 26-like intrinsic protein (NIP), OsNIP3; 1, is involved in this preferential distribution in rice (Oryza sativa). OsNIP3; 1 was highly expressed in the nodes and its expression was up-regulated by B deficiency, but down-regulated by high B. OsNIP3; 1 was polarly localized at the xylem parenchyma cells of enlarged vascular bundles of nodes facing toward the xylem vessels. Furthermore, this protein was rapidly degraded within a few hours in response to high B. Knockout of this gene hardly affected the uptake and root-to-shoot translocation of B, but altered B distribution in different organs in the above-ground parts, decreased distribution of B to the new leaves, and increased distribution to the old leaves. These results indicate that OsNIP3; 1 located in the nodes is involved in the preferential distribution of B to the developing tissues by unloading B from the xylem in rice and that it is regulated at both transcriptional and protein level in response to external B level.

DOI： 10.1104/pp.17.01641

OsNRT2.4 encodes a dual-affinity nitrate transporter and functions in nitrate-regulated root growth and nitrate distribution in rice 査読

Jia Wei, Yi Zheng, Huimin Feng, Hongye Qu, Xiaorong Fan, Naoki Yamaji, Jian Feng Ma, Guohua Xu

JOURNAL OF EXPERIMENTAL BOTANY 69 ( 5 ) 1095 - 1107 2018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：OXFORD UNIV PRESS

Plant NRT2 nitrate transporters commonly require a partner protein, NAR2, for transporting nitrate at low concentrations, but their role in plants is not well understood. In this study, we characterized the gene for one of these transporters in the rice genome, OsNRT2.4, in terms of its activity and roles in rice grown in environments with different N supply. In Xenopus oocytes, OsNRT2.4 alone without OsNAR2 co-expression facilitated nitrate uptake showing biphasic kinetics at a wide concentration range, with high- and low-affinity K-M values of 0.15 and 4 mM, respectively. OsNRT2.4 did not have nitrate efflux or IAA influx activity. In rice roots, OsNRT2.4 was expressed mainly in the base of lateral root primordia. Knockout of OsNRT2.4 decreased lateral root number and length, and the total N uptake per plant at both 0.25 and 2.5 mM NO3- levels. In the shoots, OsNRT2.4 was expressed mainly in vascular tissues, and its knockout decreased the growth and NO3--N distribution. Knockout of OsNRT2.4, however, did not affect rice growth and N uptake under conditions without N or with only NH4+ supply. We conclude that OsNRT2.4 functions as a dual-affinity nitrate transporter and is required for nitrate-regulated root and shoot growth of rice.

DOI： 10.1093/jxb/erx486

Silicon accumulated in the shoots results in down-regulation of phosphorus transporter gene expression and decrease of phosphorus uptake in rice

An Yong Hu, Jing Che, Ji Feng Shao, Kengo Yokosho, Xue Qiang Zhao, Ren Fang Shen, Jian Feng Ma

PLANT AND SOIL 423 ( 1-2 ) 317 - 325 2018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：SPRINGER

Silicon (Si) as a beneficial element can improve nutrient imbalance, but the molecular mechanism for this effect is poorly understood. The objective of this study is to examine the mechanism underlying Si-induced decrease of phosphorus (P) uptake in rice (Oryza sativa) at adequate/high P supply.A rice mutant (lsi1) defective in Si uptake and its wild type (cv. Oochikara) were used. The P uptake was compared in the presence and absence of Si and the expression of Pi transporter genes was quantified.Si addition in the nutrient solution significantly decreased shoot P concentration and uptake in the WT, but not in lsi1 mutant at two P levels, adequate (90 mu M) and high (210 mu M). Neither the root-to-shoot translocation of P nor the P distribution in different organs was altered by Si in both WT and lsi1. Heterogeneous expression of Lsi1 in Xenopus oocyte did not show transport activity for Pi. The expression of Pi transporter genes (OsPT1, 2 and 8) in the roots was hardly affected by Si in both WT and lsi1, but that of OsPT6 was down-regulated by Si in the WT roots, but not in the lsi1 roots. Furthermore, a split root experiment showed that Si accumulated in the shoots suppressed the expression of OsPT6. In rice grown in paddy field, lsi1 showed higher P concentration in the straw, husk and brown rice than the WT.Si decreased P uptake through down-regulating the expression of P transporter gene, OsPT6 in rice and Si accumulated in the shoot is required for this down-regulation.

DOI： 10.1007/s11104-017-3512-6

T-DNA Tagging-Based Gain-of-Function of OsHKT1;4 Reinforces Na Exclusion from Leaves and Stems but Triggers Na Toxicity in Roots of Rice Under Salt Stress 査読

Yuuka Oda, Natsuko I. Kobayashi, Keitaro Tanoi, Jian Feng Ma, Yukiko Itou, Maki Katsuhara, Takashi Itou, Tomoaki Horie

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES 19 ( 1 ) 2018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：MDPI

The high affinity K+ transporter 1;4 (HKT1;4) in rice (Oryza sativa), which shows Na+ selective transport with little K+ transport activity, has been suggested to be involved in reducing Na in leaves and stems under salt stress. However, detailed physiological roles of OsHKT1;4 remain unknown. Here, we have characterized a transfer DNA (T-DNA) insertion mutant line of rice, which overexpresses OsHKT1;4, owing to enhancer elements in the T-DNA, to gain an insight into the impact of OsHKT1;4 on salt tolerance of rice. The homozygous mutant (the O/E line) accumulated significantly lower concentrations of Na in young leaves, stems, and seeds than the sibling WT line under salt stress. Interestingly, however, the mutation rendered the O/E plants more salt sensitive than WT plants. Together with the evaluation of biomass of rice lines, rhizosphere acidification assays using a pH indicator bromocresol purple and (NaCl)-Na-22 tracer experiments have led to an assumption that roots of O/E plants suffered heavier damages from Na which excessively accumulated in the root due to increased activity of Na+ uptake and Na+ exclusion in the vasculature. Implications toward the application of the HKT1-mediated Na+ exclusion system to the breeding of salt tolerant crop cultivars will be discussed.

DOI： 10.3390/ijms19010235

Both retrotransposon insertion and demethylation regulate aluminum tolerance of European barley for postdomestication expansion to acid soil.

Fujii-Kashino, M, Yamaji, N, Yamane, M, Saisho, D, Sato, K, Ma, J. F

Plant Physiology 2018年

Rice reduces Mn uptake in response to Mn stress 査読

Yuta Tsunemitsu, Naoki Yamaji, Jian Feng Ma, Shin-ichiro Kato, Kozo Iwasaki, Daisei Ueno

PLANT SIGNALING & BEHAVIOR 13 ( 1 ) 2018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：TAYLOR & FRANCIS INC

Rice (Oryza sativa L) is one of the most Mn-tolerant crops that can grow in submerged paddy fields, where the Mn concentration in soil solution is very high due to reduction. Although a large part of Mn is transferred from the roots to the shoot in rice, the roots are constantly exposed to high Mn concentrations in submerged paddies. Thus, mechanisms for preventing Mn overaccumulation in the cytoplasm of root cells are necessary. Recently, we showed that two cation diffusion facilitators, MTP8.1 and MTP8.2, play a crucial role in Mn tolerance in rice roots by sequestering Mn in vacuoles. Moreover, we observed that disruption of MTP8.1 and MTP8.2 resulted in reduced Mn accumulation under excess Mn. In the present study, we examined the effects of disruption of MTP8.1 and MTP8.2 on Mn uptake and determined that this phenotype is caused by a rapid and significant reduction of Mn uptake in response to excess Mn. Previously, we showed that Mn export from root cells through MTP9 was promoted by high Mn. Together, these findings suggest that optimal Mn concentration in rice roots is maintained by reduced uptake, vacuolar sequestration, and extrusion by cation diffusion facilitators.

DOI： 10.1080/15592324.2017.1422466

Two MATE Transporters with Different Subcellular Localization are Involved in Al Tolerance in Buckwheat

Gui Jie Lei, Kengo Yokosho, Naoki Yamaji, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 58 ( 12 ) 2179 - 2189 2017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

Buckwheat (Fagopyrum esculentum) shows high tolerance to aluminum (Al) toxicity, but the molecular mechanisms responsible for this high Al tolerance are still poorly understood. Here, we investigated the involvement of two MATE (multi-drug and toxic compound extrusion) genes in Al tolerance. Both FeMATE1 and FeMATE2 showed efflux transport activity for citrate, but not for oxalate when expressed in Xenopus oocytes. A transient assay with buckwheat leaf protoplasts using green fluorescent protein (GFP) fusion showed that FeMATE1 was mainly localized to the plasma membrane, whereas FeMATE2 was localized to the trans-Golgi and Golgi. The expression of FeMATE1 was induced by Al only in the roots, but that of FeMATE2 was up-regulated in both the roots and leaves. Furthermore, the expression of both genes only responded to Al toxicity, but not to other stresses including low pH, cadmium (Cd) and lanthanum (La). Heterologous expression of FeMATE1 or FeMATE2 in the Arabidopsis mutant atmate partially rescued its Al tolerance. Expression of FeMATE1 also partially recovered the Al-induced secretion of citrate in the transgenic lines, whereas expression of FeMATE2 did not complement the citrate secretion. Further physiological analysis showed that buckwheat roots also secreted citrate in addition to oxalate in response to Al in a dose-responsive manner. Taken together, our results indicate that FeMATE1 is involved in the Al-activated citrate secretion in the roots, while FeMATE2 is probably responsible for transporting citrate into the Golgi system for the internal detoxification of Al in the roots and leaves of buckwheat.

DOI： 10.1093/pcp/pcx152

Root cone angle is enlarged in docs1 LRR-RLK mutants in rice

M. Bettembourg, M. Dal-Soglio, C. Bureau, A. Vernet, A. Dardoux, M. Portefaix, M. Bes, D. Meynard, D. Mieulet, B. Cayrol, C. Perin, B. Courtois, J. F. Ma, A. Dievart

RICE 10 ( 1 ) 453 - 459 2017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：SPRINGER

The DEFECTIVE IN OUTER CELL LAYER SPECIFICATION 1 (DOCS1) gene belongs to the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) subfamily. It has been discovered few years ago in Oryza sativa (rice) in a screen to isolate mutants with defects in sensitivity to aluminum. The c68 (docs1-1) mutant possessed a nonsense mutation in the C-terminal part of the DOCS1 kinase domain.
We have generated a new loss-of-function mutation in the DOCS1 gene (docs1-2) using the CRISPR-Cas9 technology. This new loss-of-function mutant and docs1-1 present similar phenotypes suggesting the original docs1-1 was a null allele. Besides the aluminum sensitivity phenotype, both docs1 mutants shared also several root phenotypes described previously: less root hairs and mixed identities of the outer cell layers. Moreover, our new results suggest that DOCS1 could also play a role in root cap development. We hypothesized these docs1 root phenotypes may affect gravity responses. As expected, in seedlings, the early gravitropic response was delayed. Furthermore, at adult stage, the root gravitropic set angle of docs1 mutants was also affected since docs1 mutant plants displayed larger root cone angles.
All these observations add new insights into the DOCS1 gene function in gravitropic responses at several stages of plant development.

DOI： 10.1186/s12284-017-0190-1

A GDSL-motif esterase/acyltransferase/lipase is responsible for leaf water retention in barley

Chao Li, Guoxiong Chen, Kohei Mishina, Naoki Yamaji, Jian Feng Ma, Fumiko Yukuhiro, Akemi Tagiri, Cheng Liu, Mohammad Pourkheirandish, Nadia Anwar, Masaru Ohta, Pengshan Zhao, Udda Lundqvist, Xinrong Li, Takao Komatsuda

PLANT DIRECT 1 ( 5 ) 1 - 12 2017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：JOHN WILEY & SONS LTD

The hydrophobic cuticle covers the surface of the most aerial organs of land plants. The barley mutant eceriferum-zv (cer-zv), which is hypersensitive to drought, is unable to accumulate a sufficient quantity of cutin in its leaf cuticle. The mutated locus has been mapped to a 0.02 cM segment in the pericentromeric region of chromosome 4H. As a map-based cloning approach to isolate the gene was therefore considered unlikely to be feasible, a comparison was instead made between the transcriptomes of the mutant and the wild type. In conjunction with extant genomic information, on the basis of predicted functionality, only two genes were considered likely to encode a product associated with cutin formation. When eight independent cer-zv mutant alleles were resequenced with respect to the two candidate genes, it was confirmed that the gene underlying the mutation in each allele encodes a Gly-Asp-Ser-Leu (GDSL)-motif esterase/acyltransferase/lipase. The gene was transcribed in the epidermis, and its product was exclusively deposited in cell wall at the boundary of the cuticle in the leaf elongation zone, coinciding with the major site of cutin deposition. CER-ZV is speculated to function in the deposition of cutin polymer. Its homologs were found in green algae, moss, and euphyllophytes, indicating that it is highly conserved in plant kingdom.

DOI： 10.1002/pld3.25

Detection of quantitative trait loci controlling grain zinc concentration using Australian wild rice, Oryza meridionalis, a potential genetic resource for biofortification of rice

Ryo Ishikawa, Masahide Iwata, Kenta Taniko, Gotaro Monden, Naoya Miyazaki, Chhourn Orn, Yuki Tsujimura, Shusaku Yoshida, Jian Feng Ma, Takashige Ishii

PLOS ONE 12 ( 10 ) e0187224 2017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：PUBLIC LIBRARY SCIENCE

Zinc (Zn) is one of the essential mineral elements for both plants and humans. Zn deficiency in human is one of the major causes of hidden hunger, a serious health problem observed in many developing countries. Therefore, increasing Zn concentration in edible part is an important issue for improving human Zn nutrition. Here, we found that an Australian wild rice O. meridionalis showed higher grain Zn concentrations compared with cultivated and other wild rice species. The quantitative trait loci (QTL) analysis was then performed to identify the genomic regions controlling grain Zn levels using backcross recombinant inbred lines derived from O. sativa 'Nipponbare' and O. meridionalis W1627. Four QTLs responsible for high grain Zn were detected on chromosomes 2, 9, and 10. The QTL on the chromosome 9 (named qGZn9), which showed the largest effect on grain Zn concentration was confirmed with the introgression line, which had a W1627 chromosomal segment covering the qGZn9 region in the genetic background of O. sativa 'Nipponbare'. Fine mapping of this QTL resulted in identification of two tightly linked loci, qGZn9a and qGZn9b. The candidate regions of qGZn9a and qGZn9b were estimated to be 190 and 950 kb, respectively. Furthermore, we also found that plants having a wild chromosomal segment covering qGZn9a, but not qGZn9b, is associated with fertility reduction. qGZn9b, therefore, provides a valuable allele for breeding rice with high Zn in the grains.

DOI： 10.1371/journal.pone.0187224

Node-controlled allocation of mineral elements in Poaceae

Naoki Yamaji, Jian Feng Ma

CURRENT OPINION IN PLANT BIOLOGY 39 18 - 24 2017年10月

記述言語：英語出版者・発行元：CURRENT BIOLOGY LTD

Mineral elements taken up by the roots will be delivered to different organs and tissues depending on their requirements. In Poaceae, this selective distribution is mainly mediated in the nodes, which have highly developed and fully organized vascular systems. Inter-vascular transfer of mineral elements from enlarged vascular bundles to diffuse vascular bundles is required for their preferential distribution to developing tissues and reproductive organs. A number of transporters involved in this inter-vascular transfer processes have been identified mainly in rice. They are localized at the different cell layers and form an efficient machinery within the node. Furthermore, some these transporters show rapid response to the environmental changes of mineral elements at the protein level. In addition to the node-based transporters, distinct nodal structures including enlarged xylem area, folded plasma membrane of xylem transfer cells and presence of an apoplastic barrier are also required for the efficient inter-vascular transfer. Manipulation of node-based transporters will provide a novel breeding target to improve nutrient use efficiency, productivity, nutritional value and safety in cereal crops.

DOI： 10.1016/j.pbi.2017.05.002

Editorial: Role of Silicon in Plants

Rupesh K. Deshmukh, Jian F. Ma, Richard R. Belanger

FRONTIERS IN PLANT SCIENCE 8 1858 2017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：FRONTIERS MEDIA SA

Silicon (Si), the second most abundant element on earth surface, is rapidly gaining attention in agriculture because of its many beneficial effects for plants. Hundreds of studies performed with several plant species and under diverse growth conditions have demonstrated the favorable benefits of Si fertilization, particularly in alleviating biotic and abiotic stresses (Fauteux et al., 2005, 2006). Ever since the breakthrough discovery of genes explaining the molecular mechanisms of Si uptake and transport in plants a decade ago (Ma et al., 2006, 2007), many research endeavors have tried to explain how and why Si presence in plants confers advantages. The most challenging aspect consists in defining a mechanistic model explaining the precise mechanisms involved in Si-derived stress tolerance. While many hypotheses have been proposed, there is no conclusive evidence showing exactly how Si plays a role in stress tolerance. Current efforts to resolve this enigma involve comprehensive analyses of the effect of Si supplementation on various abiotic and biotic stresses, biochemical and physiological parameters, mineral co-localization and distribution, and transcriptomic and metabolomic responses. At the same time, research activities are focused on improving Si fertilization and Si sources for crop cultivation. The present research topic compiles many aspects helpful to generate a better understanding required for the optimal utilization of Si to promote sustainable development and climate-adapted cropping.

DOI： 10.3389/fpls.2017.01858

Silicon reduces cadmium accumulation by suppressing expression of transporter genes involved in cadmium uptake and translocation in rice

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

JOURNAL OF EXPERIMENTAL BOTANY 68 ( 20 ) 5641 - 5651 2017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：OXFORD UNIV PRESS

Silicon (Si) alleviates cadmium (Cd) toxicity and accumulation in a number of plant species, but the exact molecular mechanisms responsible for this effect are still poorly understood. Here, we investigated the effect of Si on Cd toxicity and accumulation in rice (Oryza sativa) by using two mutants (lsi1 and lsi2) defective in Si uptake and their wild types (WTs). Root elongation was decreased with increasing external Cd concentrations in both WTs and mutants, but Si did not show an alleviative effect on Cd toxicity in all lines. By contrast, the Cd concentration in both the shoots and roots was decreased by Si in the WTs, but not in the mutants. Furthermore, Si supply resulted in a decreased Cd concentration in the root cell sap and xylem sap in the WTs, but not in the mutants. Pre-treatment with Si also decreased Cd accumulation in the WTs, but not in the mutants. Silicon slightly decreased Cd accumulation in the cell wall of the roots. The expression level of OsNramp5 and OsHMA2 was down-regulated by Si in the WTs, but not in the mutants. These results indicate that the Si-decreased Cd accumulation was caused by down-regulating transporter genes involved in Cd uptake and translocation in rice.

DOI： 10.1093/jxb/erx364

The Tonoplast-Localized Transporter MTP8.2 Contributes to Manganese Detoxification in the Shoots and Roots of Oryza sativa L.

Yuma Takemoto, Yuta Tsunemitsu, Miho Fujii-Kashino, Namiki Mitani-Ueno, Naoki Yamaji, Jian Feng Ma, Shin-ichiro Kato, Kozo Iwasaki, Daisei Ueno

PLANT AND CELL PHYSIOLOGY 58 ( 9 ) 1573 - 1582 2017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：OXFORD UNIV PRESS

Manganese (Mn) cation diffusion facilitators (Mn-CDFs) play important roles in the Mn homeostasis of plants. In rice, the tonoplast-localized Mn-CDF metal tolerance protein 8.1 (MTP8.1) is involved in Mn detoxification in the shoots. This study functionally characterized the Mn-CDF MTP8.2 and determined its contribution to Mn tolerance. MTP8.2 was found to share 68% identity with MTP8.1 and was expressed in both the shoots and roots, but its transcription level was lower than that of MTP8.1. Transient expression of the MTP8.2:green fluorescent protein (GFP) fusion protein and immunoblotting studies indicated that MTP8.2 was also localized to the tonoplast. MTP8.2 expression in yeast conferred tolerance to Mn but not to Fe, Zn, Co, Ni or Cd. MTP8.2 knockdown caused further growth reduction of shoots and roots in the mtp8.1 mutant, which already exhibits stunted growth under conditions of excess Mn. In the presence of high Mn, the MTP8.2 knockdown lines of the mtp8.1 mutant showed lower root Mn concentrations, as well as lower root: total Mn ratios, than those of wild-type rice and the mtp8.1 mutant. These findings indicate that MTP8.2 mediates Mn tolerance along with MTP8.1 through the sequestration of Mn into the shoot and root vacuoles.

DOI： 10.1093/pcp/pcx082

Functional characterization of two half-size ABC transporter genes in aluminium-accumulating buckwheat

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

NEW PHYTOLOGIST 215 ( 3 ) 1080 - 1089 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：WILEY

Buckwheat (Fagopyrum esculentum Moench) is able to detoxify high aluminium (Al) internally by sequestering it to the vacuoles in the leaves; however, the molecular mechanisms underlying this sequestration are unknown.We performed proteomic analysis with the leaf tonoplast-rich fraction and identified two half-size ABC transporters; FeASL1.1 and FeALS1.2. We investigated the gene expression patterns and subcellular localization. To demonstrate their physiological role, we expressed FeALS1.1 or FeALS1.2 in the Arabidopsis atals1 mutant under the control of AtALS1 promoter.FeALS1.1 expression was upregulated by Al in both the leaves and the roots, and its expression level in the roots was six times higher than its homologous gene (AtALS1) of Arabidopsis. FeALS1.2 expression, however, was not affected by Al but showed a 39 times higher expression level than AtALS1 in the leaves. When FeALS1.1 or FeALS1.2 was expressed in atals1, both of them recovered their Al tolerance through altering the subcellular localization of Al in root cells.Taken together, our results indicate that FeALS1.1 and FeALS1.2 are involved in the internal detoxification of Al in the roots and leaves, respectively, by sequestering Al into the vacuoles. Their high expression is probably required for high Al tolerance in buckwheat.

DOI： 10.1111/nph.14648

OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice

Natsuko I. Kobayashi, Naoki Yamaji, Hiroki Yamamoto, Kaoru Okubo, Hiroki Ueno, Alex Costa, Keitaro Tanoi, Hideo Matsumura, Miho Fujii-Kashino, Tomoki Horiuchi, Mohammad Al Nayef, Sergey Shabala, Gynheung An, Jian Feng Ma, Tomoaki Horie

PLANT JOURNAL 91 ( 4 ) 657 - 670 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：WILEY

Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+/Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+-selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent TDNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22 Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22 Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22 Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.

DOI： 10.1111/tpj.13595

A Magnesium Transporter OsMGT1 Plays a Critical Role in Salt Tolerance in Rice(1[OPEN])

Zhi Chang Chen, Naoki Yamaji, Tomoaki Horie, Jing Che, Jian Li, Gynheung An, Jian Feng Ma

PLANT PHYSIOLOGY 174 ( 3 ) 1837 - 1849 2017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

Salt stress is one of the major factors limiting rice (Oryza sativa) production globally. Although several transporters involved in salt tolerance have been identified in rice, the mechanisms regulating their transport activity are still poorly understood. Here, we show evidence that a rice Mg transporter OsMGT1 is required for salt tolerance probably by regulating transport activity of OsHKT1;5, a key transporter for the removal of Na+ from the xylem sap at the root mature zone. Knockout of OsMGT1 did not affect total Na uptake, but increased Na concentration in the shoots and xylem sap, resulting in a significant increase in salt sensitivity at low external Mg2+ concentration (20-200 mu M). However, such differences were abolished at a higher Mg2+ concentration (2 mM), although the total Na uptake was not altered. OsMGT1 was expressed in both the roots and shoots, but only that in the roots was moderately up-regulated by salt stress. Spatial expression analysis revealed that OsMGT1 was expressed in all root cells of the root tips but was highly expressed in the pericycle of root mature zone. OsMGT1 was also expressed in the phloem region of basal node, leaf blade, and sheath. When expressed in Xenopus laevis oocytes, the transport activity of OsHKT1;5 was enhanced by elevating external Mg2+ concentration. Furthermore, knockout of OsHKT1;5 in osmgt1 mutant background did not further increase its salt sensitivity. Taken together, our results suggest that Mg2+ transported by OsMGT1 in the root mature zone is required for enhancing OsHKT1;5 activity, thereby restricting Na accumulation to the shoots.

DOI： 10.1104/pp.17.00532

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