Faculty Profiles - MA Jian Feng

Papers - MA Jian Feng

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A polarly localized transporter for efficient manganese uptake in rice

Daisei Ueno, Akimasa Sasaki, Naoki Yamaji, Takaaki Miyaji, Yumi Fujii, Yuma Takemoto, Sawako Moriyama, Jing Che, Yoshinori Moriyama, Kozo Iwasaki, Jian Feng Ma

NATURE PLANTS 1 ( 12 ) 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Manganese is an essential metal for plant growth. A number of transporters involved in the uptake of manganese from soils, and its translocation to the shoot, have been identified in Arabidopsis and rice. However, the transporter responsible for the radial transport of manganese out of root exodermis and endodermis cells and into the root stele remains unknown. Here, we show that metal tolerance protein 9 (MTP9), a member of the cation diffusion facilitator family, is a critical player in this process in rice (Oryza sativa). We find that MTP9 is mainly expressed in roots, and that the resulting protein is localized to the plasma membrane of exo- and endodermis cells, at the proximal side of these cell layers (opposite the manganese uptake transporter Nramp5, which is found at the distal side). We demonstrate that MTP9 has manganese transport activity by expression in proteoliposomes and yeast, and show that knockout of MTP9 in rice reduces manganese uptake and its translocation to shoots. We conclude that at least in rice MTP9 is required for manganese translocation to the root stele, and thereby manganese uptake.

DOI： 10.1038/NPLANTS.2015.170

Genome-wide association mapping of cadmium accumulation in different organs of barley International journal

Dezhi Wu, Kazuhiro Sato, Jian Feng Ma

NEW PHYTOLOGIST 208 ( 3 ) 817 - 829 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

The threshold value of cadmium (Cd) concentration in grains of barley (Hordeum vulgare) is the lowest among cereal crops; however, it is poorly understood how Cd accumulation in barley grain is genetically controlled.We investigated genotypic variation in Cd accumulation of different organs in 100 accessions from a subset of the barley core collection using both hydroponic and Cd-contaminated soil culture. We also performed a genome-wide association (GWA) mapping for Cd accumulation in different organs.A large genotypic variation in the Cd concentration was found in all organs. There was a good correlation between shoot Cd of solution and soil culture, the shoot Cd and grain Cd, but no correlation between the root Cd and grain Cd. GWA mapping detected 9 quantitative trait loci (QTL) for root Cd, 21 for shoot Cd, 14 for root-to-shoot translocation and 15 for grain Cd. A common QTL for the shoot Cd and root-to-shoot translocation was found at 132.6 cM on chromosome 5H. Two major QTL for grain Cd were identified on chromosome 2H and chromosome 5H.The genetic variation in Cd accumulation and major QTL detected provide useful information helpful for cloning candidate genes for Cd accumulation and breeding low-Cd barley cultivars in future.

DOI： 10.1111/nph.13512

A node-localized transporter OsZIP3 is responsible for the preferential distribution of Zn to developing tissues in rice

Akimasa Sasaki, Naoki Yamaji, Namiki Mitani-Ueno, Miho Kashino, Jian Feng Ma

PLANT JOURNAL 84 ( 2 ) 374 - 384 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

Developing tissues such as meristem with low transpiration require high Zn levels for their active growth, but the molecular mechanisms underlying the preferential distribution to these tissues are poorly understood. We found that a member of the ZIP (ZRT, IRT-like protein), OsZIP3, showed high expression in the nodes of rice (Oryza sativa). Immunostaining revealed that OsZIP3 was localized at the xylem intervening parenchyma cells and xylem transfer cells of the enlarged vascular bundle in both basal and upper nodes. Neither OsZIP3 gene expression nor encoded protein was affected by either deficiency or toxic levels of Zn. Knockdown of OsZIP3 resulted in significantly reduced Zn levels in the shoot basal region containing the shoot meristem and elongating zone, but increased Zn levels in the transpiration flow. A short-term experiment with the Zn-67 stable isotope showed that more Zn was distributed to the lower leaves, but less to the shoot elongating zone and nodes in the knockdown lines compared with the wild-type rice at both the vegetative and reproductive growth stages. Taken together, OsZIP3 located in the node is responsible for unloading Zn from the xylem of enlarged vascular bundles, which is the first step for preferential distribution of Zn to the developing tissues in rice.Significance Statement Zinc homeostasis is achieved by regulating diverse zinc transporters. Here we show that the zinc transporter OsZIP3 mediates the first step leading to preferential distribution of zinc in developing tissues, by unloading zinc from the xylem of enlarged vascular bundles.

DOI： 10.1111/tpj.13005

Effect of in planta phosphorus on aluminum-induced inhibition of root elongation in wheat

Ji Feng Shao, Jing Che, Rong Fu Chen, Jian Feng Ma, Ren Fang Shen

PLANT AND SOIL 395 ( 1-2 ) 307 - 315 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Both aluminum (Al) toxicity and phosphorus (P) deficiency are limiting factors of crop production on acid soils. Although Al-P interaction has been extensively studied, the results are controversial. The aim of this study is to investigate the effect of in planta P on Al-induced inhibition of root elongation in wheat (Triticum aestivum L.).Roots of wheat (cv. Atlas 66) with different internal P concentrations were prepared by two methods; split-root and re-rooting in a hydroponic solution using three different P levels (0, 25 and 250 mu M) to avoid direct precipitation of Al-P in the solution. Al toxicity was evaluated by root elongation inhibition and callose induction. The Al and P concentrations in the root tips were also compared among different treatments.Both split-root and re-rooting methods generated roots with different P concentrations in the tips when exposed to different P levels. Lower P in the root tips resulted in less Al-induced inhibition of the root elongation, less callose content and less Al accumulation, while higher root P caused a higher Al-induced inhibition of the root elongation, increased callose content and Al accumulation in the root tips. Furthermore, Al in the root cell sap was not altered by different P concentrations, but Al in the root cell wall was increased with increasing in planta P concentrations.Al toxicity in wheat is associated with P in the root cell wall; lower root P enhanced Al tolerance, while higher root P aggravated Al toxicity in wheat.

DOI： 10.1007/s11104-015-2566-6

Orchestration of three transporters and distinct vascular structures in node for intervascular transfer of silicon in rice

Naoki Yamaji, Gen Sakurai, Namiki Mitani-Ueno, Jian Feng Ma

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 112 ( 36 ) 11401 - 11406 2015.9

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL ACAD SCIENCES

Requirement of mineral elements in different plant tissues is not often consistent with their transpiration rate; therefore, plants have developed systems for preferential distribution of mineral elements to the developing tissues with low transpiration. Here we took silicon (Si) as an example and revealed an efficient system for preferential distribution of Si in the node of rice (Oryza sativa). Rice is able to accumulate more than 10% Si of the dry weight in the husk, which is required for protecting the grains from water loss and pathogen infection. However, it has been unknown for a long time how this hyperaccumulation is achieved. We found that three transporters (Lsi2, Lsi3, and Lsi6) located at the node are involved in the intervascular transfer, which is required for the preferential distribution of Si. Lsi2 was polarly localized to the bundle sheath cell layer around the enlarged vascular bundles, which is next to the xylem transfer cell layer where Lsi6 is localized. Lsi3 was located in the parenchyma tissues between enlarged vascular bundles and diffuse vascular bundles. Similar to Lsi6, knockout of Lsi2 and Lsi3 also resulted in decreased distribution of Si to the panicles but increased Si to the flag leaf. Furthermore, we constructed a mathematical model for Si distribution and revealed that in addition to cooperation of three transporters, an apoplastic barrier localized at the bundle sheath cells and development of the enlarged vascular bundles in node are also required for the hyperaccumulation of Si in rice husk.

DOI： 10.1073/pnas.1508987112

Improving Nitrogen Use Efficiency in Rice through Enhancing Root Nitrate Uptake Mediated by a Nitrate Transporter, NRT1.1B

Zhi Chang Chen, Jian Feng Ma

JOURNAL OF GENETICS AND GENOMICS 42 ( 9 ) 463 - 465 2015.9

The role of nodes in arsenic storage and distribution in rice

Yi Chen, Katie L. Moore, Anthony J. Miller, Steve P. McGrath, Jian Feng Ma, Fang-Jie Zhao

JOURNAL OF EXPERIMENTAL BOTANY 66 ( 13 ) 3717 - 3724 2015.7

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Knowledge of arsenic (As) accumulation in rice (Oryza sativa L.) is important for minimizing As transfer to the food chain. The aim of this study was to investigate the role of rice nodes in As storage and distribution. Synchrotron mu X-ray fluorescence (mu-XRF) was used to map As distribution in the top node and internode of a lsi2 mutant defective in silicon/arsenite efflux carrier and its wild-type (WT) grown in soil. Lsi2 expression in different tissues during grain filling was investigated by quantitative RT-PCR. Arsenite or dimethylarsinic acid (DMA) was supplied to excised panicles to investigate the roles of Lsi2 and phytochelatins (PC) in As distribution. mu-XRF mapping revealed As storage in the phloem of different vascular bundles in the top node and internode. Soil-grown plants of lsi2 had markedly decreased As accumulation in the phloem compared with the WT. Lsi2 was strongly expressed, not only in the roots but also in the nodes. When excised panicles were exposed to As(III), the lsi2 mutant distributed more As to the node and flag leaf but less As to the grain compared with the WT, while there was no significant difference in DMA distribution. Inhibition of PC synthesis by L-buthionine-sulphoximine decreased As(III) deposition in the top node but increased As accumulation in the grain and flag leaf. The results suggest that rice nodes serve as a filter restricting As(III) distribution to the grain. Furthermore, Lsi2 plays a role in As(III) distribution in rice nodes and phytochelatins are important compounds for As(III) storage in the nodes.

DOI： 10.1093/jxb/erv164

Altered cell wall properties are responsible for ammonium-reduced aluminium accumulation in rice roots

Wei Wang, Xue Qiang Zhao, Rong Fu Chen, Xiao Ying Dong, Ping Lan, Jian Feng Ma, Ren Fang Shen

PLANT CELL AND ENVIRONMENT 38 ( 7 ) 1382 - 1390 2015.7

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

The phytotoxicity of aluminium (Al) ions can be alleviated by ammonium (NH4+) in rice and this effect has been attributed to the decreased Al accumulation in the roots. Here, the effects of different nitrogen forms on cell wall properties were compared in two rice cultivars differing in Al tolerance. An in vitroAl-binding assay revealed that neither NH4+ nor NO3- altered the Al-binding capacity of cell walls, which were extracted from plants not previously exposed to N sources. However, cell walls extracted from NH4+-supplied roots displayed lower Al-binding capacity than those from NO3--supplied roots when grown in non-buffered solutions. Fourier-transform infrared microspectroscopy analysis revealed that, compared with NO3--supplied roots, NH4+-supplied roots possessed fewer Al-binding groups (-OH and COO-) and lower contents of pectin and hemicellulose. However, when grown in pH-buffered solutions, these differences in the cell wall properties were not observed. Further analysis showed that the Al-binding capacity and properties of cell walls were also altered by pHs alone. Taken together, our results indicate that the NH4+-reduced Al accumulation was attributed to the altered cell wall properties triggered by pH decrease due to NH4+ uptake rather than direct competition for the cell wall binding sites between Al3+ and NH4+.Ammonium (NH4+) is known to alleviate Al toxicity by reducing Al accumulation in rice roots, but the responsible mechanisms are poorly understood. In this study, we found that the NH4+-reduced accumulation of Al was associated with decreased Al-binding groups (-OH and COO-) and contents of pectin and hemicellulose in both Al-tolerant and Al-sensitive rice cultivars. Furthermore, these alterations of cell wall properties were caused by pH decrease due to uptake of NH4+.

DOI： 10.1111/pce.12490

A cooperative system of silicon transport in plants

Jian Feng Ma, Naoki Yamaji

TRENDS IN PLANT SCIENCE 20 ( 7 ) 435 - 442 2015.7

Language：English Publisher：ELSEVIER SCIENCE LONDON

The high accumulation of silicon (Si) protects plants from biotic and abiotic stresses. Two different types of Si transporter [Low Silicon 1 (Lsi1) and 2 (Lsi2)] involved in the uptake and distribution of Si have been identified. Lsi1, a Si permeable channel, belongs to the Nod26-like major intrinsic protein (NIP) III subgroup of the aquaporin membrane protein family with a distinct selectivity, whereas Lsi2, an efflux Si transporter, belongs to an uncharacterized anion transporter family. These transporters are localized to the plasma membrane, but, in different plant species, show different expression patterns and tissue or cellular localizations that are associated with different levels of Si accumulation. A recent mathematical modeling study revealed that cooperation of Lsi1 and Lsi2, which show a polarized localization, is required for the efficient transport of Si in rice.

DOI： 10.1016/j.tplants.2015.04.007

In Silico Simulation Modeling Reveals the Importance of the Casparian Strip for Efficient Silicon Uptake in Rice Roots

Gen Sakurai, Akiko Satake, Naoki Yamaji, Namiki Mitani-Ueno, Masayuki Yokozawa, Francois Gabriel Feugier, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 56 ( 4 ) 631 - 639 2015.4

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Silicon (Si) uptake by the roots is mediated by two different transporters, Lsi1 (passive) and Lsi2 (active), in rice (Oryza sativa). Both transporters are polarly localized in the plasma membranes of exodermal (outer) and endodermal (inner) cells with Casparian strips. However, it is unknown how rice is able to take up large amounts of Si compared with other plants, and why rice Si transporters have a characteristic cellular localization pattern. To answer these questions, we simulated Si uptake by rice roots by developing a mathematical model based on a simple diffusion equation that also accounts for active transport by Lsi2. In this model, we calibrated the model parameters using in vivo experimental data on the Si concentrations in the xylem sap and a Monte Carlo method. In our simulation experiments, we compared the Si uptake between roots with various transporter and Casparian strip locations and estimated the Si transport efficiency of roots with different localization patterns and quantities of the Lsi transporters. We found that the Si uptake by roots that lacked Casparian strips was lower than that of normal roots. This suggests that the doublelayer structure of the Casparian strips is an important factor in the high Si uptake by rice. We also found that among various possible localization patterns, the most efficient one was that of the wild-type rice; this may explain the high Si uptake capacity of rice.

DOI： 10.1093/pcp/pcv017

The Rice CK2 Kinase Regulates Trafficking of Phosphate Transporters in Response to Phosphate Levels

Jieyu Chen, Yifeng Wang, Fei Wang, Jian Yang, Mingxing Gao, Changying Li, Yingyao Liu, Yu Liu, Naoki Yamaji, Jian Feng Ma, Javier Paz-Ares, Laurent Nussaume, Shuqun Zhang, Keke Yi, Zhongchang Wu, Ping Wu

PLANT CELL 27 ( 3 ) 711 - 723 2015.3

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC PLANT BIOLOGISTS

Phosphate transporters (PTs) mediate phosphorus uptake and are regulated at the transcriptional and posttranslational levels. In one key mechanism of posttranslational regulation, phosphorylation of PTs affects their trafficking from the endoplasmic reticulum (ER) to the plasma membrane. However, the kinase(s) mediating PT phosphorylation and the mechanism leading to ER retention of phosphorylated PTs remain unclear. In this study, we identified a rice (Oryza sativa) kinase subunit, CK2 beta 3, which interacts with PT2 and PT8 in a yeast two-hybrid screen. Also, the CK2 alpha 3/beta 3 holoenzyme phosphorylates PT8 under phosphate-sufficient conditions. This phosphorylation inhibited the interaction of PT8 with PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1, a key cofactor regulating the exit of PTs from the ER to the plasma membrane. Additionally, phosphorus starvation promoted CK2 beta 3 degradation, relieving the negative regulation of PT phosphorus-insufficient conditions. In accordance, transgenic expression of a nonphosphorylatable version of OsPT8 resulted in elevated levels of that protein at the plasma membrane and enhanced phosphorus accumulation and plant growth under various phosphorus regimes. Taken together, these results indicate that CK2 alpha 3/beta 3 negatively regulates PTs and phosphorus status regulates CK2 alpha 3/beta 3.

DOI： 10.1105/tpc.114.135335

Exploring the power of plants to overcome environmental stresses

Motoyuki Ashikari, Jian Feng Ma

RICE 8 ( 1 ) 10 2015.2

A small RNA mediated regulation of a stress-activated retrotransposon and the tissue specific transposition during the reproductive period in Arabidopsis

Wataru Matsunaga, Naohiko Ohama, Noriaki Tanabe, Yukari Masuta, Seiji Masuda, Namiki Mitani, Kazuko Yamaguchi-Shinozaki, Jian F. Ma, Atsushi Kato, Hidetaka Ito

FRONTIERS IN PLANT SCIENCE 6 ( FEB ) 48 2015.2

Language：English Publishing type：Research paper (scientific journal) Publisher：FRONTIERS RESEARCH FOUNDATION

Transposable elements (TEs) are key elements that facilitate genome evolution of the host organism. A number of studies have assessed the functions of TEs, which change gene expression in the host genome. Activation of TEs is controlled by epigenetic modifications such as DNA methylation and histone modifications. Several recent studies have reported that TEs can also be activated by biotic or abiotic stress in some plants. We focused on a Ty1/copia retrotransposon, ONSEN, that is activated by heat stress (HS) in Arabidopsis. We found that transcriptional activation of ONSEN was regulated by a small interfering RNA (siRNA)-related pathway, and the activation could also be induced by oxidative stress. Mutants deficient in siRNA biogenesis that were exposed to HS at the initial stages of vegetative growth showed transgenerational transposition. The transposition was also detected in the progeny, which originated from tissue that had differentiated after exposure to the HS. The results indicated that in some undifferentiated cells, transpositional activity could be maintained quite long after exposure to the HS.

DOI： 10.3389/fpls.2015.00048

Foreword

Jian Feng Ma

Silicon and Plant Diseases v - vi 2015.1

Physiological characterization of aluminum tolerance and accumulation in tartary and wild buckwheat

Hua Wang, Rong Fu Chen, Takashi Iwashita, Ren Fang Shen, Jian Feng Ma

NEW PHYTOLOGIST 205 ( 1 ) 273 - 279 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

Ionic aluminum (Al) is toxic for plant growth, but some plant species are able to accumulate Al at high concentrations without showing toxicity symptoms. In order to determine whether other species in the genus Fagopyrum are able to accumulate Al like common buckwheat (Fagopyrum esculentum), we investigated the external and internal detoxification mechanisms of Al in two self-compatible species: tartary (Fagopyrum tataricum) and wild buckwheat (Fagopyrum homotropicum). Both tartary and wild buckwheat showed high Al tolerance comparable to common buckwheat. Furthermore, these two species also secreted oxalate rapidly from the roots in response to Al in a time-dependent manner. Both tartary and wild buckwheat accumulated >1mgg(-1) Al in the leaves after short-term exposure to Al. Analysis with Al-27-nuclear magnetic resonance (NMR) revealed that Al was present in the form of Al-oxalate (1:3 ratio) in the roots and leaves, but in the form of Al-citrate (1:1 ratio) in the xylem sap in both species. These results indicate that similar to common buckwheat, both tartary and wild buckwheat detoxify Al externally and internally, respectively, by secreting oxalate from the roots and by forming the Al-oxalate complex, which is a nonphytotoxic form. These features of Al response and accumulation may be conserved in genus Fagopyrum.

DOI： 10.1111/nph.13011

AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis

Takaaki Miyaji, Takashi Kuromori, Yu Takeuchi, Naoki Yamaji, Kengo Yokosho, Atsushi Shimazawa, Eriko Sugimoto, Hiroshi Omote, Jian Feng Ma, Kazuo Shinozaki, Yoshinori Moriyama

NATURE COMMUNICATIONS 6 5928 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Ascorbate is an antioxidant and coenzyme for various metabolic reactions in vivo. In plant chloroplasts, high ascorbate levels are required to overcome photoinhibition caused by strong light. However, ascorbate is synthesized in the mitochondria and the molecular mechanisms underlying ascorbate transport into chloroplasts are unknown. Here we show that AtPHT4;4, a member of the phosphate transporter 4 family of Arabidopsis thaliana, functions as an ascorbate transporter. In vitro analysis shows that proteoliposomes containing the purified AtPHT4; 4 protein exhibit membrane potential- and Cl- dependent ascorbate uptake. The AtPHT4; 4 protein is abundantly expressed in the chloroplast envelope membrane. Knockout of AtPHT4; 4 results in decreased levels of the reduced form of ascorbate in the leaves and the heat dissipation process of excessive energy during photosynthesis is compromised. Taken together, these observations indicate that the AtPHT4; 4 protein is an ascorbate transporter at the chloroplast envelope membrane, which may be required for tolerance to strong light stress.

DOI： 10.1038/ncomms6928

Integrated research for crop improvement based on the molecular physiological strategies to global environmental changes

Saisho Daisuke, Horie Tomoaki, Kinoshita Toshinori, Feng Ma Jian

Breeding Research 17 ( 2 ) 71 - 76 2015

Transcriptional activity and silencing of heat activated retrotransposon in Arabidopsis

Wataru Matsunaga, Yukari Masuta, Namiki Mitani, Ma Jian Feng, Atsushi Kato, Hidetaka Ito

GENES & GENETIC SYSTEMS 89 ( 6 ) 316 - 316 2014.12

Global Transcriptome Analysis of Al-Induced Genes in an Al-Accumulating Species, Common Buckwheat (Fagopyrum esculentum Moench)

Kengo Yokosho, Naoki Yamaji, Jian Feng Ma

PLANT AND CELL PHYSIOLOGY 55 ( 12 ) 2077 - 2091 2014.12

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Buckwheat (Fagopyrum esculentum Moench) is a species with high aluminum (Al) tolerance and accumulation. Although the physiological mechanisms for external and internal detoxification of Al have been well studied, the molecular mechanisms responsible are poorly understood. Here, we conducted a genome-wide transcriptome analysis of Al-responsive genes in the roots and leaves using RNA sequencing (RNA-Seq) technology. RNA-Seq generated reads ranging from 56 x 10(6) to 93 x 10(6). A total of 148,734 transcript contigs with an average length of 1,014 bp were assembled, generating 84,516 unigenes. Among them, 31,730 and 23,853 unigenes were annotated, respectively, in the NCBI plant database and TAIR database for Arabidopsis. Of the annotated genes, 4,067 genes in the roots and 2,663 genes in the leaves were up-regulated (>2-fold) by Al exposure, while 2,456 genes in the roots and 2,426 genes in the leaves were down-regulated (<2-fold) A few STOP1/ART1 (SENSITIVE TO PROTON RHIZOTOXICITY1/AL RESISTANCE TRANSCRIPTION FACTOR1)-regulated gene homologs including FeSTAR1, FeALS3 (ALUMINUM SENSITIVE3), FeALS1 (ALUMINUM SENSITIVE1), FeMATE1 and FeMATE2 (MULTIDRUG AND TOXIC COMPOUND EXTRUSION1 and 2) were also up-regulated in buckwheat, indicating some common Al tolerance mechanism across the species, although most STOP1/ART1-regulated gene homologs were not changed. Most genes involved in citric and oxalic acid biosynthesis were not significantly altered. Some transporter genes were highly expressed in the roots and leaves and responded to Al stress, implicating their role in Al tolerance and accumulation. Overall, our data provide a platform for further characterizing the functions of genes involved in Al tolerance and accumulation in buckwheat.

DOI： 10.1093/pcp/pcu135

A rice ABC transporter, OsABCC1, reduces arsenic accumulation in the grain

Won-Yong Song, Tomohiro Yamaki, Naoki Yamaji, Donghwi Ko, Ki-Hong Jung, Miho Fujii-Kashino, Gynheung An, Enrico Martinoia, Youngsook Lee, Jian Feng Ma

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 111 ( 44 ) 15699 - 15704 2014.11

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL ACAD SCIENCES

Arsenic (As) is a chronic poison that causes severe skin lesions and cancer. Rice (Oryza sativa L.) is a major dietary source of As; therefore, reducing As accumulation in the rice grain and thereby diminishing the amount of As that enters the food chain is of critical importance. Here, we report that a member of the Oryza sativa C-type ATP-binding cassette (ABC) transporter (OsABCC) family, OsABCC1, is involved in the detoxification and reduction of As in rice grains. We found that OsABCC1 was expressed in many organs, including the roots, leaves, nodes, peduncle, and rachis. Expression was not affected when plants were exposed to low levels of As but was up-regulated in response to high levels of As. In both the basal nodes and upper nodes, which are connected to the panicle, OsABCC1 was localized to the phloem region of vascular bundles. Furthermore, OsABCC1 was localized to the tonoplast and conferred phytochelatin-dependent As resistance in yeast. Knockout of OsABCC1 in rice resulted in decreased tolerance to As, but did not affect cadmium toxicity. At the reproductive growth stage, the As content was higher in the nodes and in other tissues of wild-type rice than in those of OsABCC1 knockout mutants, but was significantly lower in the grain. Taken together, our results indicate that OsABCC1 limits As transport to the grains by sequestering As in the vacuoles of the phloem companion cells of the nodes in rice.

DOI： 10.1073/pnas.1414968111

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