Faculty Profiles - MA Jian Feng

Papers - MA Jian Feng

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Zinc Transport in Rice: Dilemma between optimal plant requirement and human nutrition. International journal

Sheng Huang, Naoki Yamaji, Jian Feng Ma

Journal of experimental botany 73 ( 6 ) 1800 - 1808 2021.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press ({OUP})

Zinc (Zn) is an essential micronutrient for both plants and animals, while Zn deficiency in crops and humans is a global problem affecting crop productivity and human health. Since plants and humans differ in their Zn requirement, there is a dilemma between plant nutrition and human nutrition. In this review, we focus on the transport system of Zn from soil to grain in rice (Oryza sativa), which is a major dietary source of Zn for people subsiding on rice-based diets. We describe transporters belonging to different family, which are involved in the uptake, vacuolar sequestration, root-to-shoot translocation and distribution of Zn. We also discuss the possible regulation mechanism of these transporters. Several examples are given on enhancing Zn accumulation and bioavailability in rice grains through manipulation of genes highly expressed in the nodes, where Zn is highly deposited. We finally provide our perspectives toward breeding rice cultivars with both increased tolerance to Zn-deficiency stress and high Zn density in rice grains.

DOI： 10.1093/jxb/erab478

Lateral roots but not root hairs contribute to high uptake of manganese and cadmium in rice. International journal

En Yu, Naoki Yamaji, Chuanzao Mao, Hua Wang, Jian Feng Ma

Journal of experimental botany 72 ( 20 ) 7219 - 7228 2021.10

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

Rice (Oryza sativa L.) can accumulate high manganese (Mn) in the shoots through uptake by the roots, which consist of crown roots, lateral roots and root hairs. We investigated the role of lateral roots and root hairs in Mn and cadmium (Cd) uptake by using two indica rice mutants defective in formation of lateral roots (osiaa11) and root hairs (osrhl1). The uptake of Mn and Cd in osiaa11 was significantly lower than that in wild type 'Kasalath', but there was no difference between wild type and osrhl1. Furthermore, a kinetic study showed that Mn uptake in osiaa11 was much lower than that in wild type and osrhl1 across a wide range of Mn concentrations. The role of lateral roots in Mn and Cd uptake was further confirmed in a japonica rice mutant defective in lateral root formation. We found that expression of Mn transporter gene Natural Resistance-Associated Macrophage Protein 5 (OsNRAMP5), but not of Metal Tolerance Protein 9 (OsMTP9), was lower in osiaa11 than in wild type; however, there were no differences between osrhl1 and the wild type. Immunostaining showed that OsNRAMP5 and OsMTP9 were localized in the exodermis and endodermis of crown roots and lateral roots, but not in the root hairs. Taken together, our results indicate that lateral roots, but not root hairs, play an important role in high Mn and Cd uptake in rice.

DOI： 10.1093/jxb/erab329

Transport Systems of Mineral Elements in Plants: Transporters, Regulation and Utilization

Jian Feng Ma, Yi-Fang Tsay

Plant and Cell Physiology 62 ( 4 ) 539 - 540 2021.9

Germplasm evaluation for crop improvement: Analysis of grain quality and cadmium accumulation in barley

Kazuhiro Sato, Kazuyoshi Takeda, Jian Feng Ma

Journal of Cereal Science 101 103297 - 103297 2021.9

Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV}

Evaluating genetic variation in barley (Hordeum vulgare) germplasm, combined with genome-wide genotyping, is vital for identifying genes controlling important grain-quality traits. For example, in addition to traditional grain quality properties such as starch and protein contents, grain safety parameters such as heavy metal content, are important in the use of barley for human food and animal feed. A number of genes affecting grain quality have been identified by map-based cloning strategies and functionally analyzed by genetic transformation experiments. Moreover, germplasm evaluation yielded information that enabled the introgression of a key gene controlling grain cadmium accumulation into an elite barley cultivar, reducing the content of this heavy metal in grain. Genotyping of molecular markers and resequencing of germplasm accessions may provide information about how grain quality–related loci evolved and how the current allelic diversity was established. In this review, we describe germplasm resources for barley grain quality–related traits and the methods used to analyze the functions of genes controlling these traits, illustrating cadmium accumulation as an example. We also discuss future directions for the efficient identification of grain quality–related genes.

DOI： 10.1016/j.jcs.2021.103297

Role of qGZn9a in controlling grain zinc concentration in rice, Oryza sativa L.

Miki Ogasawara, Naoya Miyazaki, Gotaro Monden, Kenta Taniko, Sathya Lim, Masahide Iwata, Takashige Ishii, Jian Feng Ma, Ryo Ishikawa

Theoretical and Applied Genetics 134 ( 9 ) 3013 - 3022 2021.9

Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media {LLC}

Key message: A candidate gene responsible for higher grain zinc accumulation in rice was identified, which was probably associated with a partial defect in anther dehiscence. Abstract: Zinc (Zn) is an essential mineral element in many organisms. Zn deficiency in humans causes various health problems; therefore, an adequate dietary Zn intake is required daily. Rice, Oryza sativa, is one of the main crops cultivated in Asian countries, and one of the breeding scopes of rice is to increase the grain Zn levels. Previously, we found that an Australian wild rice strain, O. meridionalis W1627, exhibits higher grain Zn levels than cultivated rice, O. sativa Nipponbare, and identified responsible genomic loci. An increase in grain Zn levels caused by one of the loci, qGZn9a, is associated with fertility reduction, but how this negative effect on grain productivity is regulated remains unknown. In this study, we artificially trimmed spikelets on the flowering day and found that a reduction in number of seeds was associated with an increase in the grain Zn levels. We also found that a partial defect in anther dehiscence correlated with the increase in grain Zn levels in plants carrying the W1627 chromosomal segment at qGZn9a in a Nipponbare genetic background. Among eight candidate genes in the qGZn9a region, three were absent from the corresponding region of W1627; one of these, Os09g0384900, encoding a DUF295 protein with an unknown function, was found to be specifically expressed in the developing anther, thereby suggesting that the gene may be involved in the regulation of anther dehiscence. As fertility and grain Zn levels are essential agronomic traits in rice, our results highlight the importance of balancing these two traits.

DOI： 10.1007/s00122-021-03873-4

Three polarly localized ammonium transporter 1 members are cooperatively responsible for ammonium uptake in rice under low ammonium condition

Noriyuki Konishi, Jian Feng Ma

New Phytologist 232 ( 4 ) 1778 - 1792 2021.8

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

Ammonium is a preferential nitrogen form for rice (Oryza sativa) grown in paddy field, but the molecular mechanisms for ammonium uptake have not been well understood. We functionally characterized three members belonging to ammonium transporter 1 (AMT1) and investigated their contributions to ammonium uptake. Spatial expression analysis showed that the upregulated expression of OsAMT1;1 and OsAMT1;2 and downregulated expression of OsAMT1;3 by ammonium were higher in the root mature region than in the root tips. All OsAMT1 members were polarly localized at the distal side of exodermis in the mature region of crown roots and lateral roots. Upon exposure to ammonium, localization of OsAMT1;1 and OsAMT1;2 was also observed in the endoplasmic reticulum, but their abundance in the plasma membrane was not changed. Single knockout of either gene did not affect ammonium uptake, but knockout of all three genes resulted in 95% reduction of ammonium uptake. However, the nitrogen uptake did not differ between the wild-type rice and triple mutants at high ammonium and nitrate supply. Our results indicate that three OsAMT1 members are cooperatively required for uptake of low ammonium in rice roots and that they undergo a distinct regulatory mechanism in response to ammonium.

DOI： 10.1111/nph.17679

LYSINE KETOGLUTARATE REDUCTASE TRANS-SPLICING RELATED 1 is involved in temperature-dependent root growth in rice

En Yu, Naoki Yamaji, Keiich Mochida, Ivan Galis, Kanatani Asaka, Jian Feng Ma, Hideki Takahashi

Journal of Experimental Botany 72 ( 18 ) 6336 - 6349 2021.5

Publishing type：Research paper (scientific journal) Publisher：Oxford University Press ({OUP})

Root length is an important root parameter directly related to the uptake of water and nutrients. However, the molecular mechanisms controlling root length are still not fully understood. Here, we isolated a short-root mutant of rice, dice2 (defective in cell elongation 2). The cell length and meristem size of the roots were decreased in dice2, but the root function in terms of mineral element uptake, root cell width, and root anatomy were hardly altered compared with wild-type (WT) rice. The root growth defect in dice2 could be partially rescued by high temperature. Map-based cloning combined with a complementation test revealed that the short-root phenotype was caused by a nonsense mutation in a gene which was annotated to encode Lysine Ketoglutarate Reductase Trans-Splicing related 1 (OsLKRT1). OsLKRT1, encoding a cytosol-localized protein, was expressed in all cells of the root tip and elongation region as well as the shoot. RNA-seq analysis showed that there was no difference between dice2 and the WT in the expression level of genes involved in root development identified so far. These results indicate that OsLKRT1 is involved in a novel pathway required for root cell elongation in rice, although its exact role remains to be further investigated.

DOI： 10.1093/jxb/erab240

ANAC044 is associated with P reutilization in P deficient Arabidopsis thaliana root cell wall in an ethylene dependent manner

Xiao Long Zhang, Qi Wu, Ye Tao, Xiao Fang Zhu, Naoki Takahashi, Masaaki Umeda, Ren Fang Shen, Jian Feng Ma

Environmental and Experimental Botany 185 104386 - 104386 2021.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV}

Phosphorus (P) deficiency is a major problem in agriculture, thus identifying mechanisms affecting plant's ability to reutilize previously assimilated P is a prerequisite for improving the P homeostasis in crops grown with P deficient soil. Here, we reported the involvement of a NAC (No apical meristem [NAM], Arabidopsis transcription activation factor [ATAF] and Cup-shaped cotyledon [CUC]) transcription factor in response to P deficiency. Compared to the wild type (WT, Col-0) and two independent complementary lines, the anac044 mutant displayed P deficiency resistant phenotype, together with the increased root length, root and shoot biomass under P deficiency. In addition, ANAC044 was highly expressed in root and silique. Upon P deficient treatment even within 1 d, ANAC044 transcript accumulation was strongly up-regulated. Further analysis revealed that, under P-deficient condition, the cell wall, particularly the pectin of anac044, released more P than that of WT and complementary lines, accompanied by an increment of ethylene production, as a result, more soluble and total P were available in anac044 root and shoot. Thus, the study here uncovers the role of ANAC044-regulated cell wall P remobilization through ethylene signaling under P deficiency.

DOI： 10.1016/j.envexpbot.2021.104386

Role of a vacuolar iron transporter OsVIT2 in the distribution of iron to rice grains

Jing Che, Naoki Yamaji, Jian Feng Ma

New Phytologist 230 ( 3 ) 1049 - 1062 2021.5

Publishing type：Research paper (scientific journal) Publisher：Wiley

Iron (Fe) from rice grains is an important source of dietary intake; however, the molecular mechanisms responsible for loading of Fe to the grains are poorly understood. We functionally characterized a vacuolar iron transporter gene, OsVIT2 in terms of expression pattern, cellular localization, and mutant phenotypes. OsVIT2 was expressed in the parenchyma cell bridges of nodes, in the mestome sheath of leaf sheath and aleurone of the caryopsis. Mutation of OsVIT2 resulted in decreased Fe distribution to the leaf sheath, nodes, and aleurone, but increased Fe to the leaf blade and grains. Furthermore, Fe was heavily deposited in the parenchyma cell bridges, mestome sheath and aleurone in the wild-type rice, but this accumulation was decreased in the knockout lines. Conversely, heavier deposition of Fe was observed in the embryo and endosperm of the grains of knockout lines compared with the wild-type rice, resulting in increased Fe accumulation in the polished rice without yield penalty. These results indicate that OsVIT2 is involved in the distribution of Fe to the grains through sequestering Fe into vacuoles in mestome sheath, nodes, and aleurone layer and that knockout of this gene provides a potential way for Fe biofortification without yield penalty.

DOI： 10.1111/nph.17219

Expression Level of Transcription Factor ART1 Is Responsible for Differential Aluminum Tolerance in Indica Rice

Li Ming Sun, Jing Che, Jian Feng Ma, Ren Fang Shen

PLANTS-BASEL 10 ( 4 ) 2021.4

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

Rice is the most aluminum (Al)-tolerant species among the small grain cereals, but there are great variations in the Al tolerance between subspecies, with higher tolerance in japonica subspecies than indica subspecies. Here, we performed a screening of Al tolerance using 65 indica cultivars and found that there was also a large genotypic difference in Al tolerance among indica subspecies. Further characterization of two cultivars contrasting in Al tolerance showed that the expression level of ART1 (ALUMINUM RESISTANCE TRANSCRIPTION FACTOR 1) encoding a C2H2-type Zn-finger transcription factor, was higher in an Al-tolerant indica cultivar, Jinguoyin, than in an Al-sensitive indica cultivar, Kasalath. Furthermore, a dose-response experiment showed that ART1 expression was not induced by Al in both cultivars, but Jinguoyin always showed 5.9 to 11.4-fold higher expression compared with Kasalath, irrespectively of Al concentrations. Among genes regulated by ART1, 19 genes showed higher expression in Jinguoyin than in Kasalath. This is associated with less Al accumulation in the root tip cell wall in Jinguoyin. Sequence comparison of the 2-kb promoter region of ART1 revealed the extensive sequence polymorphism between two cultivars. Whole transcriptome analysis with RNA-seq revealed that more genes were up- and downregulated by Al in Kasalath than in Jinguoyin. Taken together, our results suggest that there is a large genotypic variation in Al tolerance in indica rice and that the different expression level of ART1 is responsible for the genotypic difference in the Al tolerance.

DOI： 10.3390/plants10040634

Fine regulation system for distribution of boron to different tissues in rice

Ji Feng Shao, Naoki Yamaji, Sheng Huang, Jian Feng Ma

NEW PHYTOLOGIST 230 ( 2 ) 656 - 668 2021.2

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

Boron (B) is essential for growth and development, with the B requirement differing depending on the particular organs and tissues, but the molecular mechanisms underlying the preferential distribution of B to different tissues are poorly understood.We investigated the role of a rice gene (OsBOR1) encoding a B efflux transporter in the distribution of B to different tissues under different B supplies.OsBOR1 was highly expressed in the nodes at all growth stages. The OsBOR1 protein shows polar localization at the distal side of bundle sheath cells in nodes and xylem parenchyma cells of elongating leaf sheath, but in the mature leaf sheath and blade at the proximal side of bundle sheath cells. Furthermore, the expression of OsBOR1 was not affected by external B fluctuations, but the OsBOR1 protein was gradually degraded in response to high B. Knockout of this gene altered B distribution, decreasing the distribution of B to new leaves and panicles but increasing B distribution to old leaves.These results indicate that OsBOR1 expressed in nodes and leaf sheath is involved in the preferential distribution of B to different tissues in rice. Furthermore, the OsBOR1 undergoes degradation in response to high B for fine regulation of B distribution to different tissues.

DOI： 10.1111/nph.17169

A transporter for delivering zinc to the developing tiller bud and panicle in rice

Shuai Mu, Naoki Yamaji, Akimasa Sasaki, Le Luo, Binbin Du, Jing Che, Huichao Shi, Haoqiang Zhao, Sheng Huang, Fenglin Deng, Zhenguo Shen, Mary Lou Guerinot, Luqing Zheng, Jian Feng Ma

Plant Journal 105 ( 3 ) 786 - 799 2021.2

Publishing type：Research paper (scientific journal)

Tiller number is one of the most important agronomic traits that determine rice (Oryza sativa) yield. Active growth of tiller bud (TB) requires high amount of mineral nutrients; however, the mechanism underlying the distribution of mineral nutrients to TB with low transpiration is unknown. Here, we found that the distribution of Zn to TB is mediated by OsZIP4, one of the ZIP (ZRT, IRT-like protein) family members. The expression of OsZIP4 was highly detected in TB and nodes, and was induced by Zn deficiency. Immunostaining analysis revealed that OsZIP4 was mainly expressed in phloem of diffuse vascular bundles in the nodes and the axillary meristem. The mutation of OsZIP4 did not affect the total Zn uptake, but altered Zn distribution; less Zn was delivered to TB and new leaf, but more Zn was retained in the basal stems at the vegetative growth stage. Bioimaging analysis showed that the mutant aberrantly accumulated Zn in enlarged and transit vascular bundles of the basal node, whereas in wild-type high accumulation of Zn was observed in the meristem part. At the reproductive stage, mutation of OsZIP4 resulted in delayed panicle development, which is associated with decreased Zn distribution to the panicles. Collectively, OsZIP4 is involved in transporting Zn to the phloem of diffuse vascular bundles in the nodes for subsequent distribution to TBs and other developing tissues. It also plays a role in transporting Zn to meristem cells in the TBs.

DOI： 10.1111/tpj.15073

Transport of cadmium from soil to grain in cereal crops: A review

Jian Feng MA, Ren Fang SHEN, Ji Feng SHAO

Pedosphere 31 ( 1 ) 3 - 10 2021.2

Publishing type：Research paper (scientific journal)

Due to rapid urbanization and industrialization, many soils for crop production are contaminated by cadmium (Cd), a heavy metal highly toxic to many organisms. Cereal crops such as rice, wheat, maize, and barley are the primary dietary source of Cd for humans, and reducing Cd transfer from soil to their grains is therefore an important issue for food safety. During the last decade, great progress has been made in elucidating the molecular mechanisms of Cd transport, particularly in rice. Inter- and intraspecific variations in Cd accumulation have been observed in cereal crops. Transporters for Cd have been identified in rice and other cereal crops using genotypic differences in Cd accumulation and mutant approaches. These transporters belong to different transporter families and are involved in the uptake, vacuolar sequestration, root-to-shoot translocation, and distribution of Cd. Attempts have been made to reduce Cd accumulation in grains by manipulating these transporters through overexpression or knockout of the transporter genes, as well as through marker-assisted selection breeding based on genotypic differences in Cd accumulation in the grains. In this review, we describe recent progress on molecular mechanisms of Cd accumulation in cereal crops and compare different molecular strategies for minimizing Cd accumulation in grains.

DOI： 10.1016/S1002-0160(20)60015-7

Cadmium transfer in contaminated soil-rice systems: Insights from solid-state speciation analysis and stable isotope fractionation

Matthias Wiggenhauser, Anne Marie Aucour, Sarah Bureau, Sylvain Campillo, Philippe Telouk, Marco Romani, Jian Feng Ma, Gautier Landrot, Géraldine Sarret

Environmental Pollution 269 2021.1

Publishing type：Research paper (scientific journal)

Initial Cadmium (Cd) isotope fractionation studies in cereals ascribed the retention of Cd and its light isotopes to the binding of Cd to sulfur (S). To better understand the relation of Cd binding to S and Cd isotope fractionation in soils and plants, we combined isotope and XAS speciation analyses in soil-rice systems that were rich in Cd and S. The systems included distinct water management (flooded vs. non-flooded) and rice accessions with (excluder) and without (non-excluder) functional membrane transporter OsHMA3 that transports Cd into root vacuoles. Initially, 13% of Cd in the soil was bound to S. Through soil flooding, the proportion of Cd bound to S increased to 100%. Soil flooding enriched the rice plants towards heavy isotopes (δ114/110Cd = −0.37 to −0.39%) compared to the plants that grew on non-flooded soils (δ114/110Cd = −0.45 to −0.56%) suggesting that preferentially light Cd isotopes precipitated into Cd sulfides. Isotope compositions in CaCl2 root extracts indicated that the root surface contributed to the isotope shift between soil and plant during soil flooding. In rice roots, Cd was fully bound to S in all treatments. The roots in the excluder rice strongly retained Cd and its lights isotopes while heavy isotopes were transported to the shoots (Δ114/110Cdshoot-root 0.16–0.19‰). The non-excluder rice accumulated Cd in shoots and the apparent difference in isotope composition between roots and shoots was smaller than that of the excluder rice (Δ114/110Cdshoot-root −0.02 to 0.08‰). We ascribe the retention of light Cd isotopes in the roots of the excluder rice to the membrane transport of Cd by OsHMA3 and/or chelating Cd–S complexes in the vacuole. Cd–S was the major binding form in flooded soils and rice roots and partly contributed to the immobilization of Cd and its light isotopes in soil-rice systems.

DOI： 10.1016/j.envpol.2020.115934

Jian Feng Ma

Jian Feng Ma

NEW PHYTOLOGIST 229 ( 2 ) 673 - 674 2021.1

Two metallothionein genes highly expressed in rice nodes are involved in distribution of Zn to the grain

Gui Jie Lei, Naoki Yamaji, Jian Feng Ma

NEW PHYTOLOGIST 229 ( 2 ) 1007 - 1020 2021.1

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

A rice node is a hub for distribution of mineral elements; however, most genes highly expressed in the node have not been functionally characterized. Transcriptomic analysis of a rice node revealed that two metallothionein genes,OsMT2bandOsMT2c, were highly expressed in the node I. We functionally characterized these genes in terms of gene expression pattern, cellular and subcellular localization, phenotypic analysis of the single and double knockout mutants and metal-binding ability. BothOsMT2bandOsMT2cwere mainly and constitutively expressed in the phloem region of enlarged and diffuse vascular bundles in the nodes and of the anther. Knockout of eitherOsMT2borOsMT2cincreased zinc (Zn) accumulation in the nodes, but decreased Zn distribution to the panicle, resulting in decreased grain yield. A double mutant,osmt2bmt2c, showed further negative effects on the Zn distribution and grain yield. By contrast, knockout ofOsMT2bhad a small effect on copper (Cu) accumulation. Both OsMT2b and OsMT2c showed binding ability with Zn, whereas only OsMT2b showed binding ability with Cu in yeast. Our results suggest that bothOsMT2bandOsMT2cplay an important role mainly in the distribution of Zn to grain through chelation and subsequent transport of Zn in the phloem in rice.

DOI： 10.1111/nph.16860

Linking transport system of silicon with its accumulation in different plant species

Namiki Mitani-Ueno, Jian Feng Ma

Soil Science and Plant Nutrition 67 ( 1 ) 10 - 17 2021

Silicon (Si) is a beneficial element for plants, which helps to mitigate various biotic and abiotic stresses. Since the last review on Si published in this journal in 2004, great progress has been made in understanding transport system of Si in different plant species. The discovery of two different transporters for Si (Lsi1 and Lsi2) in rice led to intensive investigation of Si transporters in other plant species. Lsi1 belongs to the Nodulin 26-like intrinsic proteins (NIPs) subfamily in the aquaporin (AQP) family and functions as an influx transporter for Si. By contrast, Lsi2 belongs to the anion transporter superfamily and functions as an efflux transporter of Si. They are polarly localized at the distal and proximal sides, respectively, of both exodermis and endodermis of rice roots and are required for efficient uptake of Si. So far, homologs of Lsi1 and Lsi2 are identified not only in monocots, but also in dicots, which greatly differ in Si accumulation in the aboveground parts. However, the expression pattern, cell-type-specific expression, and polar localization of these transporters differ with plant species. In this review, we focus on recent progress in Si transporters identified in different plant species. We link these transporters with an accumulation of Si in different plant species in terms of expression pattern, cell-type-specific expression, polar localization of these transporters and propose three uptake systems of Si in different plant species. We also provide the perspectives toward a better understanding of Si transport system in different plant species and discuss its essentiality for plant growth.

DOI： 10.1080/00380768.2020.1845972

Buckwheat FeNramp5 Mediates High Manganese Uptake in Roots

Kengo Yokosho, Naoki Yamaji, Jian Feng Ma

Plant and Cell Physiology 62 ( 4 ) 600 - 609 2020.12

Publishing type：Research paper (scientific journal) Publisher：Oxford University Press ({OUP})

Manganese (Mn) is an essential element for plant growth and development, but transporters required for Mn uptake have only been identified in a few plant species. Here, we functionally characterized a member of the natural resistance-associated macrophage proteins (Nramps) family, FeNramp5 in buckwheat (Fagopyrum esculentum Moench), which is known as a species well adapted to acidic soils. FeNramp5 was mainly expressed in the roots, and its expression was upregulated by the deficiency of Mn and Fe. Furthermore, spatial and tissue-specific expression analysis showed that FeNramp5 was expressed in all tissues of the basal root regions. FeNramp5-GFP protein was localized to the plasma membrane when transiently expressed in buckwheat leaf protoplast. FeNramp5 showed the transport activity for Mn2+ and Cd2+ but not for Fe2+ when expressed in yeast. Furthermore, the transport activity for Mn2+ was higher in yeast expressing FeNramp5 than in yeast expressing AtNramp1. FeNramp5 was also able to complement the phenotype of Arabidopsis atnramp1 mutant in terms of the growth and accumulation of Mn and Cd. The absolute expression level of AtNramp1 was comparable to that of FeNramp5 in the roots, but buckwheat accumulated higher Mn than Arabidopsis when grown under the same condition. Further analysis showed that at least motif B in FeNramp5 seems important for its high transport activity for Mn. These results indicate that FeNramp5 is a transporter for the uptake of Mn and Cd and its higher transport activity for Mn is probably associated with higher Mn accumulation in buckwheat.

DOI： 10.1093/pcp/pcaa153

Silicon suppresses zinc uptake through down-regulating zinc transporter gene in rice

Sheng Huang, Jian Feng Ma

PHYSIOLOGIA PLANTARUM 170 ( 4 ) 580 - 591 2020.12

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

One of the beneficial effects of silicon (Si) is to improve nutrient imbalance including deficiency and excess of nutrients, however the molecular mechanisms underlying this effect are still poorly understood. In this study, we investigated the interaction between Si and zinc (Zn) in rice by using a mutant (lsi1) defective in Si uptake and its wild-type (WT, cv. Oochikara) at different Zn levels. High Zn inhibited the root elongation of both WT andlsi1mutant, but Si did not alleviate this inhibition in both lines. By contrast, Si supply decreased Zn concentration in both the roots and shoots of the WT, but not in thelsi1mutant. A short-term (24 h) labeling experiment with stable isotope(67)Zn showed that Si decreased(67)Zn uptake, but did not affect the root-to-shoot translocation and distribution ratio to different organs of(67)Zn in the WT. Furthermore, Si accumulated in the shoots, rather than Si in the external solution, is required for suppressing Zn uptake, but this was not caused by Si-decreased transpiration. A kinetic study showed that Si did not affect K(m)value of root Zn uptake, but decreased V(max)value in the WT. Analysis of genes related with Zn transport showed that among ZIP family genes, the expression of onlyOsZIP1implicated in Zn uptake, was down-regulated by Si in the WT, but not in thelsi1mutant. These results indicate that Si accumulated in the shoots suppresses the Zn uptake through down-regulating the transporter gene involved in Zn uptake in rice.

DOI： 10.1111/ppl.13196

The grapevine NIP2;1 aquaporin is a silicon channel

Henrique Noronha, Angelica Silva, Namiki Mitani-Ueno, Carlos Conde, Farzana Sabir, Catarina Prista, Graca Soveral, Paul Isenring, Jian Feng Ma, Richard R. Belanger, Hernani Geros

JOURNAL OF EXPERIMENTAL BOTANY 71 ( 21 ) 6789 - 6798 2020.12

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

Silicon (Si) supplementation has been shown to improve plant tolerance to different stresses, and its accumulation in the aerial organs is mediated by NIP2;1 aquaporins (Lsi channels) and Lsi2-type exporters in roots. In the present study, we tested the hypothesis that grapevine expresses a functional NIP2;1 that accounts for root Si uptake and, eventually, Si accumulation in leaves. Own-rooted grapevine cuttings of the cultivar Vinhao accumulated >0.2% Si (DW) in leaves when irrigated with 1.5 mM Si for 1 month, while Si was undetected in control leaves. Real-time PCR showed that VvNIP2;1 was highly expressed in roots and in green berries. The transient transformation of tobacco leaf epidermal cells mediated by Agrobacterium tumefaciens confirmed VvNIP2;1 localization at the plasma membrane. Transport experiments in oocytes showed that VvNIP2;1 mediates Si and arsenite uptake, whereas permeability studies revealed that VvNIP2;1 expressed in yeast is unable to transport water and glycerol. Si supplementation to pigmented grape cultured cells (cv. Gamay Freaux) had no impact on the total phenolic and anthocyanin content, or on the growth rate and VvNIP2;1 expression. Long-term experiments should help determine the extent of Si uptake over time and whether grapevine can benefit from Si fertilization.

DOI： 10.1093/jxb/eraa294

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