Oxford University PressActa Medica Okayama0022-095770102019The tonoplast-localized transporter OsHMA3 plays an important role in maintaining Zn homeostasis in rice27172725ENHongmeiCaiInstitute of Plant Science and Resources, Okayama UniversityShengHuangInstitute of Plant Science and Resources, Okayama UniversityJingCheInstitute of Plant Science and Resources, Okayama UniversityNaokiYamajiInstitute of Plant Science and Resources, Okayama UniversityJian FengMaInstitute of Plant Science and Resources, Okayama UniversityIn order to respond to fluctuating zinc (Zn) in the environment, plants must have a system to control Zn homeostasis. However, how plants maintain an appropriate level of Zn during their growth and development is still poorly understood. In this study, we found that OsHMA3, a tonoplast-localized transporter for Zn/Cd, plays an important role in Zn homeostasis in rice. Accessions with the functional allele of OsHMA3 showed greater tolerance to high Zn than those with the non-functional allele based on root elongation test. A 67Zn-labeling experiment showed that accessions with loss of function of OsHMA3 had lower Zn accumulation in the roots but similar concentrations in the shoots compared with functional OsHMA3 accessions. When exposed to Zn-free growing medium, the concentration in the root cell sap was rapidly decreased in accessions with functional OsHMA3, but less dramatic changes were observed in non-functional accessions. A mobility experiment showed that more Zn in the roots was translocated to the shoots in accessions with functional OsHMA3. Higher expression levels of OsZIP4, OsZIP5, OsZIP8, and OsZIP10 were found in the roots of accessions with functional OsHMA3 in response to Zn deficiency. Taken together, our results indicate that OsHMA3 plays an important role in rice roots in both Zn detoxification and storage by sequestration into the vacuoles, depending on Zn concentration in the environment.No potential conflict of interest relevant to this article was reported.WileyActa Medica Okayama0140-779145112022FE UPTAKE]INDUCING PEPTIDE1 maintains Fe translocation by controlling Fe deficiency response genes in the vascular tissue of Arabidopsis33223337ENSatoshiOkadaGroup of Environmental Stress Response Systems, Institute of Plant Science and Resources, Okayama UniversityGui J.LeiGroup of Plant Stress Physiology, Institute of Plant Science and Resources, Okayama UniversityNaokiYamajiGroup of Plant Stress Physiology, Institute of Plant Science and Resources, Okayama UniversityShengHuangGroup of Plant Stress Physiology, Institute of Plant Science and Resources, Okayama UniversityJian F.MaGroup of Plant Stress Physiology, Institute of Plant Science and Resources, Okayama UniversityKeiichiMochidaCrop Design Research Team, Institute of Plant Science and Resources, Okayama UniversityTakashiHirayamaGroup of Environmental Stress Response Systems, Institute of Plant Science and Resources, Okayama UniversityFE UPTAKE-INDUCING PEPTIDE1 (FEP1), also named IRON MAN3 (IMA3) is a short peptide involved in the iron deficiency response in Arabidopsis thaliana. Recent studies uncovered its molecular function, but its physiological function in the systemic Fe response is not fully understood. To explore the physiological function of FEP1 in iron homoeostasis, we performed a transcriptome analysis using the FEP1 loss-of-function mutant fep1-1 and a transgenic line with oestrogen-inducible expression of FEP1. We determined that FEP1 specifically regulates several iron deficiency-responsive genes, indicating that FEP1 participates in iron translocation rather than iron uptake in roots. The iron concentration in xylem sap under iron-deficient conditions was lower in the fep1-1 mutant and higher in FEP1-induced transgenic plants compared with the wild type (WT). Perls staining revealed a greater accumulation of iron in the cortex of fep1-1 roots than in the WT root cortex, although total iron levels in roots were comparable in the two genotypes. Moreover, the fep1-1 mutation partially suppressed the iron overaccumulation phenotype in the leaves of the oligopeptide transporter3-2 (opt3-2) mutant. These data suggest that FEP1 plays a pivotal role in iron movement and in maintaining the iron quota in vascular tissues in Arabidopsis.No potential conflict of interest relevant to this article was reported.Nature PortfolioActa Medica Okayama2041-17231212021Structural basis for high selectivity of a rice silicon channel Lsi16236ENYasunoriSaitohResearch Institute for Interdisciplinary Science, Okayama UniversityNamikiMitani-UenoInstitute of Plant Science and Resources, Okayama UniversityKeisukeSaitoResearch Center for Advanced Science and Technology, The University of TokyoKengoMatsukiGraduate School of Natural Science and Technology, Okayama UniversityShengHuangInstitute of Plant Science and Resources, Okayama UniversityLingliYangResearch Institute for Interdisciplinary Science, Okayama UniversityNaokiYamajiInstitute of Plant Science and Resources, Okayama UniversityHiroshiIshikitaResearch Center for Advanced Science and Technology, The University of TokyoJian-RenShenResearch Institute for Interdisciplinary Science, Okayama UniversityJian FengMaInstitute of Plant Science and Resources, Okayama UniversityMichihiroSugaResearch Institute for Interdisciplinary Science, Okayama UniversitySilicon (Si), the most abundant mineral element in the earthfs crust, is taken up by plant roots
in the form of silicic acid through Low silicon rice 1 (Lsi1). Lsi1 belongs to the Nodulin 26-like
intrinsic protein subfamily in aquaporin and shows high selectivity for silicic acid. To uncover
the structural basis for this high selectivity, here we show the crystal structure of the rice Lsi1
at a resolution of 1.8 Å. The structure reveals transmembrane helical orientations different
from other aquaporins, characterized by a unique, widely opened, and hydrophilic selectivity
filter (SF) composed of five residues. Our structural, functional, and theoretical investigations
provide a solid structural basis for the Si uptake mechanism in plants, which will contribute to
secure and sustainable rice production by manipulating Lsi1 selectivity for different
metalloids.No potential conflict of interest relevant to this article was reported. Oxford University PressActa Medica Okayama0022-09577162019Decrosslinking enables visualization of RNA-guided endonuclease-in situ labeling signals for DNA sequences in plant tissues17921800ENK.NagakiN.YamajiInstitute of Plant Science and Resources, Okayama UniversityInformation about the positioning of individual loci in the nucleus and the status of epigenetic modifications at these loci in each cell contained in plant tissue increases our understanding of how cells in a tissue coordinate gene expression. To obtain such information, a less damaging method of visualizing DNA in tissue that can be used with immunohistochemistry is required. Recently, a less damaging DNA visualization method using the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/associated caspase 9) system, named RNA-guided endonuclease-in situ labeling (RGEN-ISL), was reported. This system made it possible to visualize a target DNA locus in a nucleus fixed on a glass slide with a set of simple operations, but it could not be applied to cells in plant tissues. In this work, we have developed a modified RGEN-ISL method with decrosslinking that made it possible to simultaneously detect the DNA loci and immunohistochemistry signals, including histone modification, in various types of plant tissues and species. No potential conflict of interest relevant to this article was reported.Nature Publishing GroupActa Medica Okayama2041-172362015AtPHT4;4 is a chloroplast-localized ascorbate transporter in ArabidopsisENTakaakiMiyajiTakashiKuromoriYuTakeuchiNaokiYamajiKengoYokoshoAtsushiShimazawaErikoSugimotoHiroshiOmoteJian FengMaKazuoShinozakiYoshinoriMoriyamaAscorbate 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.No potential conflict of interest relevant to this article was reported.