title: Amyloplast Membrane Protein SUBSTANDARD STARCH GRAIN6 Controls Starch Grain Size in Rice Endosperm.
abstract: Starch is a biologically and commercially important polymer of glucose. Starch is organized into starch grains (SGs) inside amyloplasts. The SG size differs depending on the plant species and is one of the most important factors for industrial applications of starch. There is limited information on genetic factors regulating SG sizes. In this study, we report the rice (Oryza sativa) mutant substandard starch grain6 (ssg6), which develops enlarged SGs in endosperm. Enlarged SGs are observed starting at 3 d after flowering. During endosperm development, a number of smaller SGs appear and coexist with enlarged SGs in the same cells. The ssg6 mutation also affects SG morphologies in pollen. The SSG6 gene was identified by map-based cloning and microarray analysis. SSG6 encodes a protein homologous to aminotransferase. SSG6 differs from other rice homologs in that it has a transmembrane domain. SSG6-green fluorescent protein is localized in the amyloplast membrane surrounding SGs in rice endosperm, pollen, and pericarp. The results of this study suggest that SSG6 is a novel protein that controls SG size. SSG6 will be a useful molecular tool for future starch breeding and applications.
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.) rmatsu@okayama-u.ac.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Matsushima
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Masahiko
authors.initials: M
authors.lastname: Maekawa
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Miyako
authors.initials: M
authors.lastname: Kusano
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Katsura
authors.initials: K
authors.lastname: Tomita
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Hideki
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Hideki
authors.initials: H
authors.lastname: Nishimura
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Naoko
authors.initials: N
authors.lastname: Crofts
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Naoko
authors.initials: N
authors.lastname: Fujita
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan (R.M., M.M., H.K., H.N., W.S.);Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan (M.K.);RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan (M.K.);Fukui Agricultural Experiment Station, Fukui 918-8215, Japan (K.T.); andDepartment of Biological Production, Akita Prefectural University, Akita 010-0195, Japan (N.C., N.F.).
authors.forename: Wataru
authors.initials: W
authors.lastname: Sakamoto
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003594:Cytoplasmic Granules / Q000235:genetics / Q000378:metabolism; D056625:Endosperm / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011058:Pollen / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000378:metabolism*; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins; D049452:Green Fluorescent Proteins; D013213:Starch; D000637:Transaminases; C000612720:substandard starch grain6 protein, rice