title: Additional nitrogen fertilization at heading time of rice down-regulates cellulose synthesis in seed endosperm.
abstract: The balance between carbon and nitrogen is a key determinant of seed storage components, and thus, is of great importance to rice and other seed-based food crops. To clarify the influence of the rhizosphere carbon/nitrogen balance during the maturation stage of several seed components, transcriptome analysis was performed on the seeds from rice plants that were provided additional nitrogen fertilization at heading time. As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed. Moreover, cellulose and sucrose synthases, which are involved in cellulose synthesis, were down-regulated. Therefore, we compared cellulose content of mature seeds that were treated with additional nitrogen fertilization with those from control plants using calcofluor staining. In these experiments, cellulose content in endosperm from plants receiving additional nitrogen fertilization was less than that in control endosperm. Other starch synthesis-related genes such as starch synthase 1, starch phosphorylase 2, and branching enzyme 3 were also down-regulated, whereas some α-amylase and β-amylase genes were up-regulated. On the other hand, mRNA expression of amino acid biosynthesis-related molecules was up-regulated. Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression. These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Midorikawa
authors.affiliation: Crop Development Division, NARO Agricultural Research Center, Inada, Joetsu, Niigata, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kuroda
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kaede
authors.initials: K
authors.lastname: Terauchi
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Hoshi
authors.affiliation: Field Crop and Horticulture Research Division, NARO Tohoku Agricultural Research Center, Morioka, Iwate, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Ikenaga
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Ishimaru
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Food Safety and Reliability Project, Kanagawa Academy of Science and Technology, Takatsu-ku, Kawasaki, Kanagawa, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tomiko
authors.initials: T
authors.lastname: Asakura
mesh_terms: D002482:Cellulose / Q000096:biosynthesis*; D015536:Down-Regulation / Q000187:drug effects; D056625:Endosperm / Q000187:drug effects* / Q000378:metabolism*; D005308:Fertilizers; D009584:Nitrogen / Q000494:pharmacology*; D012275:Oryza / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D059467:Transcriptome / Q000187:drug effects; D047071:beta-Glucans / Q000378:metabolism
chemical_list: D005308:Fertilizers; D047071:beta-Glucans; D002482:Cellulose; D009584:Nitrogen