title: Alanine aminotransferase 1 (OsAlaAT1) plays an essential role in the regulation of starch storage in rice endosperm.
abstract: Alteration of storage substances, in particular the major storage form starch, leads to floury endosperm. Because floury mutants have physical attributes for milling processes, identification and characterization of those mutants are valuable. In this study we identified a floury endosperm mutant caused by a T-DNA insertion in Oryza sativa alanine-aminotransferase1 (OsAlaAT1). OsAlaAT1 is localized in the cytosol and has aminotransferase enzyme activity. The osalaat1 mutant has less amylose and its amylopectin is structurally altered. OsAlaAT1 is predominantly expressed in developing seeds during active starch synthesis. AlaAT catalyzes the interconversion of pyruvate to alanine, and this pathway is activated under low-oxygen conditions. Consistently, OsAlaAT1 is induced by such conditions. Expression of the starch synthesis genes AGPases, OsSSI, OsSSIIa, and OsPPDKB is decreased in the mutant. Thus, our observations suggest that OsAlaAT1 plays an essential role in starch synthesis in developing seeds that are exposed to low concentrations of oxygen.
authors.affiliation: Crop Biotech Institute & Department of Plant Molecular Systems Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea.
authors.forename: Jungil
authors.initials: J
authors.lastname: Yang
authors.affiliation: Plant Breeding, Genetics and Biotechnology Division, International Rice Research Institute, Metro Manila, Philippines.
authors.forename: Sung-Ryul
authors.initials: SR
authors.lastname: Kim
authors.affiliation: Crop Biotech Institute & Department of Plant Molecular Systems Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea; Department of Genetic Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea.
authors.forename: Sang-Kyu
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Crop Biotech Institute & Department of Plant Molecular Systems Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea; Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
authors.forename: Heebak
authors.initials: H
authors.lastname: Choi
authors.affiliation: Crop Biotech Institute & Department of Plant Molecular Systems Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea; Department of Genetic Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea.
authors.forename: Jong-Seong
authors.initials: JS
authors.lastname: Jeon
authors.affiliation: Crop Biotech Institute & Department of Plant Molecular Systems Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea; Department of Genetic Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea. Electronic address: genean@khu.ac.kr.
authors.forename: Gynheung
authors.initials: G
authors.lastname: An
mesh_terms: D000410:Alanine Transaminase / Q000235:genetics* / Q000378:metabolism; D000687:Amylopectin / Q000378:metabolism*; D000688:Amylose / Q000378:metabolism*; D056625:Endosperm / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000201:enzymology* / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D000688:Amylose; D000687:Amylopectin; D000410:Alanine Transaminase
keywords: Alanine aminotransferase; Carbon metabolism; Floury endosperm; Rice; Starch synthesis