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Biochemical and molecular characterization of rice ( O ryza sativa L .) roots forming a barrier to radial oxygen loss
Author(s) -
KULICHIKHIN KONSTANTIN,
YAMAUCHI TAKAKI,
WATANABE KOHTARO,
NAKAZONO MIKIO
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12294
Subject(s) - plastid , suberin , malic acid , biochemistry , oryza sativa , biosynthesis , fatty acid , biology , cell wall , chemistry , enzyme , gene , chloroplast , citric acid
The formation of a barrier to radial oxygen ( O 2 ) loss ( ROL ) in the root is an important adaptation of plants to root flooding, but the biochemical changes in plant roots where the barrier is formed are unclear. In this study, we analysed metabolic profiles and gene expression profiles in roots of rice ( O ryza sativa L .) plants grown under stagnant deoxygenated conditions, which induce suberization in the outer cell layers of the roots and formation of barrier to ROL . Under these conditions, two distinctive biochemical features of the roots were the accumulations of malic acid and very long chain fatty acids ( VLCFAs ). We also showed that the expressions of some genes encoding plastid‐localized enzymes, which convert malic acid to acetyl coenzyme A ( AcCoA ), were simultaneously up‐regulated under stagnant conditions. The expression levels of these genes in specific root tissues isolated by laser microdissection suggested that malic acid is converted to AcCoA predominantly in the plastids in the outer cell layers of rice roots. We propose that the physiological role of malic acid accumulation in rice roots grown under stagnant conditions is to provide a substrate for the biosynthesis of fatty acids, which, in turn, are used in the biosynthesis of suberin.