Transcription profiling identifies candidate genes for secondary cell wall formation and hydroxycinnamoylarabinoxylan biosynthesis in the rice internode

Abstract

Microarray analysis was used to identify candidate genes that are involved in the formation of secondary cell walls and hydroxycinnamoyl-arabinoxylan (AX) in rice. In order to identify genes involved in secondary cell wall formation, gene expression was compared between wild-type whole internodes that contain cells with thickened secondary cell walls, such as vascular and cortical fiber cells, and wild-type internode parenchyma cells without secondary cell walls. In addition, gene expression was compared between the internode parenchyma of Fukei71 (F71), a rice dwarf mutant that accumulates large amounts of hydroxycinnamoyl-AX in pith parenchyma cells, and wild-type pith parenchyma cells to identify hydroxycinnamoyl-AX-related genes. To address the significant expression of candidate genes, gene lists were prepared for the phenylpropanoid pathway, major carbon metabolism, and cell wall biosynthesis, which is a useful platform to analyze cell wall formation in rice. The data indicated that a number of rice genes are potentially associated with secondary cell wall formation, such as the up-regulation of genes encoding cellulose synthase subunit A and ferulate 5-hydroxylase in wild-type whole internodes. Similarly, for hydroxycinnamoyl-AX synthesis, the expression of several genes changed, such as the downregulation of genes encoding cinnamoyl-CoA reductase and the up-regulation of the phosphoenolpyruvate carboxykinase gene in F71 pith parenchyma. © 2013 The Japanese Society for Plant Cell and Molecular Biology.