38.bHLH型タンパク質をコードするイネのブラシノステロイド誘導性遺伝子の解析(口頭発表)

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Brassinosteroids (BRs) are important for plant growth, development, photomorphogenesis and resistance to biotic and abiotic stresses. We have already isolated the brd1 dwarf mutant of rice that has a defective BR biosynthetic gene OsBR6ox. For the purpose of isolating genes associated with the BR signal, we used a 22k rice microarray to monitor the transcriptomic response of the brd1 mutant after treatment with BL. Among the up-regulated genes, we present detailed analyses of OsBU3 and OsBU17, both encoding putative bHLH proteins. Rice plants overexpressing OsBU3 (OsBU3:OX) showed severe bending of the lamina joint, a phenotype that is typically shown when BL is applied to a WT plant. In contrast, RNAi plants designed to repress both OsBU3 and its paralogues displayed erect leaves. In dark condition, the internode and mesocotyl of WT plant is elongated and treatment with brassinazole (brz), an inhibitor of BR biosynthesis, inhibits elongation. OsBU3:OX plants showed longer intemodes and mesocotyls than those of WT in the dark and showed brz resistance. Moreover, overexpression of OsBU3 complemented the erect leaf phenotype of d61, a loss of function mutant of OsBRI1, indicating that OsBU3 is involved in BR signaling but not in BR biosynthesis. In contrast to OsBU3:OX, OsBU17:OX showed erect leaves but did not show dwarfism. OsBU17 may be a rice-specific gene mainly involved in bending of the lamina joint, because it has no close orthologues in Arabidopsis and other plants.
植物化学調節学会の論文
2008-10-06

38.bHLH型タンパク質をコードするイネのブラシノステロイド誘導性遺伝子の解析(口頭発表)

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