12. イネ幼苗におけるGA, BR応答性チオニン遺伝子の解析

概要

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Both Gibberellin (GA) and brassinosteroid (BR) are phytohormones involved in shoot elongation. In the course of study using rice cDNA microarray to investigate the crosstalk of GA and BR signalings in young rice seedlings, we found that thionin genes showed conspicuous responsiveness to GA/BR. Northern analysis showed that thionin genes are expressed at high level in coleoptiles just after germination and decreased rapidly in 3 days to undetectable level, and GA/BR co-treatment could suppress this declination. In the present study, we analyzed the detailed localization of thionin gene expression by establishing thionin promoter-GUS transformant rice lines, and by in situ hybridization analysis. Furthermore, the possibility that the declination of thionin gene expression after germination could be interpreted as decreased hormonal levels. In thionin-pro-GUS transgenic lines, GUS activity was detected in the embryo epithelium, while in situ hybridization analysis showed that thionin mRNA was localized in coleoptile, giving an inconsistency between two analyses. In addition, the expression of OsDWARF (a BR biosynthesis enzyme gene) was correlated with that of thionin, suggesting that biosynthesis of BR may be responsible for the level of thionin gene expression.
植物化学調節学会の論文
2004-10-13