Rice PLASTOCHRON genes regulate leaf maturation downstream of the gibberellin signal transduction pathway
Rice PLASTOCHRON genes regulate leaf maturation downstream of the gibberellin signal transduction pathway
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DOI：
10.1007/s00425-012-1639-5
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发表时间：
2012-05-01
期刊：
影响因子：
4.3
通讯作者：
Itoh, Jun-Ichi
中科院分区：
文献类型：
--
作者：
Mimura, Manaki;Nagato, Yasuo;Itoh, Jun-Ichi
水稻PLASTOCHRON 1（PLA 1）和PLA 2基因调节叶片成熟和质体时程，并且它们的功能丧失突变体表现出小器官和快速叶片出现。它们分别编码细胞色素P450蛋白CYP 78 A11和RNA结合蛋白。它们在拟南芥和玉米中的同源物也与植物发育/器官大小相关。尽管PLA基因在植物发育中的重要性，但它们的分子功能仍然未知。在这里，我们研究了PLA 1和PLA 2基因是如何与植物激素相关的。我们发现赤霉素（GA）是促进PLA 1和PLA 2表达的主要植物激素。GA诱导PLA 1和PLA 2的表达，反之，GA抑制剂烯效唑抑制PLA 1和PLA 2的表达。在pla 1 -4和pla 2 -1幼苗中，GA生物合成基因和信号转导基因的表达水平与野生型幼苗相似。GA处理轻微下调GA生物合成基因GA 20 ox 2和上调GA分解代谢基因GA 2 ox 4，而GA生物合成抑制剂烯效唑上调GA 20 ox 2和下调GA 2 ox 4在野生型和pla突变体中，表明GA反馈机制在pla 1和pla 2中没有受损。为了揭示GA信号转导如何影响PLA 1和PLA 2的表达，检测了GA信号转导突变体中的PLA表达。在GA不敏感突变体、gid 1和低敏感突变体中，Slr 1-d1、PLA 1和PLA 2表达下调。另一方面，PLA 1和PLA 2的表达水平在GA组成型活性突变体slr 1 -1中高度增强，引起异位过表达。这些结果表明，PLA 1和PLA 2的GA信号转导途径下游的行为，以调节叶片发育。
Rice PLASTOCHRON 1 (PLA1) and PLA2 genes regulate leaf maturation and plastochron, and their loss-of-function mutants exhibit small organs and rapid leaf emergence. They encode a cytochrome P450 protein CYP78A11 and an RNA-binding protein, respectively. Their homologs in Arabidopsis and maize are also associated with plant development/organ size. Despite the importance of PLA genes in plant development, their molecular functions remain unknown. Here, we investigated how PLA1 and PLA2 genes are related to phytohormones. We found that gibberellin (GA) is the major phytohormone that promotes PLA1 and PLA2 expression. GA induced PLA1 and PLA2 expression, and conversely the GA-inhibitor uniconazole suppressed PLA1 and PLA2 expression. In pla1-4 and pla2-1 seedlings, expression levels of GA biosynthesis genes and the signal transduction gene were similar to those in wild-type seedlings. GA treatment slightly down-regulated the GA biosynthesis gene GA20ox2 and up-regulated the GA-catabolizing gene GA2ox4, whereas the GA biosynthesis inhibitor uniconazole up-regulated GA20ox2 and down-regulated GA2ox4 both in wild-type and pla mutants, suggesting that the GA feedback mechanism is not impaired in pla1 and pla2. To reveal how GA signal transduction affects the expression of PLA1 and PLA2, PLA expression in GA-signaling mutants was examined. In GA-insensitive mutant, gid1 and less-sensitive mutant, Slr1-d1, PLA1 and PLA2 expression was down-regulated. On the other hand, the expression levels of PLA1 and PLA2 were highly enhanced in a GA-constitutive-active mutant, slr1-1, causing ectopic overexpression. These results indicate that both PLA1 and PLA2 act downstream of the GA signal transduction pathway to regulate leaf development.