Rice dwarf mutant d1, which is defective in the α subunit of the heterotrimeric G protein, affects gibberellin signal transduction
Rice dwarf mutant d1, which is defective in the α subunit of the heterotrimeric G protein, affects gibberellin signal transduction
复制标题
DOI：
10.1073/pnas.97.21.11638
复制
发表时间：
2000-10-10
影响因子：
11.1
通讯作者：
Matsuoka, M
中科院分区：
文献类型：
--
作者：
Ueguchi-Tanaka, M;Fujisawa, Y;Matsuoka, M
本研究以水稻矮秆突变体d1为研究对象，研究了异源三聚体G蛋白LY亚基（Col）的缺失对赤霉素（GA）信号转导的影响，并探讨了G α蛋白在GA信号转导中的作用。与野生型相比，GA对dl糊粉细胞α-淀粉酶活性的诱导作用大大降低。相对于野生型，GA（3）处理的dl糊粉层具有较低的Ramy 1A表达，其编码α-淀粉酶。关于OsGamyb其编码GA诱导的转录因子，并且不增加Ca 2 +-ATP酶的表达。然而，在高CA浓度的存在下，或-淀粉酶诱导甚至发生在dl。第二叶鞘伸长的CA敏感性在剂量反应方面与野生型相似，但节间伸长对GA的反应在dl中要低得多。此外，Os 20 ox的表达上调，GA含量增加，在矮化节间dl。所有这些结果表明，dl影响GA信号通路的一部分，即糊粉层中α-淀粉酶的诱导和节间伸长。此外，dl和另一个CA信号传导突变体sir之间的双突变体揭示了SLR对DI是上位性的，支持Cor蛋白参与GA信号传导。然而，这些数据也提供了不涉及G α蛋白的替代CA信号通路的存在的证据。有人提出，GA信号通过得到的蛋白质可能是更敏感的比替代途径，这表明低CA响应的G α非依赖性途径。
Previously, we reported that the rice dwarf mutant, d1, is defective in the LY subunit Of the heterotrimeric G protein (Col), In the present study, gibberellin (GA) signaling in dl and the role of the G alpha protein in the CA-signaling pathway were investigated. Compared with the wild type, GA induction of alpha-amylase activity in aleurone cells of dl was greatly reduced. Relative to the wild type, the GA(3)-treated aleurone layer of dl had lower expression of Ramy1A, which encodes alpha-amylase. and OsGAMYB. which encodes a GA-inducible transcriptional factor, and no increase in expression of Ca2+-ATPase. However, in the presence of high CA concentrations, or-amylase induction occurred even in dl. The CA sensitivity of second leaf sheath elongation in dl was similar to that of the wild type in terms of dose responsiveness, but the response of internode elongation to GA was much lower in dl. Furthermore, Os20ox expression was up-regulated, and the GA content was elevated in the stunted internodes of dl. All these results suggest that dl affects a part of the GA-signaling pathway, namely the induction of alpha-amylase in the aleurone layer and internode elongation. In addition, a double mutant between dl and another CA-signaling mutant, sir, revealed that SLR is epistatic to the DI, supporting that the Cor protein is involved in GA signaling. However, the data also provide evidence for the presence of an alternative CA-signaling pathway that does not involve the G alpha protein. It is proposed that GA signaling via the Got protein may be more sensitive than that of the alternative pathway, as indicated by the low CA responsiveness of this G alpha-independent pathway.