【摘要】 赤霉素(gibberellin,GA)是一种重要的植物激素,它与光敏色素协同调节拟南芥植株的光形态建成特征.但是GA对水稻幼苗光形态建成和暗形态建成的影响,特别是在此过程中光敏色素与GA之间的相互作用仍不清楚.本研究利用野生型和光敏色素突变体(phyA和phyB)水稻作为研究材料,分析了GA生物合成抑制剂多效唑(PAC)对黑暗和光照下生长的水稻幼苗胚芽鞘、地上部分和主根延伸以及光调控基因LHCB表达的影响.据此推测,在暗生长条件下,PAC处理能够抑制野生型水稻幼苗胚芽鞘的生长,诱导LHCB基因的表达;phyA突变体对PAC处理的反应不如野生型敏感;phyB突变体和野生型反应基本相同.在光照条件下,PAC处理能够抑制水稻幼苗地上部分的生长,phyB突变体对PAC处理的反应不如野生型和phyA突变体敏感.此外,phyB介导的光信号负调控PAC诱导的主根延伸反应.据此推测,GA是维持水稻幼苗暗形态建成、抑制光形态建成所必需的;另一方面,phyA和phyB或正或负调控PAC所诱导的光形态建成反应.本研究结果揭示了光敏色素和GA在水稻幼苗生长发育中的相互作用,为进一步研究光和GA协同调控水稻发育的分子机制奠定了基础.更多还原

【Abstract】 Gibberellin(GA) is an important plant hormone,which,together with phytochrome-mediated light signals,regulates Arabidopsis thaliana development.However,roles of GA and its interaction with phytochromes in mediating skotomorphogenesis and photomorphogenesis remain unclear in rice.In the present study,the lengths of coleoptiles,seminal roots and up-ground parts were measured in either dark-or white light-grown seedlings treated with GA biosynthesis inhibitor PAC in wild type and rice phytochrome mutants.Meantime,transcript levels of light-regulated genes LHCB were also analyzed.It was observed that PAC treatment caused the inhibition of coleoptile elongation and induction of LHCB genes in dark-grown seedlings.Moreover phyA mutant exhibited less sensitive to PAC than wild type and phyB mutant in dark-grown seedlings.In white light-grown seedlings,growth of up-ground parts was inhibited by PAC while phyB mutant exhibited less sensitive than wild type and phyA mutant did.In addition,phyB antagonistically affect the inductive responses of root elongation triggered by PAC in light-grown seedlings.These results suggest that GA is necessary to maintain skotomorphogenesis and to suppress photomorphogenesis in dark-grown rice seedlings.In addition,phyA and phyB either negatively or positively affect responses caused by PAC treatment in rice seedlings.For the first time,our findings reveal the interaction between phytochrome-and GA-mediated pathways which lays the foundation for dissecting the molecular mechanism of coordinated regulation of rice development by light and GA.更多还原