百脉根小GTPase激活蛋白的鉴定及突变体分离

以豆科植物百脉根为材料,利用蛋白质相互作用技术、基因表达分析和突变体表型观察研究了小GTPase激活蛋白RacGAP1和RacGAP3在侧根及根瘤发育中的功能。结果表明:百脉根小GTPase激活蛋白RacGAP1和RacGAP3能与ROP6~(CA)相互作用,RacGAP1和RacGAP3基因主要在根微管组织中表达,在接种根瘤菌后呈下调表达趋势。RacGAP1在侧根及根瘤原基中无表达;RacGAP3则能在侧根及根瘤基部表达。RacGAP1和RacGAP3的LORE1插入突变体表型观察显示,纯合突变体与Gifu野生型共生表型无明显差异,但RacGAP1突变体植株开花后,花朵枯萎掉落不结荚,而杂合体与野生型无差异,表明RacGAP1可能参与调控花粉发育过程,而RacGAP3在早期共生过程中可能起负调控作用。

Characterization of small GTPase activating protein and isolation of mutant in Lotus japonicas

Two genes (RacGAP1 and RacGAP3) in Lotus japonicus were identified to explore the function of small GTPase activating protein during symbiotic process.Results of pull-down assay showed that both RacGAP1 and RacGAP3 are able to interact with ROP6CA.The result of analyzing transcrip tion showed that RacGAP1 and RacGAP3 were expressed mainly in vascular system of roots and downregulated expressed after being inoculated with Mesorhizobium loti.Promoters of the two genes were fused with GUS reporter and separately transferred into L.japonicus by hair roots transformation.The results showed that RacGAP3 was expressed in lateral root primordia and nodule primordia,but there was no expression of RacGAP1 in both primordia.RacGAP1 and RacGAP3 LORE1 insertion mutant didn't show any defects about nodulation.However,homozygous plants of RacGAP1 exhibited severe defects in reproduction with withered flowers and fewer pods in comparison with the wild-type.It is indicated that RacGAP1 may be involved in flower development and RacGAP3 may negatively regulate the early symbiotic process in L.japonicus.