Preliminary Research On RopGEFs In The Signaling Of ROP10 Negative Regulation With ABA In Arabidopsis

Abscisic acid (ABA) is an important plant hormone that modulates plant seed germination, growth and stress responses. So, its makes perfect sense to research on the ABA signaling. As a key regulatory component, Rho-related GTPase from plants(ROPs) regulate plant signal transduction in fundamental processes such as hormone signaling, polar growth, differentiation, and adaptation to abiotic stress situations. The activation of ROPs needs the catalysis of ROP guanine nucleotide exchange factor (RopGEFs) with the conversion from the inactive GDP-bound form to the active GTP-bound form. ROP10, a member of ROPs, is a specific negative regulator of ABA responses in Arabidopsis. However, the role of RopGEFs in ROP10–independent ABA signaling pathway remains undefined.In order to identify RopGEFs which may participate in the signaling of ROP10 specificly negetive regulating of ABA, research work was carried out as follow and some favorable data and creative results have been achieved.(1) Bioinformatics analysis of RopGEFs and ROP10. Microarry data indicates that most of RopGEFs was down-regulated by ABA. 4 RopGEFs were predicted from STRING database as functional partners of ROPs. These results demonstrate that RopGEFs and ROPs may share a closely interaction.(2)The expression profiles detection of RopGEFs by real-time PCR. 7 days old seedlings of wide type Arabidopsis Ws was taken to analyze its RopGEFs expression characters to identify the expression tissue specifity. The result showed that the expression of RopGEFs was different. Compared with RopGEF1, 4, 6, 7 and 14, the expression of RopGEF 8, 9 and 10 were hardly detected. Then, the expression of RopGEFs in the seedlings of wide type Ws, null ROP10 mutant rop10-1 and constitutive activate mutant CA-rop10 under different concentration ABA treatment were investigated. Our data indicates that most RopGEFs were involved in ABA signaling. What’s more, RopGEF1, 11 and14 showed similar expression profiles under ABA treatment and all down-regulated by ABA. So we presume that RopGEFs might share redundancy activities toward ROP10.(3) Homozeygote confirmation with the T-DNA insert mutant of RopGEFs and the expression level analysis of ROP10 and MYB2 mRNA. So far 7 homozeygote lines and two heterozygote lines were confirmed. All the mutants and the expression data of related gene can provide reliable materials and theoretical basis for further research.