Screening And Preliminary Analysis Of Arabidopsis RopGEFs Gene In The ROP10-dependent ABA Signaling Pathway

Small G protein ROPs (Rho-related GTPase from plants) plays pivotal roles in plant growth, development and signal transduction by acting as "molecular switches" ROP10 participents specifically in the negative regulation of ABA signaling, but its signaling mechanism remains poorly understood. RopGEFs (guanine nucleotide exchange factor) acted as an up-regulator to catalyse the ROPs cycling between actived sate and inactived sate. It have been cloned 14 RopGEFs in Arabidopsis. The screening of the RopGEFs as a regulator in ROP10-dependent ABA signaling pathway may help us to understand the ABA transduction pathway and its mechanism.1) The tissue-specific expressions of RopGEFs in Arabidopsis thaliana was confirmed. Then the expression profiles of ROP10 and RopGEFs seedlings in response to ABA with different concentration and time-course were detected and different RopGEFs showed verious expression characters. These results suggest that RopGEF1,2,3,5,11 and 14 may participant in ABA signal transdution.2) The expression of ROP10 in RopGEFs T-DNA insert mutants was measured in response to ABA. The results show that expression levels of ROP 10 appeared differently in these mutants under ABA treatment. The RopGEF1 may play a role in ROP10-dependent ABA signaling pathway as its expression was almost not affected by ABA concentration. The RopGEF 2,5,11 and 14 may also invole in ABA signal transdution by other regulation pahtway.3) The phenotypes such as seed germination rate, root length, stomatal aperture and water loss between the mutants and wild-type under ABA treatment were observed and there was no obvious distinction could be found between the mutants and the wide type. This may be explained by the gene redundancy. More detailed functional study for the preliminary screened RopGEFs in this work will be followed in the future.