The Identification And Functional Analysis Of MAPKKK In ABA Signaling Pathway In Arabidopsis

Plants has formed a complete and complex signal transduction pathways about the responses to theexternal stimuli in its long-term evolutionary process. MAPK cascade is very important in the signaltransduction pathways. Components of the MAPK cascade in eukaryotes is very conservative；thephosphorylation cascades including for MAPK, MAPKK and MAPKKK, they activated by their specificamino acid phosphorylation, MAPK activated by MAPKK, MAPKK are themselves activated byMAPKKK through phosphorylation of conserved amino acid cascade. MAPK cascade extensively involvedin the signal transduction process when the plant suffer a variety of biotic and abiotic stress. ABA is a veryimportant plant hormones, play an important role in plant seed dormancy, germination, and are associatedwith various abiotic stress, such as drought, low temperature, ion permeability. It is concern that ABAmolecular mechanism of stress response in plant. A large number of studies have been shown that theMAPK cascade is involved in ABA-mediated signal transduction process, but there is not a completeMAPK cascade pathway of signaling pathways have been reported.In this paper, we have a preliminary analysis of AATK1and its homologous genes response to ABA inplant. We obtained AATK1and its homologous genes T-DNA insertion lines and isolated aatk1and otherhomozoygous mutants by PCR. the RT-PCR shows, expression of gene in these mutants is knock down.weanalysis phenotypic of single mutants by exogenous ABA treatment. we found the aatk2performance ABAinsensitive phenotype, aatk5-1, aatk8-3and MPK9show the ABA-sensitive phenotype. Compared with WT,aatk1bigger water loss rate and lower leaf temperature, but compared with WT other mutants have not much difference. We found that the single mutant gene expression appears to reduce by RT-PCR, but thegene expression is rising after treatment with ABA.And then we got double deletion mutant by the hybridmethod, we analysis phenotypic of these ten double mutants under the ABA treatment, The germinationrate of aatk1aatk2and aatk1aatk8-3were lower than wild type when treated with ABA, while the doublemutant aatk5-1aatk8-3show the ABA super-sensitive phenotype. At the same time is found water loss rateof aatk1aatk2, aatk1aatk8-3is greater than WT and the leaf temperature is lower, but double mutantaatk5-1aatk8-3is contrary to the both.These studies have shown that: aatk1, aatk2, aatk5-1, aatk8-3and MPK9are involved inABA-mediated signal transduction in plants, but their functional redundancy.