Study On The Function Of CIPK1 Gene In Arabidopsis

A new type of Ca²⁺ sensors unique to Arabidopsis have been studied recently, they are the so-called CBLs for their similarity to B-subunit of yeast and animal calcineurin. Plant CBLs interact with and regulate the activity of a group of Ser/Thr protein kinases, referred to as CIPKs. The analysis of CBLs and CIPKs families revealed that they play an important role in the stress signal transduction pathway of higher plants. But there is no report about CIPK1 genefunction in the signal pathway of stress. So, in this research, we cloned CIPK1 gene form Arabidopsis and screened mutants, so as to research the role of CIPK1 gene in the signal pathway of ABA seed dormancy regulation.The results of this study were listed as follows:RT-PCR was used for the analysis of the expression level of CIPK1 gene, and it was found that CIPK1 gene was constitutively expressed in Arabidopsis roots, stems, leaves, flowers and siliques. In stems and flowers it was mostly expressed, and least in leaves. The expression of CIPK1 gene increased to the maximum with ABA for 1h, and decreased with GA, However, it restored to the original with GA after 2h in Arabidopsis. The expression of CIPK1 gene was up-regulated slightly by 6-BA and 2,4-D. These results indicated that the expression CIPK1 gene was involved in response to ABA stress.To better understand the role of CIPKl gene in stress-responsive pathway, we firstly cloned the CIPKl gene using Gateway technology, then we transform it to wild type (WT). By screening the transgenic mutants with baster, several co-suppression mutants were obtained. After being treated with ABA, differences in physiology between Arabidopsis cipk1 mutant and wild type (WT) were analyzed. Treated with 0.2μM and 0.4μM ABA for 5d, the germination frequency of cipk1 mutant was 76% and 43%, and the germination frequency of WT was 47% and 10%. All the results showed that the germination frequency of cipk1 mutant was higher than that of WT under ABA stress and the CIPK1 gene plays an important role in regulating seed dormancy to ABA signal. Taken together, our data provide evidence that CIPK1 gene encodes a receptor like kinase essential in regulating seed dormancy to ABA signal. These results certainly helped to do further studies on establishing ABA-independent signal transduction in plants and provide academic base to breeding work.