Abstract
In Arabidopsis, the induction of a dehydration-responsive gene, RD22, is mediated by ABA.Previous experiments have established that MYC- and MYB-recognition sites in the RD22 promoter function as cis-acting elements in the dehydration-induced gene expression. A MYC-related factor (AtMYC2) and a MYB-related factor (AtMYB2) have been isolated. We have shown that transgenic plants overexpressing AtMYC2 or AtMYB2 cDNA displayed ABA hypersensitivity. Transgenic plants overexpressing both AtMYC2 and AtMYB2 cDNAs showed a higher level of ABA hypersensitivity than that of transgenic plants overexpressing either AtMYC2 or AMYB2 cDNA. ABA induced gene expression of the RD22 gene also showed the ABA hypersensitivity. Moreover, a Ds-insertion mutant of the AtMYC2 gene (atmyc2) showed ABA insensitivity. In atmyc2 mutants, ABA induced gene expression of the RD22 gene was significantly decreased. In this meeting, we will show the results of microarray analysis and discuss about the function of AtMYC2 and AtMYB2 proteins in ABA signaling.
