Identification & Functional Characterization of the AtZFP3

Seed germination is controlled by environmental signals, including light and endogenous phytohormones. Abscisic acid (ABA) inhibits, whereas gibberellin (GA) promotes germination and early seedling development, respectively. Here we report that ZFP3, a nuclear C2H2 zinc finger protein acts as a negative regulator of ABA- suppressed germination. Accordingly, regulated over-expression of ZFP3 and the closely related ZFP1, ZFP4, ZFP6 and ZFP7 zinc finger factors confers ABA insensitivity to seed germination while the zfp3 zfp4 double mutant displays enhanced ABA susceptibility. Reduced expression of several ABA-induced genes, such as RAB18 and transcription factor ABI4 in ZFP3ox seedlings suggests that ZFP3 negatively regulates ABA signaling. Analysis of ZFP3ox plants revealed multiple phenotypic alterations, such as semidwarf growth habit, defects in fertility and enhanced sensitivity of hypocotyl elongation to red but not to far-red or blue light. Analysis of genetic interactions with phytochrome and abi mutants indicates that ZFP3 regulate light and ABA responses during germination and early seedling development.