Overexpression of Arabidopsis PP2CA2 gene shows phenotypes related to abscisic acid responses

In this study we overexpressed PP2CA2 gene in Arabidopsis to provide genetic evidence on this gene function in seed germination and other plant responses. The average seed germination percentage of constitutive expression of AtPP2CA2 under a cauliflower mosaic virus 35S promoter (35S::AtPP2CA2) was lower than that of wild type under 0.3 and 1 uM exogenous abscisic acid (ABA), indicating an increased sensitivity of 35S::AtPP2CA2 seeds to ABA with respect to wild type. The35S::AtPP2CA2 seedlings showed an increased inhibition of root growth compared with wild-type plants. In the absence of exogenous ABA, the water loss in35S::AtPP2CA2 plants was lower than that in wild type. There is no obvious difference of water loss between 35S::AtPP2CA2 and wild type plants under 10 uM ABA treatment. The 35S::AtPP2CA2 plants had smaller stomatal apertures than did wild-type plants under ABA treatment. Furthermore, the 35S::AtPP2CA2 seedlings showed a reduced inhibition of hypocotyl growth compared with wild-type plants under the 0, 10, 20, 30 and 40 uM exogenous ABA. The study on overexpression of AtPP2CA2gene could provide an approach for improving crop performance under stress conditions.   Key words: Arabidopsis, AtPP2CA2 gene, phenotype, abscisic acid signal transduction.