SVB1 And SVB2 Regulate ABA Response And Plant Morphology In Arabidopsis Thaliana

Abscisic acid(ABA)is a key stress hormone that regulates morphological and physiological aspects of plant growth and development.Accumulated numbers of genes from Arabidopsis thaliana have been reported to be involved in ABA signaling and stress regulation,however,some ABA responsive genes still remained unidentified.In this study,we report the identification of At4g24130(SVB1)and At1g56580(SVB2)as ABA responsive genes in Arabidopsis.Quantitative RT-PCR results revealed that the expression levels of SVB1 and SVB2 increased significantly in response to ABA treatment.Protoplast transfection assays showed that both SVB1 and SVB2 are located in the entire cell except nucleus.RT-PCR analysis showed that both SVB1 and SVB2 are highly expressed in mature flowers but SVB2 is also expressed in stems,leaves,and siliques.Seed germination analysis revealed that SVB2 overexpression and svb1 single and svb1 svb2 double mutant transgenic plants were more sensitive to ABA.However,svb2 single mutant showed less sensitivity to ABA and germinated early when compared with Col.Cotyledon greening assay showed that 35S:SVB2 transgenic plants and svb1 svb2 double mutants were more sensitive to ABA.NaCl assay showed that SVBs function redundantly in salt stress.Morphological phenotypic observation revealed that SVB2 overexpression transgenic plants have bigger seeds and longer roots as compare to control.Microscopic observation showed that svb2 mutant produce fewer trichomes,and that the numbers of trichome with 1 and 2 branches were significantly increased when compared to control.Taken together,our results suggest that SVBs are involved in the regulation of ABA response and plant morphology in Arabidopsis.