Characterization of Two Putative Protein Phosphatase Genes and Their Involvement in Phosphorus Efficiency in Phaseolus vulgaris

Protein dephosphorylation mediated by protein phosphatases plays a major role in signal transduction of plant responses to environmental stresses. In this study, two putative protein phosphatases, PvPS2：1 and PvPS2：2 were identified and characterized in bean （Phaseolus vulgaris）. The two PvPS2 members were found to be localized to the plasma membrane and the nucleus by transient expression of PvPS2：GFP in onion epidermal cells. Transcripts of the two PvPS2 genes were significantly increased by phosphate （P1） starvation in the two bean genotypes, G19833 （a P-efficient genotype） and DOR364 （a P-inefficient genotype）. However, G19833 exhibited higher PvPS2：1 expression levels than DOR364 in both leaves and roots during P1 starvation. Increased transcription of PvPS2：1 in response to P1 starvation was further verified through histochemical analysis of PvPS2：I promoter fusion b-glucuronidase （GUS） in transgenic Arabidopsis plants. Analysis of PvPS2：1 overexpression lines in bean hairy roots and Arabidopsis showed that PvS2：1 was involved in root growth and P accumulation. Furthermore, expression levels of two P1 starvation responsive genes were upregulated and the APase activities were enhanced in the overexpressing PvPS2：1 Arabidopsis lines. Taken together, our results strongly suggested that PvPS2：1 positively regulated plant responses to P1 starvation, and could be further targeted as a candidate gene to improve crop P efficiency.