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

Abstract

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 (P i) 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 P i starvation. Increased transcription of PvPS2:1 in response to P i starvation was further verified through histochemical analysis of PvPS2:1 promoter fusion ß-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 P i 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 P i starvation, and could be further targeted as a candidate gene to improve crop P efficiency. © 2012 Institute of Botany, Chinese Academy of Sciences.