Nodulin PvNOD33, a putative phosphatase whose expression is induced during Phaseolus vulgaris nodule development

We have isolated a full-length cDNA clone, designated as Pvnod33, that is highly expressed during the later stages of Phaseolus vulgaris nodule development. Pvnod33 mRNA encodes a deduced polypeptide of 263 amino acids, showing similarity to a number of putative plant phosphatases-hydrolases. This hypothesis is strengthened by the presence of a conserved motif found in several bacterial and yeast phosphatases. Using reverse-transcription-polymerase chain reaction (RT-PCR) analysis, we detected that Pvnod33 gene transcripts accumulate at high levels in mature nodules of P. vulgaris, 3 weeks after infection with rhizobia. Pvnod33 is also expressed, albeit at low levels, in nonsymbiotic tissues, including roots, flowers, seedpods, leaves and stems. In situ hybridization indicated that Pvnod33 mRNA is highly abundant in infected cells of nodules 21 d post-infection, in the nodule inner cortex, as well as in the vascular bundle of the adjacent root. Detectable levels of Pvnod33 transcripts were also observed in the xylem and phloem sclerenchymatic cells of other common bean tissues, including uninfected roots, lateral roots and stems. Taking together all these data, we propose that PvNOD33 protein may belong to a novel class of phosphatases widespread in the plant kingdom, possibly involved in carbon metabolism.