The V‐PLC3 gene encodes a putative plasma membrane‐localized phosphoinositide‐specific phospholipase C whose expression is induced by abiotic stress in mung bean (Vigna radiata L.)1

Open Access
Publisher Website
Google Scholar
Abstract
Phosphoinositide‐specific phospholipase C (PI‐PLC) catalyzes the hydrolysis of phosphatidylinositol 4,5‐bisphosphate to generate inositol 1,4,5‐trisphosphate and diacylglycerol, both of which act as secondary messengers in animal cells. In this report, we identified in Vigna radiata L. (mung bean) three distinct partial cDNAs (pVr‐PLC1, pVr‐PLC2, and pVr‐PLC3), which encode forms of putative PI‐PLC. All three Vr‐PLC genes were transcriptionally active and displayed unique patterns of expression. The Vr‐PLC1 and Vr‐PLC2 transcripts were constitutively expressed to varying degrees in every tissue of mung bean plants examined. In contrast, the Vr‐PLC3 mRNA level was very low under normal growth conditions and was rapidly induced in an abscisic acid‐independent manner under environmental stress conditions (drought and high salinity). An isolated genomic clone, about 8.2 kb in length, showed that Vr‐PLC1 and Vr‐PLC3 are in tandem array in the mung bean genome. The predicted primary sequence of Vr‐PLC3 (M r=67.4 kDa) is reminiscent of the δ‐isoform of animal enzymes which contain core sequences found in typical PI‐PLCs, such as the catalytic domain comprising X and Y motifs, a lipid‐binding C2 domain, and the less conserved EF‐hand domain. Results of in vivo targeting experiment using a green fluorescent protein (GFP) showed that the GFP‐Vr‐PLC3 fusion protein was localized primarily to the plasma membrane of the Arabidopsis protoplast. The C2 domain was essential for Vr‐PLC3 to be targeted to the plasma membrane. The possible biological functions of stress‐responsive Vr‐PLC3 in mung bean plants are discussed.