Cloning and expression under drought of cDNAscoding for two PI-PLCs in cowpea leaves

Two cDNAs coding for putative phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.3) from cowpea leaves (Vigna unguiculata L. Walp) were cloned and characterized. These cDNAs designated VuPLC1 and VuPLC2 belong to the delta-type PI-PLCs and revealed deduced amino acid homology of 66 %. Northern blot analysis of mRNA from leaves of two V. unguiculata cultivars differing in their sensitivity to drought (drought-sensitive, 1183, and drought-tolerant, EPACE-1) showed that VuPLC1 transcript level decreased under progressive water stress in the two cultivars, whereas VuPLC2 gene expression is stimulated up to –1.5 MPa only in the tolerant cultivar. These results suggest different physiological roles for the two genes and demonstrate differential behaviour of one PI-PLC gene expression in two cultivars belonging to the same species.