Molecular cloning of an S-adenosylmethionine synthase gene from pigeon pea (Cajanus cajan) and its expression analysis under arbuscularmycorrhizae fungi colonization and drought stress

Abstract

An S-adenosylmethionine synthase (SAMS) gene associated with the drought responsiveness was isolated and characterized from pigeon pea. It was designated CcSAMS and contained an open reading frame of 1,182 bp, which encoded 394 amino acid residues. Sequence analysis of the cloned cDNA showed 94% identity with SAMS from other plant species, suggesting that this gene was considerably conserved in plants. Gene expression analysis demonstrated that CcSAMS was highly expressed in the leaves of AM-colonized plants, irrespective of exposure to either drought or drought-free. Rather, the expression levels of AM plants were significantly higher than that of NAM plants as subjected to drought stress. Therefore, AM symbiosis might enhance the expression of CcSAMS, and the elevated tolerance of AM-colonized pigeon pea to drought-stress was at least partially ascribed to the overexpression of SAMS gene.