ISOLATION, CLONING AND PARTIAL CHARACTERIZATION OF THE GENE ENCODING THE POLYGALACTURONASE INHIBITING PROTEIN OF PHASEOLUS VULGARIS CV. NAZ

Abstract

In this research, inhibitory effect of bean (Phaseolus vulgaris cv. Naz and cv. Derakhshan) hypocotyl PGIP on the PG enzymes from highly virulent isolates of Fusarium oxysporum (F15) and Ascochyta rabiei (IK04) was analyzed. It was shown that PGIPs from Naz and Derakhshan cultivars inhibit more effectively the PG activity of F. oxysporum (F15) than PG activity of A. rabiei (IK04). The inhibitory activity of Naz and Derakhshan PGIP on PG activity of these fungi demonstrated that Derakhshan PGIP was able to inhibit the PG activity of F. oxysporum by 55% and A. rabiei by 40%. Naz cultivar PGIP had reduced ability to inhibit PG activity from F. oxyspoum and A. rabiei by 40 and 26%, respectively. The pgip gene was amplified from Naz cultivar genomic DNA, cloned and sequenced. Comparison of DNA sequence and deduced amino acid from Naz cultivar with those of Derakhshan and Saxa cultivars indicates that it differs only in a single nucleotide (G) in position 880 which alters amino acid T to A at position 294. This amino acid is located in LRR9 region of PGIP. Also, the cloned pgip was shown to encode a 37 kDa polypeptide corresponding to the deduced polypeptide molecular weight. The data from this study suggestes possible role for this amino acid change in LRR9 region in specificity of PGIP-PG interaction