Bean Polygalacturonase-inhibiting Protein Expressed in Transgenic Brassica napus Inhibits Polygalacturonase from its Fungal Pathogen Rhizoctonia solani

Polygalacturonase-inhibiting proteins (PGIPs) selectively inhibit polygalacturonases (PGs) secreted by invading plant pathogenic fungi. The objective of present research was to clone and introduce the pgip2 gene from bean (Phaseolus vulgaris) cv. Goli, with antifungal potential, into the commercially important canola (Brassica napus, R line Hyola 308) via Agrobacterium tumefaciens mediated transformation. Here we used a transgenic overexpression approach in order to investigate the inhibitory activity of the PGIP on the PG from Rhizoctonia solani, the causal agent of damping off and root rot of canola. PGIP expression was determined in the functional inhibition assays against fungal PGs. Crude protein extracts prepared from transgenic canola leaves were found to inhibit the R. solani PG from 29% to 37% as compared to untransformed plants. The putative transgenic canola lines harbouring the pgip2 gene encoding polygalacturonase-inhibiting proteins were identified by polymerase chain reaction and Southern blot analysis.