Prokaryotic expression and protein function of Brassica napus PGIP2 and its genetic transformation

Sclerotinia rot is a fungal disease caused by Sclerotinia sclerotiorum (Lib.) de Bary, which has severely reduced rapeseed production worldwide. Polygalacturonase-inhibiting proteins (PIGPs) inhibit the activity of polygalacturonases, which are secreted during fungal infection in plants. This study investigated the function of the polygalacturonase-inhibitor gene 2 (PGIP2) in sclerotinia rot resistance. The PGIP2 was successfully expressed in a prokaryotic system, and recombinant PGIP2 protein, purified after enterokinase treatment to remove tag peptide, inhibited S. sclerotiorum PG activity in vitro. PGIP2 was overexpressed in the susceptible Brassica napus cultivar 98c40 via Agrobacterium-mediated transformation. After inoculation with S. sclerotiorum mycelia, the transgenic rapeseed demonstrated greatly reduced leaf damage, as compared with their non-transgenic plants. Therefore, the PGIP2 encodes a functional protein and would be a candidate gene for enhancing Sclerotinia rot resistance.