Biocontrol of black rot of sweetpotato by Pichia pastoris recombinant strain expressing chitinase IbChiA

Black rot disease, caused by Ceratocystis fimbriata, is highly destructive to sweetpotato (Ipomoea batatas). IbChiA is a chitinase identified from sweetpotato with strong antifungal activity against C. fimbriata. The recombinant yeast X33/pGAPZ alpha A-IbChiA was obtained by transforming IbChiA into Pichia pastoris using the constitutive secretory expression vector pGAPZ alpha A. IbChiA was stably expressed and secreted into the extracellular space without an inducer. The recombinant yeast X33/pGAPZ alpha A-IbChiA could not only distinctly inhibit the conidium germination and mycelial growth of C. fimbriata, but also exhibit excellent colonization ability on the tuberous root wounds of sweetpotato. Biocontrol experiments further revealed that recombinant yeast X33/pGAPZ alpha AIbChiA could effectively limit the expansion of lesions and reduce the severity of black rot in sweetpotato. The findings present a novel approach for the biological control of black rot disease in postharvest sweetpotato.