Novel Multiresistant Osmotin-like Protein from Sweetpotato as a Promising Biofungicide to Control Ceratocystis fimbriata by Destroying Spores through Accumulation of Reactive Oxygen Species

Osmotin-like proteins (OLPs) play an important role in host-plant defense. In this study, a novel multiresistant OLP (IbOLP1) was screened from sweetpotato (Ipomoea batatas) with a molecular weight of 26.3 kDa. The expression level of IbOLP1 was significantly higher in resistant cultivars than susceptible ones after inoculation with Ceratocystis fimbriata, which causes black rot disease in sweetpotato. The expression of IbOLP1 in Pichia pastoris led to the lysis of yeast cells themselves. The recombinant IbOLP1 displayed antifungal, antibacterial, and antinematode activity and stability. IbOLP1 could restrain the mycelial growth and lyse spores of C. fimbriata, distinctly reducing the incidence of black rot in sweetpotato. The IbOLP1 can trigger the apoptosis of black rot spores by elevating the intracellular levels of reactive oxygen species. Collectively, these findings suggest that IbOLP1 can be used to develop natural antimicrobial resources instead of chemical agents and generate new, disease-resistant germplasm.