Meyerozyma guilliermondii SQUCC-33Y suppresses postharvest fruit rot of strawberry caused by Alternaria alternata

Strawberry fruits are vulnerable to infection by a broad range of fungal pathogens before and after harvest. In this study, Alternaria spp. strains associated with fruit rot of strawberry were isolated and characterized and the potential of the antagonistic yeast Meyerozyma guilliermondii strain SQUCC-33Y for the control of fruit rot of strawberry was evaluated. A total of seven isolates of Alternaria (STR2-STR8) were isolated from strawberry fruits showing symptoms of rot. On the basis of internal transcribed spacer (ITS) ribosomal RNA (rRNA) sequences, these fungal isolates were identified as Alternaria alternata. Pathogenicity tests revealed that most of the strains of A. alternata were pathogenic to strawberry. The measurement of disease severity on strawberry fruits revealed significant differences in the virulence between A. alternata strains. M. guilliermondii restricted the growth of all the strains of A. alternata in dual culture assay. Postharvest treatment of strawberry fruits with M. guilliermondii significantly reduced the fruit rot lesion size caused by A. alternata. This antagonistic yeast has the potential for use as a biofungicide for the control of A. alternata-induced postharvest fruit rot of strawberry.