Effectiveness of a Novel Endophyte Bacillus velezensis Strain B1 in the Biocontrol of Pear Postharvest Ring Rot

Abstract

Pear ring rot caused by Botryosphaeria dothidea severely affects the quality and storage life of pear fruit. Plant endophytes are potential new sources of biocontrol agents due to their abilities to produce novel bioactive products. In this work, we focused on an endophytic strain B1, which was isolated from roots of Dendrobium huoshanense. Notably, strain B1 exhibited strongly inhibitory effects against the growth of Botryosphaeria dothidea with an inhibition rate of 73.2% after 1 week of co-cultivation. Furthermore, it displayed a broad-spectrum inhibitory activity. Strain B1 also effectively delayed the onset of ring rot caused by B. dothidea in pear fruit and reduced the lesion diameter by 73.4%. Strain B1 was identified as Bacillus velezensis based on core-genome phylogeny. Genome mining with antiSMASH revealed 13 potential gene clusters involved in antimicrobial metabolites. Three main groups of lipopeptides (surfactin, iturin and fengycin) were identified with MALDI-TOF-MS, and the lipopeptides in the inhibition zone were greatly upregulated by B. dothidea; especially, fengycin isoforms were detected with higher abundance. These results proved that lipopeptides produced by strain B1 had significant antagonistic effect on B. dothidea. In conclusion, our results suggest that strain B1 has potential applications in the biocontrol of B. dothidea in postharvest fruit.