AUTHOR=Li Peiqian , Feng Baozhen , Yao Zhen , Wei Bohui , Zhao Yanfei , Shi Shouguo 

TITLE=Antifungal Activity of Endophytic Bacillus K1 Against Botrytis cinerea

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.935675

DOI=10.3389/fmicb.2022.935675

ISSN=1664-302X

ABSTRACT=<p>Gray mold caused by <italic>Botrytis cinerea</italic> is detrimental to plants and fruits. Endophytes have been shown to modify plant disease severity in functional assays. We conducted this study to investigate the endophytic strain <italic>Bacillus</italic> K1 with excellently antagonistic <italic>B. cinerea</italic> from the wild grape endosphere. We identified a wild grape endophytic strain K1 with high antifungal activity against <italic>B. cinerea</italic> both <italic>in vitro</italic> and <italic>in vivo</italic>. Combining the phylogenetic results based on 16S rDNA and genome sequencing, K1 was assigned as <italic>Bacillus subtilis</italic>. The <italic>in vitro</italic> results displayed that K1 and its volatile substances could significantly inhibit the mycelia growth of <italic>B. cinerea</italic>. Grape fruit inoculated with <italic>Bacillus</italic> K1 showed lower gray mold during treatment. The higher levels of defense-related enzymes, including peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase, were induced in grapes after inoculation. Scanning electron microscopy (SEM) suggested that K1 inhibited mycelial growth <italic>via</italic> bacterial colonization and antibiosis in grapes. The gas chromatography–mass spectrometry analysis identified 33 volatiles in which dibutyl phthalate was the major compound accounting for 74.28%. Dibutyl phthalate demonstrated strong activity in suppressing the mycelia growth of <italic>B. cinerea</italic>. Genome bioinformatics analysis revealed that the K1 chromosome harbored many known biosynthesis gene clusters encoding subtilosin, bacillaene, bacillibactin, bacilysin, and fengycin. This study provides a potential biological agent to control diseases of post-harvest grape fruit and improves our understanding of the possible biocontrol mechanisms of the <italic>Bacillus</italic> strain.</p>