[Biocontrol potential of Talaromyces purpurogenus and its regulation on soil microbial community]

Talaromyces purpurogenus strain Q2 is a kind of beneficial microbe originally separated from the rhizosphere of healthy cucumber. In this study, we evaluated the biocontrol potential of strain Q2 against four soil-borne diseases by plate confrontation culture, potting in the greenhouse. We further estimated the control efficacy of strain Q2 combined metam-sodium fumigation against Fusarium wilt of bitter gourd in the field. The mechanism of strain Q2 controlling bitter gourd wilt and regulating soil microbial community was examined by plate dilution culture, high throughput sequencing and quantitative PCR. The results showed that strain Q2 could efficiently reduce disease incidence of Fusarium wilt of bitter gourd, potato stem canker, black shank of tobacco and black root rot of tobacco in the green house. Its biocontrol efficacy on black shank of tobacco and bitter gourd wilt was 75.3% and 63.4%, respectively. Biocontrol efficacy of strain Q2 on bitter gourd wilt was 51.0% in the artificial disease nursery inoculated pathogen of bitter gourd wilt, while the control efficacy of strain Q2 combined with soil fumigation technology was more than 80% in the same experiment condition. Strain Q2 application and soil fumigation altered soil microbial community composition and recovery trend. Metam-sodium fumigation significantly reduced the abundances of Fusarium oxysporum and causal agent of bitter gourd wilt. Strain Q2 further suppressed the efficient recovery trend of the pathogen. After application of strain Q2, Penicillium was enriched in soil, as well as the beneficial microbes involved in the suppression of F. oxysporum, such as Bacillus and Gaiella. Overall, after soil fumigation, biocontrol efficacy of strain Q2 on soil-borne diseases such as Fusarium wilt could attribute to the formation of beneficial microbial communities in soil and inhibition of strain Q2 on growth and development of F. oxysporum.