Abstract:
Objective To screen for efficient biocontrol strains in response to the frequent occurrence of crop diseases and development of pathogen resistance resulting from chemical control.
Method In this study, a biocontrol strain GD1 was isolated from tobacco rhizosphere soil. Its taxonomic status was determined through morphological, physiological, and biochemical analyses, as well as 16S rDNA phylogenetic analysis. The in vitro antagonistic activity of the strain against pathogenic fungi was measured, and the control efficacy of its fermentation broth against citrus anthracnose, citrus blue mold, and tomato gray mold was evaluated.
Result The strain was identified as Paenibacillus taohuashanense. In vitro antagonistic tests showed that strain GD1 exhibited good inhibitory effects against 18 pathogenic fungi, including Penicillium italicum, Botrytis cinerea, Alternaria alternata, Rhizoctonia solani, and Colletotrichum gloeosporioides, with inhibition rates ranging from 30.10% to 88.00%. Ex vivo fruit tests showed that the fermentation broth of GD1 achieved control efficacies of 66.67%, 94.96%, and 66.35% against citrus anthracnose, citrus blue mold, and tomato gray mold, respectively. Genomic sequencing predicted two high-confidence biosynthetic gene clusters encoding the antimicrobial compounds icosalide A/icosalide B (cyclic lipopeptides) and paeninodin (a lasso peptide).
Conclusion In this study, a biocontrol strain with broad-spectrum antifungal activity was obtained, providing a new microbial resource for the biological control of diseases.
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