The inhibitory effect of Xenorhabdus nematophilus on Botrytis cinerea

Abstract:

[Background] Botrytis cinerea is one of the main pathogenic of grapes during postharvest, which seriously affects the storage period and quality of grapes and brings great losses to its industry. The use of antagonistic microorganisms to inhibit the growth of postharvest pathogens has gradually become an important method for the prevention and control of postharvest gray mold in grapes. [Objective] In order to provide new materials and research direction for the inhibition of Botrytis cinerea postharvest. Using the broad-spectrum and efficient antibacterial characteristics of entomopathogenic nematode symbiotic bacteria and screening high antagonistic effect on Botrytis cinerea from the symbiotic bacteria resources. [Methods] Antagonistic symbiotic bacteria were isolated and screened by plate confrontation culture method and mycelial growth rate method, and antagonistic symbiotic bacteria with highly effective, its 16S rRNA gene phylogeny analysis was carried out. The effect of antagonistic symbiotic bacteria on mycelial growth of Botrytis cinerea was studied by scanning electron microscope, and the control effect on Red Globe grape was verified by damage inoculation method. [Results] Nine strains had antagonistion were isolated from 14 bacteria, that one of symbiotic bacteria (ALL) was obtained through rescreening and retesting with significant antibacterial effect. According to phylogeny analysis, it clustered in the same branch with strain Xenorhabdus nematophila NC116 and 99.79% homology, which was identified to Xenorhabdus nematophila (Genbank accession number:MW488402). The strain caused the Botrytis cinerea hyphae to distort, shrink and collapse by scanning electron microscopy observation. The inhibition rate of the growth of Botrytis cinerea hyphae reached 44.5%, When the supernatant concentration was 1% in medium after fermentation (36 h). Compared with the control group, the fermentation supernatant of strain ALL had a better control effect on Botrytis cinerea, and the control effect was 63.50% after 3 days at room temperature. [Conclusion] In this study, we used entomopathogenic nematode symbiotic bacteria to inhibit Botrytis cinerea for the first time during grapes storage, and one of entomopathogenic nematode symbiotic bacteria was screened with high efficiency against Botrytis cinerea, and its supernatant had good inhibitory effect on Botrytis cinerea. The research provided a new biomaterial and related basis for bio-control of Botrytis cinerea during grapes storage.