Multitrophic antagonistic activity and biocontrol efficacy of volatile organic compounds produced by two Pseudomonas strains against five phytopathogens

초록

Fungal and oomycete pathogens threaten food security and human health via mycotoxin contamination and exacerbating antifungal resistance, necessitating novel control strategies. Therefore, this study aims to investigate the antagonistic activity of two Pseudomonas strains (I-9 and I-22) against five phytopathogens-Aspergillus flavus, Fusarium graminearum, Penicillium italicum, Penicillium expansum, and Phytophthora infestans. The in vitro evaluation showed that I-22 effectively inhibited the growth of A. flavus (18.2 %), F. graminearum (64.2 %), P. italicum (63.2 %), P. expansum (65.6 %), and P. infestans (46.5 %). In contrast, I-9 exhibited lower inhibitory effects on A. flavus (15.9 %), F. graminearum (49.2 %), P. italicum (31.1 %), P. expansum (33.2 %), and P. infestans (40.9 %). Both strains reduced aflatoxin B1 and B2 production and completely inhibited the synthesis of zearalenone, deoxynivalenol, 15-acetyldeoxynivalenol, and ochratoxin A. Volatile organic compounds (VOCs) from I-22 inhibited A. flavus by 84.31 % and F. graminearum by 100 %, while I-9 exhibited lower inhibition. Both strains completely inhibited P. italicum, P. expansum, and P. infestans. In vivo VOC assessments revealed generally lower inhibition. Taxonomic identification showed that strains I-22 and I-9 shared the highest 16S rRNA gene sequence percentage with Pseudomonas koreensis Ps 9-14 T (99.9 %) and Pseudomonas donghuensis HYST (100 %), respectively. Both strains produced hydrocyanic acid, while siderophore production was detected only in I-9. Both strains produced lipopeptides, but only those from strain I-22 exhibited inhibitory activity, specifically against P. italicum. VOCs were analyzed via SPME-GC/MS, revealing dimethyl disulfide as a predominant compound in both strains. These findings highlight their potential as promising biological alternatives for postharvest disease management.

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