Cyclic Lipopeptides of Bacillus amyloliquefaciens DHA6 Are the Determinants to Suppress Watermelon Fusarium Wilt by Direct Antifungal Activity and Host Defense Modulation

Fusarium wilt, caused by f. sp. ( ), poses a serious threat to watermelon productivity. We previously characterized six antagonistic bacterial strains, including DHA6, capable of suppressing watermelon Fusarium wilt under greenhouse conditions. This study investigates the role of extracellular cycli...

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Published in:Journal of fungi (Basel) 2023-06, Vol.9 (6), p.687
Main Authors: Al-Mutar, Dhabyan Mutar Kareem, Noman, Muhammad, Abduljaleel Alzawar, Noor Salih, Azizullah, Li, Dayong, Song, Fengming
Format: Article
Language:English
Subjects:
Antifungal activity
Antimicrobial agents
Bacillomycin
Bacillus amyloliquefaciens
biocontrol
Crop diseases
Defense mechanisms
extracellular lipopeptides
Fusarium
Fusarium oxysporum f. sp. niveum
Fusarium wilt
induced systemic resistance
Ions
Jasmonic acid
Lipopeptides
Mass spectroscopy
Oxidative stress
Plant diseases
rRNA 16S
Salicylic acid
Seeds
Spore germination
Surfactin
watermelon
Wilt
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Summary:Fusarium wilt, caused by f. sp. ( ), poses a serious threat to watermelon productivity. We previously characterized six antagonistic bacterial strains, including DHA6, capable of suppressing watermelon Fusarium wilt under greenhouse conditions. This study investigates the role of extracellular cyclic lipopeptides (CLPs) produced by strain DHA6 in Fusarium wilt suppression. Taxonomic analysis based on the gene sequence categorized strain DHA6 as . MALDI-TOF mass spectrometry identified five families of CLPs, i.e., iturin, surfactin, bacillomycin, syringfactin, and pumilacidin, in the culture filtrate of DHA6. These CLPs exhibited significant antifungal activity against by inducing oxidative stress and disrupting structural integrity, inhibiting mycelial growth and spore germination. Furthermore, pretreatment with CLPs promoted plant growth and suppressed watermelon Fusarium wilt by activating antioxidant enzymes (e.g., catalase, superoxide dismutase, and peroxidase) and triggering genes involved in salicylic acid and jasmonic acid/ethylene signaling in watermelon plants. These results highlight the critical roles of CLPs as determinants for DHA6 in suppressing Fusarium wilt through direct antifungal activity and modulation of plant defense responses. This study provides a foundation for developing DHA6-based biopesticides, serving as both antimicrobial agents and resistance inducers, to effectively control Fusarium wilt in watermelon and other crops.
ISSN:2309-608X
2309-608X
DOI:10.3390/jof9060687