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The Global Secondary Metabolite Regulator AcLaeA Modulates Aspergillus carbonarius Virulence, Ochratoxin Biosynthesis, and the Mode of Action of Biopesticides and Essential Oils

Summary

Grapes can be infected with a fungus called Aspergillus carbonarius that produces a dangerous toxin called ochratoxin A. Scientists studied a regulatory gene called AcLaeA that controls toxin production in this fungus. By deleting this gene, the fungus became less virulent and produced much less toxin. Natural products like cinnamon and thyme oils, along with commercial biocontrol products, were found to reduce toxin production by suppressing this regulatory gene, offering promising natural alternatives to chemical fungicides.

Background

Aspergillus carbonarius is a major fungal pathogen causing black and sour rot in grapes and produces ochratoxin A (OTA), a carcinogenic mycotoxin. The LaeA protein is a global regulatory methyltransferase controlling secondary metabolite production in Aspergillus species. Understanding the role of AcLaeA in A. carbonarius pathogenicity and OTA production is essential for developing effective control strategies.

Objective

To investigate the role of the regulatory gene AcLaeA in A. carbonarius physiology, virulence, and ochratoxin A production by deleting this gene from the genome. Additionally, to evaluate whether commercial biopesticides and essential oils inhibit OTA biosynthesis through repression of AcLaeA expression.

Results

ΔAcLaeA mutants showed significantly reduced growth, conidial production (40-50% reduction in grapes), and OTA biosynthesis (99% reduction). Three biopesticides (Trianum-P®, Vacciplant®, Serenade® Max) repressed AcLaeA expression by 5-38 fold. Essential oils of cinnamon, thyme, and geranium effectively reduced mycelial growth and OTA production through AcLaeA downregulation.

Conclusion

AcLaeA plays a key role in A. carbonarius virulence and OTA production. Biopesticides and essential oils (particularly cinnamon, thyme, and geranium) show promise in controlling this mycotoxigenic fungus through AcLaeA modulation. These findings could lead to optimized biocontrol strategies and natural alternatives to synthetic fungicides for preventing OTA contamination in grapes and wine products.
  • Published in:Toxins (Basel),
  • Study Type:Experimental Study,
  • Source: 39852955
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