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

<i>Aspergillus carbonarius</i> is considered one of the main fungi responsible for black and sour rot in grapes, as well as the production of the carcinogenic mycotoxin ochratoxin A. The global regulatory methyltransferase protein <i>LaeA</i> controls the production of various secondary metabolites in <i>Aspergillus</i> species, as well as influences sexual and asexual reproduction and morphology. The goal of this study was to investigate the role of the regulatory gene <i>AclaeA</i> in physiology, virulence, and ochratoxin A (OTA) production by deleting this gene from the genome of a wild-type <i>A. carbonarius</i> strain. The evaluation data on the morphological characteristics, virulence experiments in three different grape varieties, and OTA analysis of Δ<i>AclaeA</i> mutants showed that the growth and the OTA production by Δ<i>AclaeA</i> strains were significantly reduced. The mutant strains were also less virulent, producing 40-50% less conidia in three different cultivars of grape berries. Additionally, the gene <i>AclaeA</i> was considerably repressed after the application of three commercial biopesticides (Trianum-P^®, Vacciplant^®, and Serenade^® Max) and the essential oils (EOs) cinnamon, geranium, and thyme, which were also shown to inhibit OTA biosynthesis in <i>A. carbonarius</i>. The study of the regulatory gene <i>AclaeA</i> can contribute to a broader understanding of the role of secondary metabolites during <i>A. carbonarius</i>-grape interactions, as well as the discovery of the mode of action of biological plant protection products and EOs against this mycotoxigenic fungus.