| Summary: | <i>Beauveria bassiana</i> is a globally distributed entomopathogenic fungus that produces various secondary metabolites to support its pathogenesis in insects. Two polyketide synthase genes, <i>pks14</i> and <i>pks15</i>, are highly conserved in entomopathogenic fungi and are important for insect virulence. However, understanding of their mechanisms in insect pathogenicity is still limited. Here, we overexpressed these two genes in <i>B. bassiana</i> and compared the metabolite profiles of <i>pks14</i> and <i>pks15</i> overexpression strains to those of their respective knockout strains in culture and in vivo using tandem liquid chromatography-mass spectrometry (LC-MS/MS) with Global Natural Products Social Molecular Networking (GNPS). The <i>pks14</i> and <i>pks15</i> clusters exhibited crosstalk with biosynthetic clusters encoding insect-virulent metabolites, including beauvericins, bassianolide, enniatin A, and the intracellular siderophore ferricrocin under certain conditions. These secondary metabolites were upregulated in the <i>pks14</i>-overexpressing strain in culture and the <i>pks15</i>-overexpressing strain in vivo. These data suggest that <i>pks14</i> and <i>pks15</i>, their proteins or their cluster components might be directly or indirectly associated with key pathways in insect pathogenesis of <i>B. bassiana</i>, particularly those related to secondary metabolism. Information about interactions between the polyketide clusters and other biosynthetic clusters improves scientific understanding about crosstalk among biosynthetic pathways and mechanisms of pathogenesis.
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