Transcriptomic and Exometabolomic Profiling Reveals Antagonistic and Defensive Modes of Action Against .

The mycoparasite ACM941 is under development as a biocontrol organism against , the causative agent of Fusarium head blight in cereals. To identify molecular factors associated with this interaction, the transcriptomic and exometabolomic profiles of and GZ3639 were compared during coculture. Prior to physical contact, the antagonistic activity of correlated with a response heavily dominated by upregulation of polyketide synthase gene clusters, consistent with the detected accumulation of corresponding secondary metabolite products. Similarly, prior to contact, trichothecene gene clusters were upregulated in , while those responsible for fusarielin and fusarin biosynthesis were downregulated, correlating with an accumulation of trichothecene products in the interaction zone over time. A concomitant increase in 15-acetyl deoxynivalenol-3-glucoside in the interaction zone was also detected, with established as the source of this detoxified mycotoxin. After hyphal contact, was found to predominantly transcribe genes encoding cell wall-degradation enzymes, major facilitator superfamily sugar transporters, anion:cation symporters, as well as alternative carbon source utilization pathways, together indicative of a transition to necrotropism at this stage. notably activated the transcription of phosphate starvation pathway signature genes at this time. Overall, a number of signature molecular mechanisms likely contributing to antagonistic activity by against , as well as its mycotoxin tolerance, are identified in this report, yielding several new testable hypotheses toward understanding the basis of as a biocontrol agent for continued agronomic development and application.