Summary Trichoderma arundinaceum (Ta37) and Botrytis cinerea (B05.10) produce the sesquiterpenoids harzianum A (HA) and botrydial (BOT), respectively. TaΔTri5, an HA non‐producer mutant, produces high levels of the polyketide compounds aspinolides (Asp) B and C. We analyzed the role of HA and Asp in the B. cinerea ‐ T. arundinaceum interaction, including changes in BOT production as well as transcriptomic changes of BcBOT gene...

Summary H arzianum A ( HA ), a trichothecene produced by T richoderma arundinaceum , has recently been described to have antagonistic activity against fungal plant pathogens and to induce plant defence genes. In the present work, we have shown that a tri5 gene‐disrupted mutant that lacks HA production overproduces two polyketides, aspinolides B and C , which were not detected in the wild‐type strain. Furthermore, four new aspi...