The Putative Methyltransferase Tl LAE1 Is Involved in the Regulation of Peptaibols Production in the Biocontrol Fungus Trichoderma longibrachiatum SMF2

The biocontrol fungusTrichoderma longibrachiatumSMF2 secretes a large quantity of peptaibols that have been shown to have a range of biological activities and therefore great application values. However, the mechanism of the regulatory expression of peptaibols is still unclear. The putative methyltransferase LaeA/LAE1 is a global regulator involved in the biosynthesis of some secondary metabolites in filamentous fungi. In this study, we demonstrated that the ortholog of LaeA/LAE1 in the biocontrol fungusT. longibrachiatumSMF2,TlLAE1, plays an important role in the regulation of peptaibols production. Deletion ofTllae1resulted in a slight negative impact on mycelial growth, and a significant defect in conidial production. Deletion ofTllae1also compromised the production of peptaibols to a large degree. Further analyses indicated that this defect occurred at the transcriptional level of the two synthetases-encoding genes,tlx1andtlx2, which are responsible for peptaibols production. By contrast, constitutive expression ofTllae1inT. longibrachiatumSMF2 led to 2-fold increased peptaibols production, suggesting that this is a strategy to improve peptaibols production inTrichodermafungi. These results demonstrate the important role of LAE1 in the regulation of peptaibols production inT. longibrachiatumSMF2.