Overexpression of erg1 gene in Trichoderma harzianum CECT 2413: effect on the induction of tomato defence‐related genes

AIMS: To investigate the effect of the overexpression of erg1 gene of Trichoderma harzianum CECT 2413 (T34) on the Trichoderma–plant interactions and in the biocontrol ability of this fungus. METHODS AND RESULTS: Transformants of T34 strain overexpressing erg1 gene did not show effect on the ergosterol level, although a drastic decrease in the squalene level was observed in the transformants at 96 h of growth. During interaction with plants, the erg1 overexpression resulted in a reduction of the priming ability of several tomato defence‐related genes belonging to the salicylate pathway, and also of the TomLoxA gene, which is related to the jasmonate pathway. Interestingly, other jasmonate‐related genes, such as PINI and PINII, were slightly induced. The erg1 overexpressed transformants also showed a reduced ability to colonize tomato roots. CONCLUSIONS: The ergosterol biosynthetic pathway might play an important role in regulating Trichoderma–plant interactions, although this role does not seem to be restricted to the final product; instead, other intermediates such as squalene, whose role in the Trichoderma–plant interaction has not been characterized, would also play an important role. SIGNIFICANCE AND IMPACT OF THE STUDY: The functional analysis of genes involved in the synthesis of ergosterol could provide additional strategies to improve the ability of biocontrol of the Trichoderma strains and their interaction with plants.