Fig. 8

Putative mechanism of Zn²⁺ induction of cellulase production in Trichoderma reesei. Supplementation of medium with 3 mM Zn²⁺ enhanced cellulase production and the expression of plc-e and calcium signaling genes. Disruption of plc-e, treatment with LaCl₃ (a plasma membrane Ca²⁺ channel blocker), and the deletion of crz1 (calcineurin-responsive zinc-finger transcription factor 1) revealed that calcium signaling is partially involved in the induction process. Moreover, there were marked reduction in mRNA levels of the zinc-responsive transcription factor zafA in response to Zn²⁺ stimulation. Deletion of zafA indicated that this transcription factor plays a prominent role in mediating Zn²⁺-induced excessive production of cellulase. The solid arrows indicate data supported by our results, and the dashed arrows indicate undefined regulation