Figure 4. Over-expression of mtfA suppresses aflR and stcU expression and ST production.

A) Northern blot analysis of aflR and stcU expression. Wild-type isogenic control (WT) veA+ (TRV50.1) and over-expression (OE) mtfA strain (TRV60) were inoculated in GMM liquid medium (10⁶ conidia mL⁻¹) and grown for 16 hrs in a shaker incubator at 37°C and 250 rpm. Then, equal amounts of mycelium were transferred and spread onto TMM agar medium. The cultures were further grown for 48 h and 72 h. Mycelial samples were collected at 0 hr (shift time), and 24 and 48 hrs of incubation after shift onto TMM. 18S rRNA serves as loading control. B) qRT-PCR expression analysis of mtfA from mycelial samples collected after 24 h and 48 h of incubation after transfer onto TMM agar medium. C) TLC analysis of ST production from cultures described in (A-B).