Tissue-Specific Repression of Starvation and Stress Responses of theNeurospora crassa con-10Gene Is Mediated by RCO1

TheNeurospora crassa con-10gene is weakly expressed in mycelia but is induced approximately 1000-fold during macroconidiation. Studies of the promoter elements andtrans-acting factors that regulatecon-10expression are needed to gain a detailed understanding of developmental regulation. Therco-1mutant displays a 10-fold elevated basal level of expression ofcon-10.In contrast to the wild type,con-10expression in mycelia of therco-1mutant was rapidly induced to high levels by starvation for carbon or nitrogen and by heat shock. Althoughcon-10is developmentally induced late in conidiation,con-10was inducible by heat shock shortly after exposure of the wild-type mycelium to air. These findings support the view that RCO1 is a cell type-specific repressor ofcon-10.We propose that inactivation of RCO1 allows developing conidiophores to adjust the timing ofcon-10induction in response to stress.