Photoresponses in B. cinerea are modulated by the light-responsive transcription factor BcLTF1.
Light determines the mode of asexual reproduction (conidia vs. sclerotia), is required for differentiation of the fruiting bodies (apothecia) and is further considered to set the circadian clock. The cellular redox status is affected by emerging singlet oxygen and other ROS; compensation is achieved by induction of antioxidant systems including enzymes and carotenoids. Bcltf1 represents one of the 244 light-induced genes, and its absence affects several light-dependent features such as the formation of reproductive structures. The deletion of BcLTF1 leads to an unbalanced ROS status (net overproduction of H2O2), possibly in the mitochondria, as suggested by the upregulation of the alternative respiration pathway. The altered ROS status is considered to cause the inability of the deletion mutant to tolerate additional oxidative stress that arises during illumination (singlet oxygen), exposure to ROS (H2O2, menadione) and during host infection (oxidative burst).