Cross-talk between light and glucose regulation controls toxin production and morphogenesis in Aspergillus nidulans

Light is a major environmental stimulus that has a broad effect on organisms triggering a cellular response that results in an optimal adaptation enhancing fitness and survival In fungi light affects growth and causes diverse morphological changes such as those leading to reproduction Light can also affect fungal metabolism including the biosynthesis of natural products In this study we show that in Aspergillus nidulans the effect of light on the production of the sterigmatocystm (ST) toxin depends on the glucose concentration In cultures grown with 1% glucose and exposed to light ST production was lower than when grown in the dark This lower ST production coincided with an elevated rate of cellular damage with partial loss of nuclear integrity and vacuolated cytoplasm However in cultures grown with 2% glucose these effects were reversed and light enhanced ST production Glucose abundance also affected the light-dependent subcellular localization of the VeA (velvet) protein a key regulator necessary for normal light-dependent morphogenesis and secondary metabolism in Aspergilli and other fungal genera The role of other VeA-associated proteins particularly the blue-light-sensing proteins LreA and LreB (WC 1 and WC-2 orthologs) on conidiation could also be modified by the abundance of glucose We also show that LreA and LreB as well as the phytochrome FphA modulate not only the synthesis of sterigmatocystin but also the production of the antibiotic penicillin Published by Elsevier Inc