DEVELOPMENTAL AND PHOTOREGULATION OF 3 NEUROSPORA-CRASSA CAROTENOGENIC GENES DURING CONIDIATION INDUCED BY DESICCATION

Neurospora crassa asexual sporulation (conidiation) is induced by diff erent cues including desiccating aerial environments, Three of the gen es that are expressed during this developmental pathway are the albino (al) genes, which encode carotenoid biosynthetic enzymes, If conidiat ion is induced by nutrient deprivation in liquid culture, two overlapp ing al-3 mRNAs, al-3 (m) and al-3 (c), are expressed (Arpaia et al., 1 995, Dev, Biol, 170, 620-635), Here we quantitate accumulation of each of the four albino gene messages, al-1, al-2, al-3 (m), and al-3 (c), in conidiating wild-type cultures and in cultures of two mutants defe ctive in photoinduced carotenogenesis, wc-1 and wc-2, Of the four albi no gene transcripts, only al-1 expression is developmentally regulated in wild-type cultures conidiating in darkness, Expression of all four albino gene transcripts is developmentally regulated in conidiating w c-1 or wc-2 cultures, Unlike other albino gene transcripts, expression of al-3 (c) is photoregulated only early in conidiation. The fld and fl mutants are defective in conidiation with development halting at di stinct early stages of spore formation, In desiccated fld and fl cultu res al-1, al-2, and al-3 (m) transcript accumulation is observed to pe ak early and then decline, while al-3 (c) transcript accumulation incr eases with time. (C) 1997 Academic Press.