Developmental and photoregulation of al-1 and al-2, structural genes for two enzymes essential for carotenoid biosynthesis in Neurospora.

The levels of al-1 and al-2 transcripts change dramatically in response to light and development during the formation of Neurospora crassa asexual spores (conidia). al-1 and al-2 mRNAs accumulate throughout conidiation irrespective of lighting conditions initially at low levels. As conidiation proceeds, two increases in albino message accumulation are observed. This developmentally induced photoindependent message accumulation was not observed in Neurospora mutants blocked at relevant stages of conidiation. During conidiation, light induces additional accumulation of al-1 and al-2 gene-specific transcripts; the photoinduced increase in albino gene transcript levels was not observed in two Neurospora mutants, wc-1 and wc-2, that are defective in all physiological photoresponses.