from Javier Avalos and Luis M. Corrochano writing in Neurospora: Genomics and Molecular Biology:
Neurospora produces a mixture of carotenoid and apocarotenoid pigments, with the orange xanthophyll neurosporaxanthin as the major component. The five genes needed to produce this carboxylic apocarotenoid, in sequential order al-3, al-2, al-1, cao-2 and ylo-1, are known and the encoding enzymes have been biochemically investigated. Neurosporaxanthin biosynthesis is induced by light at the level of transcription through the specific action of the White Collar complex, a photoreceptor and transcription factor. Additionally, the pathway is developmentally induced during conidiogenesis and carotenoids are accumulated in the conidia in the dark. The function of the carotenoids has not been well established, but different observations point to protective roles against sun exposure and oxidative stress.
Further reading: Neurospora: Genomics and Molecular Biology