Are carotenoids the blue-light photoreceptor in the photoinduction of protoperithecia in Neurospora crassa?

A triple albino mutant of Neurospora crassa with a measured content of carotenoids absorbing at 470 nm less than 0.5% of that of the wild type (calculated value less than 8·10(-4)%) had the same threshold for photoinduction of protoperithecia as the wild type when illuminated with monochromatic light at 471 nm. This is strong evidence against the hypothesis that the bulk of carotenoids are the blue-light photoreceptor for this phenomenon. However, it is impossible to exclude traces of carotenoids acting as the photoreceptor at less than 3·10(-12) M in a very efficient sensory transduction chain.