The data from this study demonstrates for the first time that Neurospora crassa, a circadian
model organism, has a photoperiodic clock. The experiments provide the opportunity
for further research on photoperiodism. Evidence of this study supports the
external coincidence hypothesis that photoperiodism shares the same mechanism with
circadian rhythms. The central components of the Neurospora circadian clock, such
as FRQ and WC-1, are also essential for photoperiodic responses. The dissociation
between frq RNA and FRQ protein in different photoperiods suggests that the transcriptional/
translational regulation is far complicated. The shift of the maximum of
conidial production compared to protoperithecia development suggests the different
favourite season for the asexual and sexual reproduction of Neurospora crassa.
However, there is a difference between circadian rhythm and photoperiodism --
circadian rhythm is endogenous, which remains at constant conditions (DD or LL); in
contrast, photoperiodism requires external signals – light and darkness.
Further research on photoperiodism of Neurospora must be carried out to study
the gene(s) which is/are critical for photoperiodic responses, the molecular mechanism
of transcriptional/translational regulation of critical clock components in photoperiods,
the generation of the oscillator, and the mechanism which differentiates
many outputs of photoperiodic responses.