Originally published as Genetics Published Articles Ahead of Print on January 12, 2009.

Genetics, Vol. 181, 917-931, March 2009, Copyright © 2009
doi:10.1534/genetics.108.097808

Rhythmic Conidiation in Constant Light in Vivid Mutants of Neurospora crassa

Kevin Schneider*, Sabrina Perrino*, Kim Oelhafen*, Sanshu Li{dagger}, Artiom Zatsepin{dagger}, Patricia Lakin-Thomas{dagger} and Stuart Brody*,1

* Division of Biological Sciences, University of California, San Diego, California 92093-0116 and {dagger} Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada

1 Corresponding author: Division of Biological Sciences (0116), University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0116.
E-mail: sbrody{at}ucsd.edu

In Neurospora crassa, a circadian rhythm of conidiation (asexual spore formation) can be seen on the surface of agar media. This rhythm has a period of 22 hr in constant darkness (D/D). Under constant illumination (L/L), no rhythm is visible and cultures show constant conidiation. However, here we report that strains with a mutation in the vivid (vvd) gene, previously shown to code for the photoreceptor involved in photo-adaptation, exhibit conidiation rhythms in L/L as well as in D/D. The period of the rhythm of vvd strains ranges between 6 and 21 hr in L/L, depending upon the intensity of the light, the carbon source, and the presence of other mutations. Temperature compensation of the period also depends on light intensity. Dark pulses given in L/L shift the phase of the rhythm. Shifts from L/L to D/D show unexpected after effects; i.e., the short period of a vvd strain in L/L gradually lengthens over 2–3 days in D/D. The rhythm in L/L requires the white collar (wc-1) gene, but not the frequency (frq) gene. FRQ protein shows no rhythm in L/L in a vvd strain. The conidiation rhythm in L/L in vvd is therefore driven by a FRQ-less oscillator (FLO).


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Genetics 2009 181: NP. [Full Text]