The Neurospora crassa pheromone precursor genes are regulated by the mating type locus and the circadian clock

Abstract

Summary Pheromones play important roles in female and male behaviour in the filamentous ascomycete fungi. To begin to explore the role of pheromones in mating, we have identified the genes encoding the sex pheromones of the heterothallic species Neurospora crassa. One gene, expressed exclusively in mat A strains, encodes a polypeptide containing multiple repeats of a putative pheromone sequence bordered by Kex2 processing sites. Strains of the opposite mating type, mat a, express a pheromone precursor gene whose polypeptide contains a C‐terminal CAAX motif predicted to produce a mature pheromone with a C‐terminal carboxy‐methyl isoprenylated cysteine. The predicted sequences of the pheromones are remarkably similar to those encoded by other filamentous ascomycetes. The expression of the pheromone precursor genes is mating type specific and is under the control of the mating type locus. Furthermore, the genes are highly expressed in conidia and under conditions that favour sexual development. Both pheromone precursor genes are also regulated by the endogenous circadian clock in a time‐of‐day‐specific fashion, supporting a role for the clock in mating.

Circadian rhythmicity mediated by temporal regulation of the activity of p38 MAPK

“…However, we believe it is unlikely that the OS pathway controls rhythmicity of all N. crassa ccgs. For example, ccg-7, encoding glyceraldehyde-3-phosphate dehydrogenase, is a morning-specific ccg that is not regulated by osmotic stress (17). Microarray experiments are currently underway to investigate which of the N. crassa ccgs are induced/repressed by osmotic shock and are rendered arrhythmic in a ⌬rrg-1 strain.…”

“…To date, Ͼ180 ccgs have been identified in N. crassa (10)(11)(12)(13)(14), including genes associated with rhythms in asexual spore development (conidiation; ref. 15), metabolism (16), pheromone production (17), and stress responses (18). However, only a handful of these ccgs have been studied in depth, and few details of the output pathways from N. crassa or any other organism's circadian oscillator are known.…”

The Response Regulator RRG-1 Functions Upstream of a Mitogen-activated Protein Kinase Pathway Impacting Asexual Development, Female Fertility, Osmotic Stress, and Fungicide Resistance inNeurospora crassa

“…This shows that RRG-1 regulates poi-2. Other genes affecting Neurospora sexual development, such as the peptide pheromones mfa-1 and ccg-4 (Bobrowicz et al, 2002;Kim and Borkovich, 2006), were expressed at normal levels in ⌬rrg-1 mutants (data not shown). Because nik-1/ os-1 mutants differentiate protoperithecia, whereas strains lacking rrg-1 and the downstream os mutants do not, additional histidine kinase(s) likely regulates RRG-1 to direct protoperithecial development in Neurospora.…”

“…Protoperithecia extend specialized hyphae called trichogynes that are positively chemotropic, growing toward male cells (any vegetative cell type; typically, macroconidia) of opposite mating type (Bistis, 1981). Successful attraction requires that the male cell produces pheromone and that the female contains the appropriate pheromone receptor (Bistis, 1983;Bobrowicz et al, 2002;Kim et al, 2002;Kim and Borkovich, 2004). Once physical contact is established, the trichogyne coils around and fuses with the male cell (Bistis, 1981;Kim and Borkovich, 2004).…”

Complexity of theNeurospora crassaCircadian Clock System: Multiple Loops and Oscillators

“…crassa displays an easily observable 22-hour rhythm in asexual spore development (conidiation) when cultures are grown in constant darkness (DD) , as well as rhythms in gene expression (Loros et al 1989), metabolism (Shinohara et al 1998), pheromone production (Bobrowicz et al 2002), stress response (Shinohara et al 2002), and other processes (for review, see Vitalini et al 2006).…”