Mutation and divergence of the phospholipase C gene in Neurospora crassa

In the fungus Neurospora crassa we have used RIP to obtain a presumptive null mutation of the phospholipase C-1 gene, thought to be important in intracellular calcium signaling, notably maintenance of the tip-high calcium gradient. The mutant is viable but has slow, aberrant growth and branching. Hence plc-1 is not required for polar growth at the tip, but is necessary to modulate growth to give normal form. The mutant has residual PLC activity suggesting that this enzyme function can be provided from other parts of the genome. Sequencing natural isolates has shown that the plc-1 gene is highly variable in nature. A large proportion of the variable sites are in a region that is unique to Neurospora. A phylogeny for this gene shows that New and Old World strains have diverged the most. Within the Americas, morphs are found throughout the continent suggesting extensive strain dispersal.