The constitution of incompatibility factor and mating characteristics of spore isolates in a bipolar mushroom, Pholiota nameko

Abstract

Pholiota nameko is a wood-rotting edible mushroom that carries a bipolar A incompatibility factor gene. The linkage analysis of the multiple allelomorphic A factor gene demonstrated that sexual reproduction produced a monospore isolate carrying a new A factor gene in addition to two parental mating types of isolates. However, 10%-30% of the modified monospore isolates could not produce a dikaryon with both of the parental monokaryons by crossing. It is concluded that the bipolar A incompatibility factor gene of P. nameko is constituted of two functional subunits, Aα and A , which might be successively located beside each other with an apparent genetic distance of 0.3 centi-Morgan between them on the same chromosome. Further, some monospore isolates that did not conjugate with both parental monokaryons could produce dikaryons with different monokaryotic stocks with either one of the parental mating types. This result suggests that the crossing capability of these isolates were essentially those for one of the mating types of the parental monokaryons, but that their function for mating activity was made partially by unequal crossingover in the process of sexual recombination.

A -Mating-Type Gene Expression Can Drive Clamp Formation in the Bipolar Mushroom Pholiota microspora (Pholiota nameko)

“…Although Pholiota microspora (P. nameko, Strophariaceae) has a very similar life cycle to other members of the order Agaricales, such as the tetrapolar mushroom C. cinerea, it has a bipolar A incompatibility factor and at least six different mating types (29). Ratanatragooldacha et al (29) concluded that the bipolar A locus of P. microspora contains two functional subunits, A␣ and A␤, which appear to be located 0.3 centimorgan apart from each other on the same chromosome.…”

“…Ratanatragooldacha et al (29) concluded that the bipolar A locus of P. microspora contains two functional subunits, A␣ and A␤, which appear to be located 0.3 centimorgan apart from each other on the same chromosome. Aimi et al (1) sequenced and characterized the P. microspora genes encoding the homeodomain protein, hox1, and the pheromone receptor, rcb1, which are putative homologues of the HD1 protein and putative pheromone receptor protein genes in the tetrapolar basidiomycete C. cinerea, respectively.…”