Sexuality and Life-cycle of the Edible, Wild Agaricus bitorquis

Abstract

Five collections from nature, originally identified as representing the 3 spp. A. campestris, A. edulis and A. bitorquis, were shown to be interfertile and are therefore designated A. bitorquis (Quelet) Saccardo. All stocks can be fruited, and analysis of the life-cycle revealed heterothallism with sexuality controlled by a single incompatibility locus with multiple alleles: monosporous siblings are self-sterile and cross-fertile in a bipolar pattern. The fertile interaction in compatible matings is morphologically distinguishable in the formation of a differentiated dikaryotic mycelium without the clamp connexions common in the dikaryons of other Hymenomycetes. The segregation pattern of incompatibility alleles and nutritional markers indicates haploidy of vegetative nuclei. Six parental and 4 rare, non-parental incompatibility types were identified in the sample studied. Heterokaryotic interactions.sbd.dikaryons with homokaryons and dikaryons with dikaryons to establish new dikaryons.sbd.were shown to occur. A remote kinship to the cultivated mushroom was demonstrated in the formation of transitory heterokaryons between A. bitorquis and A. bisporus, but these could not be fruited. The life-cycles and patterns of sexuality in the 2 spp. are compared and the possibility that A. bitorquis could be an alternative to A. bisporus for mass cultivation and consumption, with emphasis on the advantage in breeding A. bitorquis, is mentioned.