Bifactorial incompatibility in the two-spored basidiomycetes Coprinus sassii and C. Bilanatus

Comparative Sexuality in Agaricus Species

“…Two-sporedness is generally seen as a short-term device to limit outbreeding (Koltin, Stamberg & Lemke, 1972). Its evolutionary significance has been considered by Kemp (1974) who suggested that it could be a factor in speciation and that two-spored species, although probably derived from four-spored species, might evolve to give new four-spored species.…”

Genetics of secondarily homothallic basidiomycetes

“…Since the mechanism has been described in only this one species, its general applicability to secondarily homothallic basidiomycetes is not known. Kemp (1974) believes that non-random alignment is the basic mechanism of secondary homothallism and that it functions in a way analogous to the interchange ring complexes of Oenothera, promoting heteroallelism for all loci which segregate at the first division. He sees non-random alignment maintaining particular heteroallelic gene combinations as being important in the development of twospored species from four-spored species and in their reversion back to four-spored forms.…”

“…The largest class consists of doubly heteroallelic spores (AB/ab and Ab/aB) and the other four classes of doubly homoallelic spores (AB/AB, ab/ab, Ab/Ab, and aB/aB). Potentially fertile strains will thus predominate both in unifactorial species (single mating-type factor) and in bifactorial species (two mating-type factors) such as Coprinus sassii (Kemp, 1974). All spores heteroallelic for mating-type will also be heteroallelic for a gene affecting a sporophore character.…”

Gene segregation in the two-spored basidiomycete Coprinus bilanatus

“…prov. was chosen for the study of gene segregation in a 2-spored basidiomycete because its mycelia grow well and fruit in culture and it has bifactorial incompatibility with clamp-connexions (Kemp, 1974). This is the system of homogenic incompatibility found in C. (Kemp, 1975).…”

“…This species has since been found to have bifactorial incompatibility with clamp connexions (Kemp, 1974). Sass noted that the spindles of the second meiotic division were obliquely placed in the basidium and suggested that the formation of dikaryotic spores might be due to the changed orientation of the second meiotic spindles.…”