The Mating-type Systems of the Myxomycetes Physarum rigidum and P. flavicomum

Abstract

SUMMARYThree geographical collections (isolates) of myxomycetes originally identified as PhysarumJlavicomum were found to be heterothallic and the clones established from each isolate were divided into two mating types. Previous studies of six isolates of P.Javicomum showed that they could be divided into three groups. Mating occurred within groups but not between groups, and within each group there were two or more mating types. When the new isolates were crossed to the original isolates, they conformed to two of these three groups. This study established the existence of multiple alleles at the incompatibility locus in group 3. Mating-type alleles of the Fl generation of group 3 segregated in a I : I ratio at meiosis. Isolates belonging to group I were also separated from the other two groups on morphological and physiological bases. The morphological description fits that of P. rigidum more nearly than P. Jlavicomum and group I isolates were placed in the species P. rigidurn. Groups z and 3 were separated genetically and physiologically but morphologically the separation was not distinct. These groups were referred to as P.Jlavicomum varieties I and 2.

Nutritional Requirements for the Growth in Pure Culture of the Myxomycete Physarum rigidum and Related Species

“…The present work was done with the PHILIPPINE 11 isolate while they worked with the AFRICA isolate. These two isolates formed a compatible allelic series (Henney & Henney, 1968).…”

“…Axenic clones (myxamoebae) of the organisms studied were established by the methods previously described (Henney & Henney, 1968). Axenic plasmodia were produced by mixing two compatible clones together on half-strength corn meal agar…”

Studies on the Mating Systems of Eleven Species of Myxomycetes

“…YA question mark after a number indicates that spores from interstrain crosses are non-viable. " Henney (1967). ""Henney (l968)-includes Pliysarum bilgramii.…”

“…Both homoth~llic a?d hete.rothallic isolates have been found in Fuligo septtca, Physarum cinereum, Physarum pusillum, Didymium diiiorme, Didymium iridis, and Didymium~i gripes (see Table 2 for references). Interstenle mating groups have been reported for Physarun: [lavicomum (Henney, 1967), Physarum globuli- ferum , Physarum polycephalum (Collins, 1975a), Physarum pusillum (Collins, Alexopoulos and Henney, 1964), and Physarum rigidum (Henney, 1967;Henney and Henney, 1968). Studies on the DNA content and chromosome numbers have revealed a remarkable amount of variation both between and within strains of the two species which have been well examined: Physarum polycephalum (Ross, 1961(Ross, , 1966Guttes, Guttes and Rusch, 1961;von Stosch, Van Zul-Pischinger and Dersch, 1964;Koevenig and Jackson, 1966;Mohberg andRusch, 1971, Mohberg et al, 1973) and Didymium iridis (Therrien, 1966;Yemma and Therrien, 1972;Therrien and Yemma, 1974).…”

Cytoplasmic inheritance of the selfing factor in the myxomycete Didymium iridis

“…Most notable have been those investigations with Physarum polycephalum (Dee, 1962(Dee, , 1966, Didymium iridis (Collins, 1961(Collins, , 1963(Collins, , 1965Ling, 1964, 1968;Mukherjee and Zabka, 1964), Physarum pusillum (Collins, 1962), Physarumfiavicomum (Henney, 1967;Henney and Henney, 1968) and Physarum rigidum (Henney and Henney, 1968).…”