Incompatibility Factors in the Natural Population of Schizophyllum commune

I. Analysis of the Incompatibility Factors Present in Fruit Bodies Collected within a Small Area

Abstract

Fifteen stocks of Schizophyllum commune collected within a circle of 220 meters radius on the campus of Okayama University have been analyzed for the determination of the mating types present. An effort was made to obtain recombinants at the mating type loci by placing the fruit bodies at 34°for a minimum of 18 hours prior to collection of the spores. Details of spore isolation and mating procedures are given. The methods of analysis for determination of mating types are described. Of the 30 parental strains tested there were 24 different A factors and 24 different B factors. A factor recombinants were obtained from nine of the 15 stocks, while only two of the stocks had recombinant B factors. When the parentals were mated with the recombinant strains, there were two recombinants which had A factors identical with the parentals; this indicates that recombinants of the mating type factor become distributed in the natural population. From this sample the estimation of the number of A factors in the natural population is significantly low. It is suggested that this low estimate is due to an unusually high number of identical mating type factors in this sample of 15 stocks which contained six fruit bodies which were located close together, three on one tree trunk and three on another, so that each of these groups of fruit bodies may have arisen from a common dikaryon. The present data are discussed in reference to studies of a somewhat similar nature by others.