Genetic variation in cultivars of diploid ryegrass,Lolium perenne andL. multiflorum, at five enzyme systems

Samples of .apprx. 100 plants from each of 22 populations of L. perenne representing 15 cultivars, and from 13 populations of L. multiflorum representing 6 cultivars were scored for isozyme variants in 5 enzyme systems: PGI, GOT, ACP, PGM and 6-PGD [phosphoglucoisomerase, glutamate oxaloacetate transaminase, acid phosphatase, phosphoglucomutase, 6-phosphogluconate dehydrogenase]. From the individual banding patterns a genetic interpretation of the variation was formulated and population studies of the resulting 6 polymorphic enzyme loci were performed. No strong indications of partial selfing was found since at 4 of the 6 loci, Pgi 2, Got 3, Pgm 1 and Pgd 1, the genotypic proportions were in correspondence with the Hardy-Weinberg expectations. This indicated, further, that the genetical interpretations of the banding patterns might be correct. Deviations from Hardy-Weinberg proportions for Acp 1 and Got 2 indicated presumably selection working on the linkage group including these loci. Gametic phase disequilibrium was observed between Pgi 2 and Pgd 1 for populations of 1 cultivar. These results were discussed in relation to the variation expected within a cultivar.