Abstract
This study was conducted to clarify the intra-and interspecific relationships of tetraploid ryegrass cultivars based on the phosphogluco isomerase isozyme (Pgi-2) variation. The leaf materials of 10 tetraploid ryegrass cultivars in the two Lolium species were assayed by the horizontal starch gel electrophoresis for an enzymic system, Pgi-2. The results obtained were as follows. 1. Seven bands were detected on the zymograms of Pgi-2, and 26 phenotypes in the possible 35 phenotypes have been identified by means of the gene dosage effects on the isozyme bands. Besides, four alleles on a locus were confirmed in the tetraploid cultivars. 2. Several different phenotypes were observed in each cultivar. 3. For testing the distinctiveness and the relationships among cultivars in the two species, Nei's genetic distance was applied. As the results, it was suggested that there was distinctive difference of allele frequencies between L. perenne and L. multiflorum. 4. The allele frequencies of the two tetraploid ryegrass species agreed well with those of the diploid ryegrasses reported in the author's previous paper (1985).
