Relationships among creeping bentgrass cultivars based on isozyme polymorphisms

An understanding of the genetic variability within a crop species is essential to its improvement. The objectives of this research were to study the utility of isozyme patterns for creeping bentgrass (Agrostis palustris Huds.) cultivar identification and to estimate the relationships between creeping bentgrass cultivars based on isozyme patterns. Seventy to 73 plants from each of 18 creeping bentgrass cultivars and 25 plants from one plant introduction were scored for 24 isozyme polymorphisms representing six loci. All cultivars except a small group containing the cultivars Pennlinks, Pro/Cup, Southshore, and Lopez were uniquely characterized based on a 20% or greater band frequency in one cultivar versus absence of the band in the most closely clustered cultivar. The isozyme patterns from each plant were used to calculate the genetic distance within a cultivar, and the average band frequency within a cultivar was used to calculate genetic distances between cultivars. The cultivars Pennlinks, Pro/Cup, Southshore, and Lopez had the highest average within-cultivar genetic distances indicating that additional marker loci will be needed to distinguish these cultivars. The unweighted pair group method with arithmetic average (UPG, MA) cluster analysis generated from the between-cultivar genetic distance matrix divided the cultivars into two groups. One group contains 10 cultivars including the variety Seaside which may have provided initial germplasm for this group. The second group contains the cultivars Pennlinks, Southshore, Pru/Cup, Lopez, and four cultivars with unique allozymes. The plant introduction PI251945 was distantly related to the cultivated U.S. germplasm indicating that European material can be a source of genetic diversity to broaden U.S. bentgrass germplasm.