Velvet bentgrass (Agrostis canina L.) is the likely ancestral diploid maternal parent of allotetraploid creeping bentgrass (Agrostis stolonifera L.)

Abstract

Understanding genetic relationships among the three most important Agrostis species will be important in breeding and genomic studies aimed at cultivar improvement. Creeping, colonial, and velvet bentgrasses (Agrostis stolonifera L., A. capillaris L., and A. canina L., respectively) are commercially important turfgrass species often used on golf courses. Velvet bentgrass is a diploid and creeping and colonial bentgrasses are both allotetraploids. A model for the genomic relationships among these species was previously developed from cytological evidence. The genome designations were A1A1 for velvet bentgrass, A1A1A2A2 for colonial bentgrass, and A2A2A3A3 for creeping bentgrass. Here we used phylogenetic analysis based on DNA sequences of nuclear ITS and protein coding genes and the plastid trnK intron and matK gene to reexamine these relationships. In contrast to the previous model, the DNA sequence analysis suggested that velvet bentgrass was closely related to creeping bentgrass and it is likely the maternal parent of creeping bentgrass. Phylogenetic analysis of some conserved nuclear genes revealed a close relationship of the velvet bentgrass sequences with the A2 subgenome sequences of creeping bentgrass. We therefore propose that velvet bentgrass be designated as having the A2 genome, rather than the A1 genome as in the previous model.