Abstract
Sequence information from genomic clones containing SSR-motifs was used to design primer pairs for the amplification of SSR-based DNA markers. The markers were screened to distinguish between perennial ryegrass and Italian ryegrass. From a total of 24 primer pairs, nine fragments, amplified by six primer pairs, were identified as species-distinguishable markers. Six of these fragments were assessed for their frequencies in each of : perennial ryegrass, Italian ryegrass and hybrid rygrass. Significant differences in the frequencies of each fragment were observed between perennial ryegrass and Italian ryegrass. In hybrid ryegrass, the frequency of individuals having both perennial ryegrass and Italian ryegrass-specific DNA fragments was high. A high frequency of hybrid ryegrass individuals had both perenial ryegrass-specific nuclear DNA fragments and Itarian ryegrass-specific chloroplast DNA fragments. Cluster analysis revealed that hybrid ryegrass varieties could be separated into two clusters. We conclude that these markers would be suitable to distinguish between perennial ryegrass and Italian ryegrass, and to detect hybridization in a population of ryegrass.
