Assesing the Abundance and Polymorphism of Simple Sequence Repeats in Perennial Ryegrass

Simple sequence repeats (SSRs) have proven to be useful genetic markers in a wide variety of plants, but have yet to be widely applied to turfgrasses. Here we describe a study of SSRs in perennial ryegrass (Lolium perenne L.). A library of perennial ryegrass genomic DNA was screened with (GA). and (GT). probes, and SSR‐containing clones were isolated and sequenced. On the basis of this screen, we estimated that there are roughly 5800 (GA)n, and (GT)n. SSRs in haploid perennial ryegrass genome. Polymerase chain reaction (PCR) primers were designed to amplify the isolated SSRs, and six polymorphic $SRs were identified. Polymorphism in the these six SSRs was sufficient to discriminate among 18 individuals representing I1 perennial ryegrass clones and seven other Lolium species. Half‐sibs could be distinguished with data from as few as three SSRs. The SSR genotype data was also used to infer genetic relationships among the individuals of our sample. The relationships were in broad agreement with those established by previous analyses, suggesting that SSR data will be usefni for exploring relationships among perennial ryegrass cultivars. In total, this study indicates that SSRs are sufficiently abundant and sufficiently polymorphic to be useful genetic markers in perennial ryegrass.