Genetic Variation within and among Wildrye (Elymus canadensis and E. virginicus) Populations from the Southern Great Plains

There is interest in Canada wildrye (CWR, Elymus canadensis L.) and Virginia wildrye (VWR, E. virginicus L.) for conservation and forage uses. Our objectives were to identify a set of molecular markers to assess genetic structure within and diversity among populations of CWR and VWR from the Southern Great Plains and to determine if these populations had an associated fungal endophyte. Nine CWR and five VWR populations and two barley (Hordeum vulgare L.) cultivars were genotyped using simple sequence repeat (SSR) markers isolated from tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] expressed sequence tags (TF ESTs). Scorable fragments were produced by 31% of TF EST-SSRs tested, thus identifying a set of SSR markers for wildrye. Populations grouped into three clusters consisting of (i) three wild populations, one plant introduction, and two commercial sources of CWR; (ii) all VWR populations and three CWR plant introductions; and (iii) barley cultivars. Clustering indicated possible gene flow between CWR and VWR. Genetic variation within populations was minimal and comparable to that of the barley cultivars. Thus, unlike many ancestral cultivars and landraces of self-pollinated crops, CWR and VWR populations consisted of essentially pure lines and can be handled as such in a breeding program. Potentially sexual and asexual epichloe endophytes were found in several populations, indicating the need to account for endophytes in breeding and germ-plasm conservation efforts of wildrye.