Quantifying the proportion of perennial ryegrass cultivars in intra-species mixtures using simple sequence repeat (SSR) and inter-SSR (ISSR) markers and discriminant analysis

Abstract

Perennial ryegrass (Lolium perenne L.) can be sown as a mixture of cultivars, but different ecophysiological mechanisms among cultivars can cause the cultivar proportions to change over time. The objectives of this work were to differentiate the cultivars 'Barnhem', 'Barmaco', 'Barlet' and 'Mara', and to identify their proportions in mixture. Two seed-lots of each cultivar were characterised using one simple sequence repeat (SSR) and two inter-SSR (ISSR) markers. Simulated mixtures based on random sub-samples from monocultures of each cultivar showed that individuals could be correctly allocated to their respective seed-lot and cultivar with 7887% accuracy using discriminant analysis. 100 BG34 plants were collected from three dairy pastures in Ohio, USA and their SSR/ISSR profiles were compared with the reference populations. One pasture had a similar cultivar proportion as the original sown mixture. Two pastures had increased proportions of 'Mara' and 'Barmaco' and decreases of 'Barlet' or 'Barnhem', depending on the pasture. © 2010 The Royal Society of New Zealand.