Stability of esterases and total proteins during seed storage of perennial ryegrass (Lolium perenne L.) and their use for cultivar discrimination

Abstract

Polymorphisms in electrophoretic patterns obtained by isoelectric focusing (IEF) were examined to evaluate their suitability for cultivar identification in perennial ryegrass (Lolium perenne L.). It was possible to discriminate 64 (94%) of 68 cultivars by combining results from esterase and total protein analysis. Discrimination was based on quantitative differences (relative band intensity) rather than on qualitative differences (presence or absence of bands). Esterase patterns from different recent (fresh to seven years old) seed lots of the same perennial ryegrass cultivars were very stable. Occasionally, minor differences in band intensity were observed between recent and old (up to 30 years old) seed lots of a cultivar. Storage of meal samples up to two years at −20 °C had no effect on the total protein patterns. No correlation was found between esterase patterns and ploidy level, cultivar type (pasture or turf), heading date or breeding company. Esterase patterns appeared to be unsuitable markers for the selection of reference cultivars for distinctiveness, uniformity, and stability (DUS) testing, because no correlation was found between cultivars on the basis of esterase banding patterns and morphological characteristics.