Estimating genetic conformity between related ryegrass (Lolium) varieties.1. Morphology and biochemical characterisation

In this study the morphological and protein diversity of twelve diploid per ennial ryegrass accessions (Lolium perenne L.) was examined. These accessio ns comprised five closely related groups, each containing an 'initial varie ty' (IV) and one or more declared 'essentially derived varieties' (EDV), wi th differing degrees of relatedness. 'Essential derivation' is a legal conc ept relating to intellectual property in plant varieties and is additional to Plant Breeders Rights (PBR). An EDV is defined as clearly distinct from, but conforming in its expression of the essential characteristics of an IV , from which it is found to have been predominantly derived. Where an essen tial derivation has been confirmed, the breeder of the IV may be entitled t o some royalty sharing of the EDV. Clearly, therefore, in any successful ED V claim, evidence of a high degree of conformity in either the phenotype or genotype would be required. Examination of plant morphology indicated that all the EDVs were morphologically distinct from their corresponding IV in one or more morphological characteristic. using a principal co-ordinates an alysis to give an overall measure of morphological difference, all twelve a ccessions were correctly clustered into their related groups and the magnit ude of the differences within groups reflected their known breeding histori es. Examining protein diversity by methods that targeted single- and multip le-locus genes also clustered the accessions into their correct groups, in most cases. However, only by examining diversity in seed storage proteins w ere within-group relationships accurately represented. The methods used pro vided no consistent representation of between-group relationships. It was c oncluded that the morphological method provided a creditable measure of gen etic conformity, but to avoid incurring excessive time, work and cost, resu lts from existing national PBR trials would need to be openly available. Wi thin the limits of the genetic material examined, seed storage protein dive rsity appeared to provide a suitable combination of accuracy and efficiency on which to base a routine test. However, given more complex breeding rela tionships than those in this study, methods such as AFLP(1) markers that sa mple more genetic diversity, may be necessary to maintain this level of acc uracy.