Case studies for the use of infraspecific classifications in managing gerniplasin collections of cultivated plants

Rational categories of infraspecific diversity are useful for structuring a genebank collection, when discussing gene-erosion and for making management decisions for maintenance of ex-situ germplasm collections. The interrelated history of ex-situ germplasm collections and the concept of infraspecific classifications in cultivated plants are briefly outlined. The diversity of oat (Avena sativa), flax (Linum usitatissimum) and coriander (Coriandrum sativum) are considered for discussing their infraspecific diversity as reflected by taxonomy and nomenclature. Phenotypic diversity as evident from characterization data generated at the national genebanks in Canada and Germany and the most significant taxonomic literature for these species form the basis of this discussion. The rationals for distinguishing three subspecies of Avena sativa, four convarieties of Linum usitatissimum and three subspecies of Coriandrum sativum are discussed. The goal of this paper is to demonstrate the usefulness and the limitations of formal infraspecific groupings from a genebank perspective. It is suggested that infraspecific classifications should be complementary and the highest infraspecific ranks should divide the species into the most relevant groups from an agronomic or horticultural perspective. More elaborated classifications are useful for special investigations into the diversity of a crop.