IBPGR morphological descriptors - their relevance in determining patterns within a diverse spring barley germplasm collection.

The International Board for Plant Genetic Resources (IBPGR) promotes a minimum set of morphological characters thought satisfactory for the custodial management of crop germplasm collections. The purpose of such conserved germplasm is as a genetic resource for future plant breeding programmes. Because future plant breeding requirements are not always known, the curator's strategy in maintaining an adequate germplasm resource is to conserve as wide a range of genetic diversity as possible. How is diversity measured to ensure a wide range of conserved germplasm? The IBPGR minimum descriptors detail genetic diversity at particular points in a genome corresponding to the observed characters. The purpose of the present study was to investigate whether diversity as identified by the IBPGR minimum set of descriptors could yield satisfactory measures of diversity in a contrasting set of genomic markers. A diverse spring-sown barley collection of 1379 cultivars was evaluated for the 12 IBPGR minimum taxonomic characters. An additional nine phenotypic characters and six biochemical markers were evaluated to enable diversity comparisons. Cluster analysis of the various sets of data revealed groups of accessions for each of the three data sets. A poor level of agreement (congruence) between data sets was observed in all comparisons indicating that, for cultivated barley at least, diverse collections according to the IBPGR minimum descriptors is not necessarily related to equivalent levels of diversity in other genetic characters. Implications of the relevance of the IBPGR descriptor list and appropriate collection strategies are discussed.