Isozymic estimation of the biodiversity of Spanish Avena sativa L. landraces stored in a germplasm bank

Twenty-six accessions from the Spanish national germplasm bank of oats at the Plant Genetic Resources Centre (CRF-INIA) collection of Avena sativa L. were analyzed by isozyme. These accessions were a subset of the core collection and were selected on the basis of their positive agricultural characteristics. The sites where the 26 accessions to the collection were gathered were representative of the relative weightings, both in the core and in the entire collection, of the various agroclimatic regions of Spain. The objectives of the study were (i) to ascertain the degree of isozymic variability between and within accessions; (ii) to compare the results with the variability recorded in a prior isozyme study with a larger, random, sample of the entire collection in order to validate the criteria used for the selection of the 26 accessions; and (iii) to define groupings of accessions on the basis of their genetic distances, this being a piece of information of value for the utilization of germplasm. Each of the accessions had its own distinctive array of isozyme phenotypes. High overall diversity was detected (phenotypic variability index Pj = 0.576). Almost one-third (29%) of the overall variability was intra-accession variability. There were large differences in intra-accession variability, and accessions were divided into 3 groups on the basis of their internal diversity, estimated from Pj, and the Shannon index, Hj. The isozymic variation in the 26 accessions was similar to that of the entire collection, which indicates that the method used to select the subset did not cause any loss of genetic diversity. The PCA defined 3 clusters of accessions with a few outliers. The grouping showed only a limited link to the geographical origin of the accessions, but had a noteworthy relationship with the agroclimatic conditions at the collection sites. © 2005 Science From Israel / LPPLtd.