Genetic diversity in landrace populations of Hordeum vulgare L. from Sardinia, Italy, as revealed by RAPDs, isozymes and morphophenological traits

Barley is the second most widely cultivated cereal on the island of Sardinia. It is grown for green fodder, grain and straw, all of which are used for animal feed. The cultivation of modern varieties is limited and many farmers grow local populations of the six-row landrace 'S'orgiu sardu'. Twelve local populations (20 strains per population) were evaluated for 13 random amplified polymorphic DNA (RAPD) markers, six isozyme loci and five morphophenological traits. Results showed that Sardinian barley is characterized by a lax six-row spike and is, in general, a spring type. Isozyme polymorphism was detected for only two esterase loci (Est1 and Est4). The genetic variation for all types of markers was found located mostly within population (about 84% for isozymes and morphophenological traits and 89% for RAPDs). This finding appears to confirm the hypothesis that the populations studied belong to the same landrace called 'S'orgiu sardu' by farmers. A geographical differentiation between southern and northern populations was found in relation to distinct environmental characteristics. Taking into account all types of marker 209 (90.5%) different genotypes were identified out of 231 individuals. The overall results confirm the high variability that can be found within landrace populations, underlining the value of landraces as a source of genetic variation.