Abstract
Barley mild,mosaic virus (BaMMV) and Barley yellow mosaic virus (BaMMV) are responsible for one of the most important disease of winter barley in Europe. The aim of this work was to characterize the reaction of 26 old French barley cultivars to mosaic viruses. They were tested by mechanical inoculation with BaMMV. Some resistant ones were crossed with susceptible and resistant genotypes to study the genetic determinism of their resistance. The diversity of all old cultivars was then assessed with morphological, isozyme and molecular markers. Seven cultivars out of 26 were fully resistant to BaMMV. Crosses with a susceptible cultivar showed that three of them carried two recessive resistant genes. One of these genes was allelic to ym4 No segregation in F2 was found for a cross with the ni. 'Russia 57' indicating char the second gene may be allelic to ym11. The factorial correspondence analysis with all markers resulted in three main groups. One of these included the seven resistant old cultivars suggesting that they are related and thar their resistance genes derived from the same origin.