Morphology and AFLP markers suggest three Hordeum chilense ecotypes that differ in avoidance to rust fungi

In Hordeum chilense Roem. & Schult., a high variation in the level of avoid ance to infection of barley leaf rust (Puccinia hordei Otth) occurs. Probab ly resulting from the properties of the stomata, the rust germ tube overgro ws stomata, and the infection process fails in an early stage. In the prese nt study we tested the hypothesis that the avoidance character occurs in ce rtain morphologically and molecularly distinct ecotypes of H. chilense. Eig hty-eight H. chilense accessions were inoculated with P. hordei to assess t he level of avoidance. The accessions were described for 30 morphological c haracters and three AFLP primer combinations. Cluster analysis using both m orphological and AFLP fingerprint data suggested three distinct clusters of accessions. One of the clusters had a particularly high level of avoidance . This putative subspecific taxon was characterized by shorter and wider sp ikes, more erect culms, a greater number of stomata per square centimetre o n the abaxial leaf side, and a shorter uppermost internode until flag leaf. All accessions clustered in this subspecific taxon were collected from hum id habitats. We conclude that H. chilense consists of at least three rather well defined, morphologically and genetically distinct subspecific taxa, o ne of which has a very high level of avoidance to barley leaf rust.