Microgeographic edaphic differentiation in hordein polymorphisms of wild barley.

Genetic diversity in the storage protein hordein encoded by two loci, Hor1 and Hor2, was analyzed electrophoretically in seeds from 123 individual plants of wild barley, Hordeum spontaneum, the progenitor of cultivated barley. The test was conducted in two topographically different 100 meter transects in Israel, each equally divided into basalt and terra rossa soil types. Altogether 15 Hor1 and 16 Hor2 phenotypes were detected; 7 phenotypes in Hor1 and 5 in Hor2 were common. Significant differentiation of both Hor1 and Hor2 phenotypes and their associations was found with soil type and topography. Likewise, significant correlations were found between hordein phenotypes and allozyme types detected in a previous study. Our results suggest that at least part of the hordein polymorphisms in wild barley is adaptive and selected by soil and topographic differences over very short distances.