Genetic variation in barley landraces from Bhutan

Summary In Bhutan, barley is usually grown in mountainous regions over 2,000 m elevation. The barleys investigated were six-rowed naked, and classified into three groups by spike and awn characters; lax spike and long awn, dense spike and long awn, and dense spike and elevated hood. They also varied in spike color; yellow, purple and black. For isozymes, there was no variation at Aat2 and Aat3 loci for aspartate aminotransferase in the Bhutanese barley.However, allelic variations at Est1, Est2 and Est4 loci for esterase were detected, and three genotypes consisting of their allelic combinations were found. Most of the collections were heterogeneous for these features. Combinations between spike-awn types and esterase genotypes were not at random, indicating that genetic diversities resulted from mechanical mixtures of different types. These types were distributed with geographical regularity in Bhutan. In comparing the spike-awn type and esterase genotype in barley collections from other regions of the Himalayas, the Bhutanese barleys were s-imilar to the Tibetan ones, but were much different from the Nepalese barleys. This suggests that the Bhutanese barleys had been introduced from Tibet.