Fine mapping of short rachilla hair gene (srh) in Barley and an association study using flanking molecular markers and world germplasms

Short rachilla hair in barley is controlled by a recessive gene srh that is located on the long arm of barley chromosome 5H. It shows a skewed geographical distribution toward the Occidental regions of barley cultivation. This morphological character is an attractive trait to study the phylogeny of barley. In a previous study, srh was mapped between two markers at a distance of 1.6 and 0.5 cm in the proximal and distal side, respectively. An integrated map was constructed during this experiment using the data from two F₂ populations and 320 homozygous recessive short rachilla hair plants from another population. The CAPS marker k06288KU and SSR marker Bmag0223 are found to be flanking short rachilla hair locus srh at a genetic distance of 1.6 and 4.0 cm, respectively. World barley germplasm collections of 192 accessions differing in rachilla type were surveyed using k06288KU and Bmag0223. SSR marker Bmag0223 showed a better association with srh. In Europe, North Africa and Ethiopia, the frequency of Bmag0223 allele A was high regardless of rachilla type, but in East Asia allele A was closely associated with short rachilla. On the basis of marker association and genetic diversity, the origin of short rachilla hair character in barley is discussed.