USE OF LOCUS-SPECIFIC AFLP MARKERS TO CONSTRUCT A HIGH-DENSITY MOLECULAR MAP IN BARLEY

By using 25 printer combinations, 563 AFLP markers segregating in a re combinant inbred population (103 lines, F-9) derived from L94/Vada wer e generated. The 38 AFLP markers in common to the existing AFLP/RFLP c ombined Proctor/Nudinka map, one STS marker, and four phenotypic marke rs with known map positions, were used to assign present AFLP linkage groups to barley chromosomes. The constructed high-density molecular m ap contains 561 AFLP markers, three morphological markers, one disease resistance gene and one STS marker, and covers a 1062-cM genetic dist ance, corresponding to an average of one marker per 1.9 cM. However, e xtremely uneven distributions of AFLP markers and strong clustering of markers around the centromere were identified in the present AFLP map . Around the centromeric region, 289 markers cover a genetic distance of 155 cM, corresponding to one marker per 0.5 cM: on the distal parts , 906 cM were covered by 277 markers, corresponding to one marker per 3.3 cM, Three gaps larger than 20 cM still exist on chromosomes 1, 3 a nd 5. A skeletal map with a uniform distribution of markers call be ex tracted from the high-density map, and can be applied to detect and ma p loci underlying quantitative traits. However, the application of thi s map is restricted to barley species since hardly any marker in commo n to a closely related Triticum species could be identified.