Comparative genetic mapping of homoeologous genes for the chlorina phenotype in the genus Triticum

Triticum monococcum L. (2n = 2x = 14, A(m)A(m) genome) is one of the most ancient of the domesticated crops in the Middle East, but it is not the ancestor of the A genome of durum wheat (T. durum Desf. 2n = 4x = 28, genomes BBAA) and bread wheat (T. aestivum L., 2n = 6x = 42, genomes BBAADD). It has been suggested that some differentiation has occurred between the A(m) and A genomes. The chlorina mutants at the cn-A1 locus located on chromosome 7AL have been described in T. aestivum L. and T. durum, and a chlorina mutant has been found in T. monococcum. The aims of our study were to establish linkage maps for chlorina mutant genes on chromosome 7A of T. aestivum and T. durum and chromosome 7A(m) of T. monococcum and to discuss the differentiation that has occurred between the A and A(m) genomes. The chlorina mutant gene was found to be linked with Xhbg234 (8.0 cM) and Xgwm282 (4.3 cM) in F-2 plants of T. aestivum ANK-32A/T. petropavlovskyi k54716, and with Xbarc192 (19.5 cM) and Xgwm282 (12.0 cM) in F-2 plants of T. durum ANW5A-7A/T. carthlicum #521. Both the hexaploid and tetraploid wheats contained a common marker, Xgwm282. In F-2 lines of T. monococcum KT 3-21/T. sinskajae, the cn-A1 locus was bracketed by Xgwm748 (25.7 cM) and Xhbg412 (30.8 cM) on chromosome 7A(m)L. The distal markers, Xhbg412, Xgwm282, and Xgwm332, were tightly linked in T. aestivum and T. durum. The common marker Xhbg412 indicated that the chlorina mutant genes are located on chromosome 7AL and that they are homoeologous mutations.