Telosomic mapping of four genetic markers in durum wheat

Few morphological or physiological genes that are useful as genetic markers have been mapped in durum wheat (Triticum turgidum L.). Our objective was to use aneuploid stocks to map four recessive genes in durum wheat. The genes included cn-A1d in the chlorina mutant CDd6, cn-B1a in the chlorina mutant CDd1, cc in a chocolate-brown chaff (CBC) stock, and bh in a supernumerary spikelet stock. Previous studies had located cn-A1d to 7AL, cn- B1a to 7BL, bh to 2AS, and cc to an unknown arm of chromosome 7B. We observed independent segregation of cc and cn-B1a in the F2 and F3 of CBC/CDd1. Segregation for chaff color among disomic F2 plants of Langdon dimonotelosomic 7BS/CBC-CDd1 indicated that cc was in 7BS. Parental marker lines were crossed to appropriate Langdon dimonotelosomic or double ditelosomic plants. We crossed double-telotrisomic (13' + tlt'') F1 plants to the parental marker line and classified the testcross plants for chromosome number and marker phenotypes. The map distance of each gene from the centromere was 46.6 ± 38 cM for cn-A1d in 7AL, 42.6 ± 4.3 cM for cn- B1a in 7BL, 33.5 ± 41 cM for cc in 7BS, and 8.5 ± 2.1 cM for bh in 2AS.