D‐Genome Substitution‐Monosomics of Durum Wheat 1

Each of the D‐genome chromosomes was substituted for its homoeologous A‐ and B‐genome chromosomes in Triticum turgidum L. cv. durum ‘Langdon’. All 14 possible substitution‐monosomics were obtained by crossing the appropriate ‘Chinese Spring’ nullisomic‐tetrasomic ( Triticum aesthium L.) with Langdon. Selfing these F 1 's and selecting for 14 chromosome pairs in the F 2 and F 3 resulted in the disomic substitution of a D‐genome chromosome pair for a homoeologous A‐ or B‐geuome chromosome pair. When these disomic substitutions were backcrossed to Langdon, the BC 1 progenies were substitution‐monosomics with 13 pairs plus two univalents (13″ + 2′). One of the univalents was an A‐ or B‐genome chromosome and the other univalent, the homoeologous D‐genome chromosome. In repeated backcrosses to Langdon durum, the D‐genome chromosomes were transmitted through the female gametes 33% of the time on the average. The substitution‐monosomics were more fertile, more vigorous, and the D‐genome chromosomes were transmitted through the female gamete at a higher rate than the durum monosomics. They can be used for many of the same genetic studies as the monosomics in hexaploid wheat.