A nuclear compatibility gene, Ncc-tmp, of Triticum timopheevi for the cytoplasm of Aegilops squarrosa

A nuclear genome of timopheevi wheat is compatible with the cytoplasm of Aegilops squarrosa, while that of durum wheat is incompatible, thus no euploid hybrids with this cytoplasm could be obtained. A euploid nucleus-cytoplasm (NC) hybrid of Triticum durum cv. Langdon was produced by introgressing a NC compatibility gene (Ncc-tmp) of T. timopheevi. Southern blot analysis, using one RAPD marker (S13(830)) that is tightly linked to Ncc-tmp and DNAs from a series of D genome chromosome substitution lines of Langdon, demonstrated that Ncc-tmp locates on chromosome 1A. A similar function of Ncc-tmp and Ncc-sqr of Ae. squarrosa for its own cytoplasm suggested that they are homoeoallelic. Homologous sequences of two other linked RAPD markers (R03(820) and R19(600)) were detected in all accessions of T. urartu but not in T. boeoticum. The result showed the conservation of sequences adjacent to Ncc-tmp in T. urartu, an A genome donor for emmer and timopheevi wheat. An analysis of gamma-gliadin showed that the NC hybrid possesses one allele that might have been introgressed from chromosome 1G of T. timopheevi. Together with this result, 3:1 segregation of plump and shriveled seeds in BC1 of the cross between (sqr)-T. timopheevi and T. turgidum suggested the presence of an additional and functional homoeoallelic Ncc-tmp in T. timopheevi.