Thinopyrum ponticum Chromatin-Integrated Wheat Genome Shows Salt-Tolerance at Germination Stage

A wild wheatgrass, Thinopyrum ponticum (2n = 10x = 70), which exhibits substantially higher levels of salt tolerance than cultivated wheat, was employed to transfer its salt tolerance to common wheat by means of wide hybridization. A highly salt-tolerant wheat line S148 (2n = 42) was obtained from the BC(3)F(2) progenies between Triticum aestivum (2n = 42) and Th. ponticum. In the cross of S148 × salt-sensitive wheat variety Chinese Spring, the BC(4)F(2) seeds at germination stage segregated into a ratio of 3 salt tolerant to 1 salt sensitive, indicating that the salt tolerance was conferred by a dominant gene block. Genomic in situ hybridization analysis revealed that S148 had a single pair of Th. ponticum–T. aestivum translocated chromosomes bearing the salt-tolerance. This is an initial step of molecular breeding for salt-tolerant wheat.