Towards Molecular Tagging of Karnal Bunt Resistance Gene(s) in Wheat

We describe preliminary results of cosegregation of a DMA probe with Karnal bunt resistance gene(s) in wheat. The tagging strategy utilized 4 uniformly resistant and 13 uniformly susceptible F₃ families from a cross of Karnal bunt resistant (HD29) and susceptible (WL711) lines of Triticum aestivum. Bulked DNA of 8–10 plants in each family were tested by gel blot DNA hybridization. Thirty three per cent of the probes (11/33) detected restriction fragment length polymorphism (RFLP) between Karnal bunt resistant and susceptible lines. Probe Cxp1 from chromosome group 6 detected the resistant parent (HD29) polymorphic band in all the resistant family bulks but was missing in 6 uniformly susceptible family bulks. A similar pattern was observed with probe XKsu G34 from 1DL. The intensity of the resistant parent band in the susceptible family bulks was less as compared to the resistant family bulks. Probe Xksu H8 which mapped on chromosomes 2, 3, 5 and 7D on the T. tauschii map did not differentiate resistant family bulks from susceptible family bulks. Our results indicated that one or more resistance gene(s) are located on chromosome groups 1 and 6 of wheat.