CHROMOSOME LOCATION OF TWO LEAF RUST RESISTANCE GENES TRANSFERRED FROM TRITICUM SPELTOIDES TO T. AESTIVUM

Two homoeologous-recombination-produced gene transfer lines in which leaf rust resistance genes from Triticum speltoides Tausch were incorporated into the chromosome complement of Triticum aestivum L. emend. Thell. were analyzed. One line, F-7-3, originated from the cross T. aestivum cv. Neepawa × T. speltoides accession F and the other line, E-11-14, originated from the cross T. aestivum cv. Manitou × T. speltoides accession E. The lines were crossed with Chinese Spring monosomics. Segregation of the F2 progenies from monosomic F1's indicated that both genes were on chromosome 1B. The lines were then crossed with Chinese Spring ditelosomics 1BS and 1BL and the F1, plants were testcrossed to Manitou. Meiotic chromosome pairing in the F1 plants and the segregation of the telosomes and resistance in the testcrosses provided evidence that both gene transfers involved chromosome arm 1BL. The exchange points showed 41% and 4% recombination with the centromere in F-7-3 and E-11-14, respectively. Recombination between the transferred alien chromatin and the chromatin of the recipient wheat chromosome is either severely reduced or entirely absent when the wheat diploidizing mechanism is active.