Breeding Behavior of the Cytogenetically Engineered Wheat-Rye Translocation Chromosomes 1RS.1BL
The rye (Secale cereale L.) chromosome arm in the wheat-rye centric translocation 1RS.1BL in wheat (Triticum aestivum L.) had been engineered by induced homoeologous recombination to remove the associated breadmaking quality defect. From a range of primary wheat-rye recombinant chromosomes, two classes of multipoint translocated chromosomes were assembled, MA and Te, that contain Gli-B1 and Glu-B3 loci of wheat and are missing the Sec-1 locus of rye. Their disassembly rates by recombination with normal 1BS and 1RS and the segregation ratios from heterozygotes were studied in populations involving the original, unmodified translocation 1RS.1BL and chromosomes 1B from several wheat cultivars. Overall, the four-point translocation chromosomes MA recombined with 1BS with 4.4% frequency; their intercalary rye segment recombined with 1RS with 3.2% frequency. The overall recombination frequency of the three-point translocation chromosome Te1 with 1BS was 18.1% but only 5.4% resulted in the disassembly of the chromosome. The remaining 12.7% recombination was in the terminal wheat segment and in most cases it introduced new alleles at the wheat storage protein loci. The male transmission rate of all engineered chromosomes was similar to that of the original 1RS.1BL translocation. In competition with 1B, it was reduced to about 22 to 37%. As a result of the disassembly and reduced transmission, the probability of selection of homozygotes for unaltered engineered chromosomes among the progenies of heterozygotes with 1B was about 15 to 16%.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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