Breeding Behavior of Chromosomes 1R Cytogenetically Engineered for Breadmaking Quality in Hexaploid Triticale

摘要

To create genetic potential for breadmaking quality improvement in triticale (X Triticosecale Wittmack), chromosome 1R was cytogenetically engineered to introduce wheat (here, Triticum turgidum var. durum L.) gluten loci while removing secalin loci. Each engineered chromosome is a wheat-rye (Secale cereale L.) translocation with up to six translocation breakpoints. Consequently, these chromosomes may disassemble by crossing over with normal chromosomes. To determine their transmission rates through gametes and their recombination rates with normal 1R, they were tested in a wide range of genetic backgrounds over several years, both in standard sexual reproduction and in androgenic doubled haploids. Male transmission rates of all chromosomes were significantly lower than female and than random, which suggests reduced genetic compensation of translocations. Recombination frequencies in individual segments were similar to those observed during chromosome development. Reduced male transmission combined with recombination of the engineered chromosomes resulted in relatively low recovery rates of homozygotes on self-pollination. The recovery rate of the chromosomes via androgenesis was no different than transmission via pollen in sexual reproduction, implying that normal chromosome 1R may be involved in the process of androgenesis. Overall, chromosome FC2 appeared to be the most suitable for breeding, as it most completely resolves the gluten issue while offering a reasonably high transmission rate and good stability over generations.