Visualization of A- and B-genome chromosomes in wheat (Triticum aestivum L.) x jointed goatgrass (Aegilops cylindrica Host) backcross progenies

Wheat (Triticum aestivum) and jointed goatgrass (Aegilops cylindrica) can c ross with each other, and their self-fertile backcross progenies frequently have extra chromosomes and chromosome segments, presumably retained from w heat, raising the possibility that a herbicide resistance gene might transf er from wheat to jointed goatgrass. Genomic in situ hybridization (GISH) wa s used to clarify the origin of these extra chromosomes. By using T. durum DNA (AABB genome) as a probe and jointed goatgrass DNA (CCDD genome) as blo cking DNA, one, two, and three A- or B-genome chromosomes were identified i n three BC2S2 individuals where 2n = 29, 30, and 31 chromosomes, respective ly. A translocation between wheat and jointed goatgrass chromosomes was als o detected in an individual with 30 chromosomes. In pollen mother cells wit h meiotic configuration of 14 II + 2 I, the two univalents were identified as being retained from the A or B genome of wheat. By using Ae. markgrafii DNA (CC genome) as a probe and wheat DNA (AABBDD genome) as blocking DNA, 1 4 C-genome chromosomes were visualized in all BC2S2 individuals. The GISH p rocedure provides a powerful tool to detect the A or B-genome chromatin in a jointed goatgrass background, making it possible to assess the risk of tr ansfer of herbicide resistance genes located on the A or B genome of wheat to jointed goatgrass.