Marker-assessed retention of wheat chromatin in wheat (Triticum aestivum) by jointed goatgrass (Aegilops cylindrica) backcross derivatives

With the advent of herbicide-resistant wheat (Triticum aestivum L.), there is a concern with the potential for gene migration between wheat and jointed goatgrass (Aegilops cylindrica Host.). This is especially true for genes on the D genome, since this genome is shared by wheat and jointed goatgrass. To study the potential for gene migration, BC1 and BC2 plants were produced with jointed goatgrass as the male recurrent parent. To determine if wheat chromatin was retained at expected Mendelian frequencies in these backcrosses, 14 simple sequence repeats (SSR) markers associated with the long and short arms of the D genome chromosomes were used. Chi-square analysis showed that 12 of the 14 markers fit the expected ratio for retention of wheat alleles in the BC1 generation. In the BC2 generation, 11 of the 14 markers fit the expected frequencies for the retention of wheat alleles. The markers not fitting the expected frequencies in both generations deviated in the direction of more heterozygotes than expected, indicating a higher than expected retention of wheat alleles. Furthermore, recombination between the D genome chromosomes of the two species was observed. On the basis of these results, it appears that it is possible for a gene on the D genome of wheat to move into jointed goatgrass if the BC1 and BC2 generations were produced in the field.