The occurrence of seed-producing wheat x jointed goatgrass hybrids in infested wheat fields suggests the possibility of gene flow between the two species. This study investigates 'Madsen' wheat x jointed goatgrass F��� and reciprocal backcross derivatives produced in experimental field plantings. Electrophoresis of the high molecular weight (HMW) glutenin seed proteins, chromosome counts, and morphological studies were used to better understand the genetics of these hybrids, and to provide a baseline for evaluating hybrids collected in natural populations. The HMW glutenin profiles are a useful diagnostic tool because the banding patterns, in the 68-120 kDa molecular weight range, are species-unique (three bands for goatgrass, four bands for wheat) and can be used to trace parentage in the hybrid seed on the basis of band contribution. Experimental hybrids show considerable diversity in banding profiles (9 patterns of three to six bands). Diversity in number of different glutenin profiles and number of subunits per seed decreases in more advanced generations (BC��� and BC���S���). Chromosome counts confirm the direction of the crosses and vary as follows: 35 chromosomes for F���; 36 to 57 for BC���; 28 to 49 for BC���; and 33 to 52 for BC���S���. A chromosome number of 28 suggests that jointed goatgrass (2n=4x=28) was the recurrent backcross pollen donor, while numbers closer to 42 and above point to wheat (2n=6x=42) as the pollen donor. Partial female fertility was found in all generations, as well as full self-fertility in BC��� and BC���S��� plants. Analysis of the HMW glutenin profiles of the progeny seeds verifies that hybridization can go in either direction, with most banding patterns similar to either jointed goatgrass or wheat. The resulting potential for gene flow from wheat to jointed goatgrass calls for continued study of these hybrid derivatives. / Graduation date: 2001

Graduation date: 2002