Hybridisation between wheat and Aegilops geniculata and hybrid fertility for potential herbicide resistance transfer

Hybridisation between wheat and Aegilops geniculata was quantified in a 4-year crossing experiment in the glasshouse, using three wheat cultivars as pollen donors and herbicide resistance as a phenotypic marker. Hybridisation rates ranged from 5% to 74%. Most of the hybrids were self-sterile. However, seven F 2 seeds were obtained from 165 A. geniculata-wheat hybrids. Hybrid seeds were found in all backcross (BC 1 ) combinations at average rates of 4.2% (0-26.3%) and 5.88% (0-34%) under glasshouse and field experiments, respectively, with significant differences among years and cultivars. Wheat cultivars, F 1 and BC 1 plants, were resistant to herbicides while A. geniculata plants were susceptible. In the subsequent generations, although few plants were available, the BC 1 F 1 had a certain degree of fertility and the fertility increased in the F 2 plants, with one plant that reached 66.7%. The commercial growing of genetically modified herbicide-tolerant wheat is expected to have the potential for the inserted gene to escape from the crop and become incorporated in a closely related wild species, conferring a competitive advantage to these conferring weeds. Determining the frequency of crop-wild transgene flow and the fertility of the formed hybrids is a necessity for risk assessment. Data presented here provide new knowledge on the potential A. geniculata-wheat herbicide resistance transfer.