Natural hybridization between wheat (Triticum aestivum L.) and its wild relatives Aegilops geniculata Roth and Aegilops triuncialis L.

Abstract

BACKGROUND: Cultivated bread wheat (Triticum aestivum L.) spontaneously hybridizes with wild/weedy related Aegilops populations, but little is known about the actual rates at which this hybridization occurs under field conditions. It is very important to provide reliable empirical data on this phenomenon in order to assess the potential crop-wild introgression, especially in the context of conducting risk assessments for the commercialization of genetically modified (GM) wheat, as gene flow from wheat to Aegilops species could transfer into the wild species genes coding for traits such as resistance to herbicides, insects, diseases or environmental stresses.RESULTS: The spontaneous hybridization rates between wheat and A. geniculata and A. triuncialis, which are very abundant in the Mediterranean area, have been estimated for the first time in the northern part of the Meseta Central, the great central plateau which includes the largest area of wheat cultivation in Spain. Hybridization rates averaged 0.12% and 0.008% for A. geniculata and A. triuncialis, respectively. Hybrids were found in 26% of A. geniculata and 5% of A. triuncialis populations, at rates that can be ≤3.6% for A. geniculata and 0.24% for A. triuncialis. CONCLUSION:The detection of Aegilops spp.-wheat hybrids in Aegilops populations indicates that gene flow can occur, although wheat is considered a crop with a low-to-medium risk for transgene escape. These data on field hybridization rates are essential for GM wheat risk assessment purposes.

Hybridization in agricultural weeds: A review from ecological, evolutionary, and management perspectives

“…Aegilops species are related to wheat and at least one species, jointed goatgrass ( Aegilops cylindrica Host), hybridizes with wheat and reduces wheat yield in North America (Mallory‐Smith et al, 2018). Ovate goatgrass ( A. geniculata Roth) and barbed goatgrass ( A. triuncialis L.) have been reported to hybridize with wheat in Europe; hybridization rates depend on factors including proximity of Aegilops plants to the wheat field, population genetics of both species, and climatic conditions (Loureiro et al, 2023). Thus, it is plausible that increased sympatry between wheat and Aegilops species in Europe will promote crop‐to‐weed introgression and weediness (Ostrowski et al, 2016).…”