Herbicide response polymorphism in wild populations of emmer wheat

The responses of wild populations of emmer wheat (Triticum dicoccoides), from different eco-geographical areas of Israel, to three herbicides, difenzoquat, chlortoluron and metoxuron, commonly used on cultivated wheats, were studied. Although cultivated wheats are polymorphic for a response to difenzoquat, all families of all populations of the wild species were resistant. The species was, however, polymorphic for response to both chlortoluron and metoxuron. In addition, there appeared to be differentiation between populations in the frequencies of resistant and susceptible morphs for these herbicides. There was also a close correspondence between the responses of individual families to chlortoluron and metoxuron, which suggests a common genetic control. The implications of these findings for understanding the evolution of herbicide resistance, and for developing strategies for breeding for resistance in the cultivated species are discussed.