Plants' responses to changes in their environments may be crucial for survival and reproduction, particularly under stressful conditions. The term 'reaction norm' refers to the responses of an organism (actual and potential) to environmental variation. The nature of these responses to the environment is under genetic control, and there are several ways that control can be manifested. The form of the genetic control is important because it will determine whether selection, either in the wild or in agriculture, can alter the ways that plants respond to changes in environmental factors such as light, water, nutrients or herbivores. The experiments being undertaken will reveal the genetic components of response to a gradient in soil nutrients, using a model plant system, Arabidopsis thaliana. In addition, we will impose a regime of artificial selection on Arabidopsis populations to determine the ability of these plants to alter their reaction norms, that is, to change their abilities to respond to changes in the level of nutrients. The results of these two sets of experiments will provide a better understanding of the genetic determination of reaction norms, and of how selection may operate to change reaction norms. Such an understanding may become increasingly important as we try to evaluate the impact of global environmental change on both wild and agricultural plant species.
