An understanding of the way in which plants respond and adapt to stress conditions is of fundamental importance for the generation of new varieties of staple crop species to allow agricultural yield to be maintained in the face changing land use and impending global climate changes. A central consequence of a variety of stress conditions is oxidative damage due to increased production of reactive oxygen species and other free radicals.Much progress has been made in understanding the response of plants to oxidative stress and particular attention has focused on identifying and characterizing the antioxidant machinery and specific protective proteins and metabolites. What is often overlooked, is that cellular metabolism must also be reconfigured to support increased demands for reductant, for metabolites with antioxidant activity and to provide precursors for the synthesis of protective metabolites. This metabolic change can be profound and is a central element of the array of molecular events that lead to stress tolerance. However, the exact nature of the metabolic change has not been quantified and a precise understanding of how the competing demands on central and secondary metabolism are met is not known. Metabolic regulation is a multi-faceted process being mediated at transcriptional, post transcriptional, post translational, structural (protein- protein) and allosteric levels. Therefore understanding metabolic regulation requires analysis of the hierarchical importance of each of these levels under each given biological condition. For this reason in the project proposed here particular attention will be paid to dissecting the level at which metabolic change is effected in different parts of the network(change in enzyme abundance versus regulation of enzyme activation state / efficiency) and the reconfiguration of metabolism in response to oxidative stress.