Understanding Root Responses to Drought in PeanutWater-deficit and associated abiotic stresses like thermal stress significantly impact root and shoot development, reproduction, resource partitioning, and yield quality and quantity. The long-term goals of our research group are to achieve a basic understanding of mechanisms of abiotic stress responses in crop plants and the impact of stress on key developmental processes. Research in model systems has shown that creative, field-based approaches in combination with controlled chamber experiments are needed to study abiotic stress tolerance in crop plants. In our current research, we have identified peanut genotypes with contrasting responses to both heat and water-deficit stress under both field and controlled chamber conditions. Preliminary data suggests that the diversity for abiotic stress tolerance we have identified is, in part, due to morphological differences in root morphology and plasticity. Here, we propose to employ an integrated approach utilizing root morphology (in the field and controlled enviroments) screening, whole-plant physiology and agronomy, transcriptomics, and tissue/stage specific quantitative proteome profiling to elucidate the mechanisms of water-deficit stress tolerance in peanut roots. We will test our hypothesis on root morphology and physiological adaptations to stress tolerance in both production field settings, using relevant irrigation levels, and controlled environment/glasshouse studies. Successful completion of this work will provide, a) insight into the underlying physiological and molecular mechanisms controlling peanut abiotic stress responses and the impact of those responses on whole-plant physiology and yield; b) identification of novel sources of genetic material for breeding stress tolerance in peanut; c) new transcriptome and proteome data to the peanut and legume community; d) gene networks in water-deficit stress signaling; and e) functional markers and potential root phenotype traits for breeding abiotic stress tolerance in peanut.