DISSECTION AND EXPLOITATION OF GENE NETWORKS TO IMPROVE PEANUT YIELD UNDER DROUGHT

OBJECTIVE 1: Document the DNA variants that distinguish the most drought-tolerant and susceptible peanut cultivars. An initial step towards understanding the genetic basis of quantitative trait variation involves documenting all potential causal DNA sequence variants. To this end, we will build a new reference genome for the highest yielding cultivar under drought and document all sequence variants between Line-7 and the recently published "Tifrunner " peanut genome. We will then re-sequence six other lines that span a gradient from very drought-susceptible to tolerant and build a database of all putatively functional variants across all genotypes.OBJECTIVE 2: Dissect the molecular basis of gene expression and physiological responses to drought. Here, we will take an integrative approach to understand peanut drought responses by simultaneously assaying gene expression, leaf-level physiology, and yield in a replicated soil moisture manipulation experiment. By testing the relative expression of alleles from drought-tolerant and susceptible parents in F1 hybrids, we will be able to define the potential causal variants that regulate gene expression and affect downstream physiology and whole-plant phenotypes.OBJECTIVE 3: Develop molecular markers for alleles that improve yield under drought conditions. The role of genetic diversity observed under Objectives 1-2 will be tested here through the development and analysis of an F2 mapping population. Beneficial alleles will be modeled from the allele-specific expression results (Objective 2) and markers will be developed from known variants (Objective 1). These alleles will be leveraged in marker-assisted selection among crosses between the most drought tolerant Line-7 genotype and other elite cultivars to improve drought tolerance in the peanut breeding program.