This Is AuburnElectronic Theses and Dissertations

Integration of physiological and molecular approaches for selecting peanut genotypes with superior drought tolerant and nitrogen fixation traits




Wang, Xu

Type of Degree

Master's Thesis


Crop Soils and Environmental Sciences


The vulnerability of peanut to drought varies depending on physiological characteristics, crop growth stages, and environmental conditions. This study examined the effects of drought stress on symbiotic nitrogen fixation (SNF), carbon isotope discrimination and transcriptional profiles of various peanut genotypes. Two parental lines (Tifrunner and C76-16) and 14 recombinant inbred lines were evaluated under three irrigation regimes (irrigated control, middle-season drought and late-season drought) in rainout shelters. A greater reduction of the percentages of shoot N derived from the atmosphere (%Ndfa) and carbon isotope discrimination (Δ) occurred under middle-season drought than late-season drought. Under middle-season drought, both %Ndfa and Δ were higher in drought tolerant lines than drought susceptible lines, and a positive correlation between %Ndfa and Δ was observed under both drought treatments. Genes responding to drought stress were examined in four genotypes (drought tolerant: C76-16 and AU-587; drought susceptible: Tifrunner and AU-506) under irrigated control and middle-season drought. Whole-transcriptome sequencing analysis identified 7,780 differentially expressed genes (DEGs) in Tifrunner, 9,767 in AU-506, 12,348 in AU-587 and 13,005 in C76-16. Of the identified DEGs, 2,457 DEGs were shared by all four genotypes. Functional analysis of the shared DEGs identified a total of 139 enriched gene ontology (GO) terms and 43 enriched Kyoto encyclopedia of genes and genomes (KEGG) pathways. This research expands our current understanding of the mechanisms that facilitate peanut drought tolerance and shed light on breeding advanced peanut lines to combat drought stress.