Drought Tolerance Compared Between Two Eutrema salsugineum Ecotypes and Their Recombinant Inbred Lines

Abstract

Despite drought accounting for over 80% of agricultural losses, little progress has been made towards improving drought tolerance in crops. My approach to identifying traits underlying drought tolerance involved a comparison between two accessions of the crucifer, Eutrema salsugineum, that display differential tolerance to water deficits. The accessions, originating from the semi-arid Yukon, Canada, and a monsoonal region of Shandong, China, were subjected to a two-step, water deficit and recovery protocol to identify physiological characteristics that discern their drought-responsive behaviour. Traits that discriminate between the ecotypes were used to screen recombinant inbred lines (RILs) that were generated by crossing Yukon and Shandong parent plants. Selected physiological measurements were: anthocyanin accumulation, cut rosette water loss (CRWL), solute potential, relative water content (RWC), static leaf water content (SLWC), specific leaf area (SLA), and OJIP fluorescence emission. Of the measurements taken, CRWL measurements and anthocyanin content distinguished the Yukon ecotype from the Shandong ecotype during the first drought exposure whereas SLA and fluorescence responses differentiated these accessions better after plants that experienced the first drought were rewatered and recovering or undergoing a second drought treatment. Sixty-eight RILs were screened using SLA and OJIP fluorescence emission. SLA and OJIP measurements varied among the recombinant inbred lines (RILs) with many lines showing responses to water deficit intermediate to those of the parental lines. Evidence of heritability in SLA and/or OJIP responses to water deficits would make them useful phenotypic markers for identifying quantitative trait loci (QTLs) associated with drought tolerance in future work.