Quantitative trait locus mapping for carbon isotope ratio and root pulling force in canola

Abstract

Abstract Carbon isotope ratio (δ13C) and root pulling force (RPF) are associated with dehydration avoidance in plants. The δ13C measures the efficiency of C gain relative to water loss, whereas RPF, the vertical force required to pull plants from the ground, indirectly estimates root‐related dehydration avoidance capacity. To determine quantitative trait loci (QTL) controlling these traits in canola (Brassica napus L.), a mapping population was evaluated in 2011 and 2012 in Fort Collins, CO. The split‐plot experiment had two moisture regimes (main plot) and 148 doubled haploid lines (subplot), replicated three times. Analysis of variance indicated highly significant (P < .01) variation among genotypes for δ13C, RPF, days to flowering, and several other agronomic traits. In 2011, δ13C was correlated (P < .01) with days to flowering in both moisture treatments (r = .41 dry, 0.31 wet) and with fresh biomass in the dry treatment (r = .64). The RPF was consistently correlated with plant height (r = .32–.54, P < .01) and fresh biomass (r = .17–.58, P < .05) in all environments. In 2011, QTL were detected on chromosomes A09 and C08 for δ13C and on chromosomes A05, C01, C04, and C08 for RPF. The QTL for δ13C, RPF, and plant height co‐localized on C08. In 2012, QTL were detected on A02 for δ13C and on C01 and C08 for RPF. Moderate heritability and low QTL × environment interaction for δ13C and RPF suggest that if validated, markers for these traits could be used in marker‐assisted selection.