Identification of Early Vigor QTLs and QTL by Environment Interactions in Wheat (Triticum eastivum L.)

Crop productivity is highly dependent on successful seed germination and seedling establishment. This study evaluated two mapping populations, Batavia/Ernie (double haploid) and Synthetic/Opata (recombinant inbred lines), for early vigor under water stress and normal growing conditions. Significant gene, environment (water), and gene by environment interaction effects were observed. Broad sense heritability was 29 and 40% for the Batavia/Ernie and Synthetic/Opata populations, respectively. Quantitative trait loci (QTL) were analyzed based on single and multienvironment models. The two mapping populations differed in the number and locations of QTLs except qNev.uwa.4AL was identified in both populations under the non-stress condition, while qSev.uwa.3BL was specifically expressed under the stress condition in the Synthetic/Opata population. QTL by environment interaction (QEI) enabled identification of nine QTLs, including those identified by the single environment approach. Phenotypic variation expression (PVE) of QEIs ranged from 4.8 to 14.9% across the populations. Larger proportion of PVE of QEIs was explained by the additive components. Favorable alleles for three of the QTLs identified in the Synthetic/Opata population were derived from Synthetic, while Batavia contributed favorable alleles to a QTL on the long arm of chromosome 1D in the Batavia/Ernie population. QTL detected under water stress (qSev.uwa.3BL) co-located with the DREB 1 gene, which was mapped between markers Xmwg818 and Xfbb117 (58.1-77.6 cM). QTLs with high proportion of additive components can be validated for marker assisted gene pyramiding and selection.