Discovery of QTL for stay-green and heat-stress in barley (Hordeum vulgare) grown under simulated abiotic stress conditions

This study maps genomic regions associated with terminal heat- and drought-stress tolerance in barley (Hordeum vulgare L.). One hundred lines were randomly sampled from a ND24260 × Flagship doubled haploid population and evaluated for stay-green (SG) expression. SG expression including that of parental controls and commercial check varieties was evaluated in two controlled environments; one simulating terminal heat-stress, the other terminal water-stress. During grain-fill the greenness of the spikes (S), flag leaf (FL) and the first leaf under the flag leaf (FL-1) were phenotyped; visually (using a 0–9 scale) and via single-photon avalanche diode measurements. From the visual assessments, the green leaf area of the plant was determined, by using the difference in green area of the S and FL. Composite interval mapping detected 10 quantitative trait loci (QTL) for SG, positioned on chromosomes 3H, 4H, 5H, 6H and 7H; six of which were associated with terminal heat-stress and four with terminal water-stress. None were co-located with previously reported barley stress-response QTL and thus represent novel barley QTL. Although novel, some SG QTL mapped near chromosomal regions previously reported; such as the two heat-stress QTL mapped to bPb-5529 on 5H, adjacent to QTL reported for root length and root-shoot ratio. Detection of SG QTL in barley grown under simulated heat- and water-stressed conditions offers the potential of high through put screening for these traits. If confirmed in field trials, these genomic regions will be candidates for barley breeding programs targeting improved abiotic stress tolerance via marker-assisted selection.