QTL for chlorophyll fluorescence of barley plants grown at low oxygen concentration in hydroponics to simulate waterlogging

Waterlogging is a major factor limiting barley grain yield worldwide. Climate change will likely increase this water stress in Northern Europe. Breeding for waterlogging tolerance (WLT), as for other abiotic stresses, is difficult, but identification of genetic markers linked to genes affecting WLT could facilitate the breeding process. To identify a suitable marker population, parents of 14 double-haploid (DH) barley populations were tested for segregation of biomass growth reduction in waterlogged soil. The most interesting was found in the offspring from crossing cv. Psaknon and breeding line (SLUdt1398 x Mona(4)). Hence, 120 DH-lines derived from this cross were phenotyped for the chlorophyll fluorescence parameter quantum yield (QY) of electron transport of PSII from leaves of hypoxia-stressed plants and further genotyped with 384-SNP Illumina GoldenGate Bead Array. Five quantitative trait loci (QTL) for QY, with a narrow sense heritability of 0.87, were identified on chromosomes 4, 6 and 7H. They had additive effects ranging from 0.74 to 1.35 % with LOD scores from 3 to 12 and explained variance from 6 to 29 %. The major alleles for high QY were from cv. Psaknon; i.e., QY was low if the alleles from cv. Psaknon were not present. Based on leaf necrosis and residual biomass data, the four most interesting QTL may be also in two other populations with completely different progeny, which shows a certain stability of these QTL. The possibility of using marker assistant selection for WLT is discussed, as is possible concurrent improvement of drought tolerance and grain yield.