QTL mapping of dormancy in Barley using the Harrington/Morex and Chevron/Stander mapping populations

Grain dormancy in barley (Hordeum vulgare L.) is quantitatively inherited. Low levels of dormancy before harvest can lead to pre-harvest sprouting (PHS) in the field, which affects grain and malt quality. The objective of the present study was to determine the locations and effects of quantitative trait loci (QTLs) controlling dormancy in two F1–derived doubled-haploid (DH) populations from the crosses ‘Harrington’/‘Morex’ and ‘Chevron’/‘Stander’. The progenies and parents of each individual population were grown in greenhouse experiments in 2004, 2005, and 2006. Spikes were harvested at harvest maturity, and germination percentage at 72 h (GP72) was determined. Quantitative trait locus mapping consistently identified a large effect QTL close to the telomere region of the long arm of chromosome 5H (i.e., 5HL) in the two populations. The QTL accounted for 61 to 79% and 51 to 76% of the phenotypic variation in the Harrington/Morex and Chevron/Stander populations, respectively. Morex and Chevron contributed the dormant alleles in the two populations. The fact that Morex and Harrington both contributed nondormant alleles in different populations, and that a QTL was identified in the similar region of chromosome 5HL using the Harrington/Morex population, suggests that either linked multiple QTLs or multiple alleles for one gene controlling dormancy are present in this region. One additional small-effect QTL was identified for the two populations, respectively. The QTL identified in the Harrington/Morex population was located on chromosome 6HL near the Amy1 locus, and it explained 2% of phenotypic variation. The QTL detected in the Chevron/Stander population was on chromosome 7HS and explained 3 and 9% of the phenotypic variation, respectively, in two greenhouse experiments.

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