Quantitative Trait Loci Associated with Agronomic Traits of Barley (Hordeum vulgare L.)

Abstract

An amplified fragment length polymorphism (AFLP) genetic map, constructed from an F2:3 population of a cross between drought-adapted barley parent ‘Mutah’ developed in Jordan and a drought-susceptible parent ‘Er/Apm’, was established to map quantitative trait loci (QTL) controlling 14 agronomic traits. Single-marker analysis, including simple and logistic regression, and interval marker analysis, including interval mapping (IM) and composite interval mapping (CIM), were used to locate putative genes. A total of 39 AFLP loci were used to construct four linkage groups covering 544.2 cM. Results combined across the four methods of QTL analysis indicated two to six significant (P ≤ 0.05 or LOD > 2.0) marker locus-trait associations or QTL for different agronomic traits. Thirty-five putative QTL above a threshold LOD score of 2.0 were detected via CIM for the 14 studied traits. Multiple QTL were found for some traits in different regions of the same linkage group, indicating the presence of multiple genes affecting a particular trait: two QTL for plant height (PH) on lg1; two QTL for 1000-grain weight (TGW) and three QTL for PH on lg2; two QTL for fertile tiller number (FTN), two QTL for grain yield (GY), and two QTL for TGW on lg3 were detected. QTL sharing similar regions on same linkage group explained the detected significant correlation between agronomic traits. Regions around linked AFLP markers may be further saturated with co-dominant markers and studied to verify the QTL detected. Our finding should provide breeders with enhanced possibilities for the development of highly adapted barley genotypes, especially for drought conditions.