Abstract
Leaf is the main organ of photosynthesis, which significantly impacts crop yield. A high-density linkage map containing 1894 single nucleotide polymorphism (SNP) and 68 simple sequence repeats (SSR) markers was used to identify quantitative trait locus (QTL) for flag leaf length (FLL), second leaf length (SLL), third leaf length (TLL), fourth leaf length (FOLL), flag leaf area (FLA), second leaf area (SLA), third leaf area (TLA) and fourth leaf area (FOLA). In total, 57 QTLs underlying the top four leaf length and area traits were identified and mapped on chromosome 2H, 3H, 4H and 7H. Individual QTL accounted for 5.17% to 37.11% of the phenotypic variation in 2015 and 2016. A major stable QTL qFLL2-2 close to the marker 2HL_25536047 was identified on the long arm of chromosome 2H. The most important QTL clustered region at M_256210_824 - 2HL_23335246 on chromosome 2H was associated with FLL, SLL, FLA and SLA and explained high phenotypic variation. These findings provide genetic basis for improving the leaf morphology of barley. In addition, our results suggested that the top four leaves were significantly positively correlated with plant height and some yield-related traits.
Highlights
Barley (Hordeum vulgare L.), as one of the earliest domesticated and most important cereal crops for humanity, is widely used for food, feed and malting
Our group has constructed a high density of linkage map containing 1962 single nucleotide polymorphism (SNP) and simple sequence repeats (SSR) markers using a barley doubled haploid (DH) population[21], which has previously been used for identifying quantitative trait locus (QTL) underlying yield-related traits[22], physiological traits of flag leaf including net photosynthesis rate[18] and mapping a new dwarf gene btwd[123]
Leaf is the main organ of photosynthesis, and the top two leaves produce over 80% of the net photosynthesis product during grain filling, the flag leaf, which assimilates most of the light energy and converts it to 41–43% of the carbohydrates for kernel filling[3,30]
Summary
Barley (Hordeum vulgare L.), as one of the earliest domesticated and most important cereal crops for humanity, is widely used for food, feed and malting. Leaf size and shape are regarded as important traits determining photosynthesis capability and grain yield[5,6,7]. Our group has constructed a high density of linkage map containing 1962 SNP and SSR markers using a barley DH population[21], which has previously been used for identifying QTLs underlying yield-related traits[22], physiological traits of flag leaf including net photosynthesis rate[18] and mapping a new dwarf gene btwd[123]. The objectives of this study were to use this high density of linkage map to identify QTL associated with the topmost four leaf length and area traits; and to reveal the relationships among the topmost four leaves, plant height and yield-related traits. The detected QTLs and their closely linked markers can be used for marker-assisted selection (MAS) in barley breeding
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