Abstract
BackgroundAlfalfa (Medicago sativa L.) is an important forage crop grown worldwide. Alfalfa is called the “queen of forage crops” due to its high forage yield and nutritional characteristics. The aim of this study was to undertake quantitative trait loci (QTL) mapping of yield and yield-related traits in an F1 population of two alfalfa varieties that differ in their yield and yield-related traits.ResultsWe constructed a high-density linkage map using single nucleotide polymorphism (SNP) markers generated by restriction-site associated DNA sequencing (RAD-seq). The linkage map contains 4346 SNP and 119 simple sequence repeat (SSR) markers, with 32 linkage groups for each parent. The average marker distances were 3.00 and 1.32 cM, with coverages of 3455 cM and 4381 cM for paternal and maternal linkage maps, respectively. Using these maps and phenotypic data, we identified a total of 21 QTL for yield and yield components, including five for yield, five for plant height, five for branch number, and six for shoot diameter. Among them, six QTL were co-located for more than one trait. Five QTL explained more than 10% of the phenotypic variation.ConclusionsWe used RAD-seq to construct a linkage map for alfalfa that greatly enhanced marker density compared to previous studies. This high-density linkage map of alfalfa is a useful reference for mapping yield-related traits. Identified yield-related loci could be used to validate their usefulness in developing markers for maker-assisted selection in breeding populations to improve yield potential in alfalfa.
Highlights
Alfalfa (Medicago sativa L.) is an important forage crop grown worldwide
Genotypic variations were significant for yield, plant height, shoot diameter, and branch number (p < 0.001) when the mixed model of genotype*years*location was used (Table 2)
Five quantitative trait loci (QTL) explained more than 10% of the phenotypic variation (PVE)
Summary
Alfalfa (Medicago sativa L.) is an important forage crop grown worldwide. Alfalfa is called the “queen of forage crops” due to its high forage yield and nutritional characteristics. The aim of this study was to undertake quantitative trait loci (QTL) mapping of yield and yield-related traits in an F1 population of two alfalfa varieties that differ in their yield and yield-related traits. Biomass yield is the most important trait for alfalfa production and increasing yield is the primary goal for improving alfalfa. Yield is a complex quantitative trait affected by the interaction of genetics and the environment (G × E). Understanding the genetic basis of yield-related traits can help increase yield in alfalfa [1]. Cultivated alfalfa is autotetraploid and its genetic composition is complex [2]. The outcrossing nature and high heterozygosity of alfalfa increase challenges in genetic analyses.
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