Stable major QTL on chromosomes A07 and A08 increase shelling percentage in peanut (Arachis hypogaea L.)

Abstract

Peanut is a major oilseed and food legume. Shelling percentage (SP), closely associated with seed yield, is a trait whose improvement is a major goal of peanut breeding. In this study, a mapping population (Xuhua 13 × Zhonghua 6) was used to map quantitative trait loci (QTL) controlling SP in four environments. Two stable major QTL for SP were mapped on both SSR- and SNP-based genetic maps. qSPA07.1 on chromosome A07 explained up to 31.7% of phenotypic variation, and qSPA08.2 on chromosome A08 explained up to 10.8%. Favorable alleles of qSPA07.1 and qSPA08.2 were derived from the female and male parents, respectively. Eight recombinant inbred lines (RILs) carrying both favorable alleles showed superiority in SP over the two parents in all environmental trials. A combination of the two favorable alleles using the linked markers was verified to increase SP by ∼5% in the RIL population and by ∼3% SP in diverse peanut cultivars. qSPA07.1 and qSPA08.2 were delimited to respectively a 0.73-Mb interval harboring 96 genes and a 3.93-Mb interval harboring 238 genes. Respectively five and eight genes with high expression in pods, including enzymes and transcription factors, were assigned as candidate genes for qSPA07.1 and qSPA08.2. These consistent major QTL provide an opportunity for fine mapping of genes controlling SP, and the linked markers may be useful for genetic improvement of SP in peanut.

Keywords

• Peanut
• Shelling percentage
• QTL mapping
• Genomic region
• Candidate genes
• InDel marker