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

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.q SPA07.1 on chromosome A07 explained up to 31.7%of phenotypic variation,and q SPA08.2 on chromosome A08 explained up to 10.8%.Favorable alleles of q SPA07.1 and q SPA08.2 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.q SPA07.1 and q SPA08.2 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 q SPA07.1 and q SPA08.2.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.

Integrated genetic linkage map of cultivated peanut by three RIL populations

High-density and precise genetic linkage map is fundamental to detect quantitative trait locus (QTL) of agronomic and quality related traits in cultivated peanut (Arachis hypogaea L.). In this study, three linkage maps from three RIL (recombinant inbred line)populations were used to construct an integrated map. A total of 2,069 SSR and transposon markers were anchored on the high-density integrated map which covered 2,231.53 cM with 20 linkage groups. Totally, 92 QTLs correlating with pod length (PL), pod width (PW), hundred pods weight (HPW) and plant height (PH) from above RIL populations were mapped on it. Seven intervals were found to harbor QTLs controlling the same traits in different populations,including one for PL, three for PW, two for HPW, and one for PH. Besides, QTLs controlling different traits in different populations were found to be overlapped in four intervals.Interval on A05 contains 17 QTLs for different traits from two RIL populations. New markers were added to these intervals to detect QTLs with narrow confidential intervals.Results obtained in this study may facilitate future genomic researches such as QTL study, fine mapping, positional cloning and marker-assisted selection (MAS) in peanut.