Fine-mapping of a candidate gene for web blotch resistance in Arachis hypogaea L.

Peanut(Arachis hypogaea L.)is a globally important oil crop.Web blotch is one of the most important foliar diseases affecting peanut,which results in serious yield losses worldwide.Breeding web blotch-resistant peanut varieties is the most effective and economically viable method for minimizing yield losses due to web blotch.In the current study,a bulked segregant analysis with next-generation sequencing was used to analyze an F2:3 segregating population and identify candidate loci related to web blotch resistance.Based on the fine-mapping of the candidate genomic interval using kompetitive allele-specific PCR(KASP)markers,we identified a novel web blotch resistance-related locus spanning approximately 169 kb on chromosome 16.This region included four annotated genes,of which only Arahy.35VVQ3 had a non-synonymous single nucleotide polymorphism in the coding region between the two parents.Two markers(Chr.16.12872635 and Chr.16.12966357)linked to this gene were shown to be co-segregated with the resistance of peanut web blotch by 72 randomly selected recombinant inbred lines(RIL),which could be used in marker-assisted breeding of resistant peanut varieties.

QTL mapping of quality traits in peanut using whole-genome resequencing

Oil and protein content and fatty acid composition are quality traits in peanut.Elucidating the genetic mechanisms underlying these traits may help researchers to obtain improved cultivars by molecular breeding.Whole-genome resequencing of a recombinant inbred population of 318 lines was performed to construct a high-density linkage map and identify QTL for peanut quality.The map,containing 4561 bin markers,covered 2032 c M with a mean marker density of 0.45 c M.A total of 110 QTL for oil and protein content,and fatty acid composition were mapped on the 18 peanut chromosomes.The QTL q A05.1 was detected in four environments and showed a major phenotypic effect on the contents of oil,protein,and six fatty acids.The genomic region spanned by q A05.1,corresponding to a physical interval of approximately 1.5 Mb,contains two SNPs polymorphic between the parents that could cause missense mutations.The two SNP sites were employed as KASP markers and validated using lines with extremely high and low oil contents.These sites may be useful in the marker-assisted breeding of peanut cultivars with high oil contents.

Identification of a stable major QTL for fresh-seed germination on chromosome Arahy.04 in cultivated peanut(Arachis hypogaea L.)

Fresh-seed germination(FSG)impairs peanut production,especially in areas where the peanut harvest season coincides with rainy weather.Developing FSG-resistant cultivars by molecular breeding is expected to mitigate yield loss and quality impairment caused by FSG.However,the genetic control of FSG awaits elucidation.In this study,FSG at 1,3,5,7,and 9 days post-imbibition in three environments were tested,and quantitative-trait loci(QTL)associated with FSG were mapped in a peanut recombinant inbred line population by leveraging existing high-density peanut genetic maps.Of 24 QTL identified in 13 linkage groups,qFSGA04 was a stable major QTL on linkage group 04(LG04).It was consistently detected in five germination stages and three environments.By designing and validating DNA markers in the confidence interval of qFSGA04,we identified one single-nucleotide polymorphism and one In Del closely associated with FSG that could be used as linked markers for FSG resistance in peanut breeding.