Abstract
BackgroundThe objective of this research was to map quantitative trait loci (QTLs) of multiple traits of breeding importance in pea (Pisum sativum L.). Three recombinant inbred line (RIL) populations, PR-02 (Orb x CDC Striker), PR-07 (Carerra x CDC Striker) and PR-15 (1–2347-144 x CDC Meadow) were phenotyped for agronomic and seed quality traits under field conditions over multiple environments in Saskatchewan, Canada. The mapping populations were genotyped using genotyping-by-sequencing (GBS) method for simultaneous single nucleotide polymorphism (SNP) discovery and construction of high-density linkage maps.ResultsAfter filtering for read depth, segregation distortion, and missing values, 2234, 3389 and 3541 single nucleotide polymorphism (SNP) markers identified by GBS in PR-02, PR-07 and PR-15, respectively, were used for construction of genetic linkage maps. Genetic linkage groups were assigned by anchoring to SNP markers previously positioned on these linkage maps. PR-02, PR-07 and PR-15 genetic maps represented 527, 675 and 609 non-redundant loci, and cover map distances of 951.9, 1008.8 and 914.2 cM, respectively. Based on phenotyping of the three mapping populations in multiple environments, 375 QTLs were identified for important traits including days to flowering, days to maturity, lodging resistance, Mycosphaerella blight resistance, seed weight, grain yield, acid and neutral detergent fiber concentration, seed starch concentration, seed shape, seed dimpling, and concentration of seed iron, selenium and zinc. Of all the QTLs identified, the most significant in terms of explained percentage of maximum phenotypic variance (PVmax) and occurrence in multiple environments were the QTLs for days to flowering (PVmax = 47.9%), plant height (PVmax = 65.1%), lodging resistance (PVmax = 35.3%), grain yield (PVmax = 54.2%), seed iron concentration (PVmax = 27.4%), and seed zinc concentration (PVmax = 43.2%).ConclusionWe have identified highly significant and reproducible QTLs for several agronomic and seed quality traits of breeding importance in pea. The QTLs identified will be the basis for fine mapping candidate genes, while some of the markers linked to the highly significant QTLs are useful for immediate breeding applications.
Highlights
The objective of this research was to map quantitative trait loci (QTLs) of multiple traits of breeding importance in pea (Pisum sativum L.)
Plant materials Three recombinant inbred populations (RILs) of pea, namely, PR-02 derived from the cross Orb/CDC Striker, PR-07 derived from the cross Carrera/CDC Striker, and PR-15 derived from the cross 1–2347-144/CDC Meadow, each consisting of 94 individuals were used for phenotyping and genotyping
Genetic linkage mapping Of the > 25,000 single nucleotide polymorphism (SNP) identified by GBS in each RIL population, after filtering for read depth of 5, percentage of missing values as less than 15%, Chi-square value of > 0.1 probability for segregation distortion, 2066, 3023, and 3444 SNPs were used to construct genetic linkage maps of PR-02, PR-07 and PR-15, respectively
Summary
The objective of this research was to map quantitative trait loci (QTLs) of multiple traits of breeding importance in pea (Pisum sativum L.). Molecular markers including single nucleotide polymorphisms (SNPs), simple sequence repeats (SSRs) and other markers have been used to study the genetic variation within Pisum. These markers were useful for the construction of linkage maps to provide frameworks for identification of quantitative trait loci (QTLs) and trait-linked markers related to many important traits including resistance to diseases such as powdery mildew, Fusarium wilt, Ascochyta blight and rust, lodging resistance, time to flowering, seed mineral and protein concentration (reviewed by [2,3,4,5]), and validation of some of the identified QTLs Development of high density genetic linkage maps is important for QTL identification and marker-assisted breeding
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