Identification of QTLs Associated with Oil Content in a High-Oil Brassica napus Cultivar and Construction of a High-Density Consensus Map for QTLs Comparison in B. napus

Abstract

Increasing seed oil content is one of the most important goals in breeding of rapeseed (B. napus L.). To dissect the genetic basis of oil content in B. napus, a large and new double haploid (DH) population containing 348 lines was obtained from a cross between ‘KenC-8’ and ‘N53-2’, two varieties with >10% difference in seed oil content, and this population was named the KN DH population. A genetic linkage map consisting of 403 markers was constructed, which covered a total length of 1783.9 cM with an average marker interval of 4.4 cM. The KN DH population was phenotyped in eight natural environments and subjected to quantitative trait loci (QTL) analysis for oil content. A total of 63 identified QTLs explaining 2.64–17.88% of the phenotypic variation were identified, and these QTLs were further integrated into 24 consensus QTLs located on 11 chromosomes using meta-analysis. A high-density consensus map with 1335 marker loci was constructed by combining the KN DH map with seven other published maps based on the common markers. Of the 24 consensus QTLs in the KN DH population, 14 were new QTLs including five new QTLs in A genome and nine in C genome. The analysis revealed that a larger population with significant differences in oil content gave a higher power detecting new QTLs for oil content, and the construction of the consensus map provided a new clue for comparing the QTLs detected in different populations. These findings enriched our knowledge of QTLs for oil content and should be a potential in marker-assisted breeding of B. napus.

Identification of quantitative trait loci associated with oil content and development of near isogenic lines for stableqOC-A10inBrasscia napusL.

“…Recently, our markers were applied in two studies on QTL mapping for oil content (Sun et al 2012;Wang et al 2013). Wang et al (2013) a QTL are designated using the trait name initials followed by "year", "location name initial", "population" and "linkage group number", which was followed by "−1,−2 : : : " to distinguish QTL on the same linkage group. e R 2 percentage of trait variance explained by the QTL.…”

“…Some efforts have been made in quantitative trait loci (QTL) mapping for oil content in rapeseed (Ecke et al 1995;Burns et al 2003;Zhao et al 2005Zhao et al , 2006Zhao et al , 2008Zhao et al , 2012Delourme et al 2006;Qiu et al 2006;Sun et al 2012;Wang et al 2013;Jiang et al 2014) that shed light on dissecting the genetic mechanism of oil content and provide a theoretical basis to develop effective breeding methods. Most of this research has been carried out using doubled haploid (DH) populations, including DY ('Darmor-bzh' × 'Yudal') and RNSL ('Rapid' × 'NSL96/25') (Delourme et al 2006), TN ('Tapidor' × 'Ningyou7') (Qiu et al 2006;Jiang et al 2014), SG ('Sollux' × 'Gaoyou') (Zhao et al 2005(Zhao et al , 2006(Zhao et al , 2008(Zhao et al , 2012, Z5 ('ZY036' × '51070') (Sun et al 2012), and KN ('KenC-8' × 'N53-2') populations.…”

“…Most of these studies exhibited only a slight difference in oil content between two parents. Recently, some studies have used parental lines with significant differences in oil content (>10%) (Sun et al 2012;Wang et al 2013), which was useful to detect QTL. These studies showed that QTL for oil content were distributed on 18 of 19 B. napus chromosomes, except chromosome C4 (Ecke et al 1995;Zhao et al 2005Zhao et al , 2006Zhao et al , 2008Zhao et al , 2012Delourme et al 2006;Qiu et al 2006;Sun et al 2012;Wang et al 2013;Jiang et al 2014).…”

“…Recently, some studies have used parental lines with significant differences in oil content (>10%) (Sun et al 2012;Wang et al 2013), which was useful to detect QTL. These studies showed that QTL for oil content were distributed on 18 of 19 B. napus chromosomes, except chromosome C4 (Ecke et al 1995;Zhao et al 2005Zhao et al , 2006Zhao et al , 2008Zhao et al , 2012Delourme et al 2006;Qiu et al 2006;Sun et al 2012;Wang et al 2013;Jiang et al 2014). The number of QTL detected varied from three (Ecke et al 1995) to 27 (Chen et al 2010) and explained phenotypic variation ranging from 1.2% (Delourme et al 2006) to more than 20% (Chen et al 2010;Sun et al 2012).…”

Detection of quantitative trait loci for kernel oil and protein concentration in a B73 and Zheng58 maize cross

“…Wang et al (2010) used composite interval mapping and mapped 1-6 QTLs for grain oil and starch content in two populations under different environments. Wang et al (2013) used a double haploid population and identified a total of 63 QTLs for oil content. Although large QTLs were detected in those studies, others have reported contrasting results, including QTL number, distribution, and genetic effect.…”