title: Molecular Mapping and QTL for Expression Profiles of Flavonoid Genes inBrassica napus.
abstract: Flavonoids are secondary metabolites that are extensively distributed in the plant kingdom and contribute to seed coat color formation in rapeseed. To decipher the genetic networks underlying flavonoid biosynthesis in rapeseed, we constructed a high-density genetic linkage map with 1089 polymorphic loci (including 464 SSR loci, 97 RAPD loci, 451 SRAP loci, and 75 IBP loci) using recombinant inbred lines (RILs). The map consists of 19 linkage groups and covers 2775 cM of theB. napusgenome with an average distance of 2.54 cM between adjacent markers. We then performed expression quantitative trait locus (eQTL) analysis to detect transcript-level variation of 18 flavonoid biosynthesis pathway genes in the seeds of the 94 RILs. In total, 72 eQTLs were detected and found to be distributed among 15 different linkage groups that account for 4.11% to 52.70% of the phenotypic variance atrributed to each eQTL. Using a genetical genomics approach, four eQTL hotspots together harboring 28 eQTLs associated with 18 genes were found on chromosomes A03, A09, and C08 and had high levels of synteny with genome sequences ofA. thalianaand Brassica species. Associated with thetrans-eQTL hotspots on chromosomes A03, A09, and C08 were 5, 17, and 1 genes encoding transcription factors, suggesting that these genes have essential roles in the flavonoid biosynthesis pathway. Importantly,bZIP25, which is expressed specifically in seeds,MYC1, which controls flavonoid biosynthesis, and the R2R3-type geneMYB51, which is involved in the synthesis of secondary metabolites, were associated with the eQTL hotspots, and these genes might thus be involved in different flavonoid biosynthesis pathways in rapeseed. Hence, further studies of the functions of these genes will provide insight into the regulatory mechanism underlying flavonoid biosynthesis, and lay the foundation for elaborating the molecular mechanism of seed coat color formation inB. napus.
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Cunmin
authors.initials: C
authors.lastname: Qu
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Huiyan
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Botany and Plant Pathology, Purdue University West Lafayette, IN, USA.
authors.forename: Fuyou
authors.initials: F
authors.lastname: Fu
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Jianglian
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Liezhao
authors.initials: L
authors.lastname: Liu
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Xinfu
authors.initials: X
authors.lastname: Xu
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Lu
authors.affiliation: Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest UniversityChongqing, China; Engineering Research Center of South Upland Agriculture of Ministry of Education, Southwest UniversityChongqing, China.
authors.forename: Jia-Na
authors.initials: JN
authors.lastname: Li
keywords: Brassica napus; QTLs; expression profiles; flavonoid genes; genetic map