Dataset Information

Associative transcriptomics study dissects the genetic architecture of seed glucosinolate content in Brassica napus.

ABSTRACT: Breeding new varieties with low seed glucosinolate (GS) concentrations has long been a prime target in Brassica napus. In this study, a novel association mapping methodology termed 'associative transcriptomics' (AT) was applied to a panel of 101 B. napus lines to define genetic regions and also candidate genes controlling total seed GS contents. Over 100,000 informative single-nucleotide polymorphisms (SNPs) and gene expression markers (GEMs) were developed for AT analysis, which led to the identification of 10 SNP and 7 GEM association peaks. Within these peaks, 26 genes were inferred to be involved in GS biosynthesis. A weighted gene co-expression network analysis provided additional 40 candidate genes. The transcript abundance in leaves of two candidate genes, BnaA.GTR2a located on chromosome A2 and BnaC.HAG3b on C9, was correlated with seed GS content, explaining 18.8 and 16.8% of phenotypic variation, respectively. Resequencing of genomic regions revealed six new SNPs in BnaA.GTR2a and four insertions or deletions in BnaC.HAG3b. These deletion polymorphisms were then successfully converted into polymerase chain reaction-based diagnostic markers that can, due to high linkage disequilibrium observed in these regions of the genome, be used for marker-assisted breeding for low seed GS lines.

SUBMITTER: Lu G

PROVIDER: S-EPMC4263295 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Associative transcriptomics study dissects the genetic architecture of seed glucosinolate content in Brassica napus.

Lu Guangyuan G Harper Andrea L AL Trick Martin M Morgan Colin C Fraser Fiona F O'Neill Carmel C Bancroft Ian I

DNA research : an international journal for rapid publication of reports on genes and genomes 20140715 6

Breeding new varieties with low seed glucosinolate (GS) concentrations has long been a prime target in Brassica napus. In this study, a novel association mapping methodology termed 'associative transcriptomics' (AT) was applied to a panel of 101 B. napus lines to define genetic regions and also candidate genes controlling total seed GS contents. Over 100,000 informative single-nucleotide polymorphisms (SNPs) and gene expression markers (GEMs) were developed for AT analysis, which led to the iden ...[more]

PMID: 25030463

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Project description:Glucosinolates (GSLs) are a major class of secondary metabolites. The content of seed GSL is largely regulated by environments in rapeseed (Brassica napus). However, the genetic control of seed GSL content responsible for environment in B. napus has been poorly understood. In the current study, a doubled haploid (DH) population from a cross between winter and semi-winter lines of rapeseed was grown in two distinct eco-environments, Germany and China, to evaluate the eco-environment effect and dissect the quantitative trait loci (QTL) responsible for environment for seed GSL in rapeseed. The deviation value of GSL content between eco-environments (GSLE) was calculated for each line in the DH population and the QTLs for GSLE were detected. GSLE ranged from -46.90 to 36.13 μmol g-1 meal in the DH population, suggesting the prominent eco-environmental effects for seed GSL in rapeseed. Four QTLs for GSLE were identified on chromosomes A04, A06, and A09 explaining 4.70∼9.93% of the phenotypic variation. Comparison of QTLs of seed GSL content between different eco-environments found three QTLs for GSL on A02 from 37.6 to 45.4 cM, A04 from 0 to 17.2 cM, and A09 from 67.0 to 98.6 cM exhibited significant difference of QTL effect between the German and Chinese eco-environments (P < 0.01), indicating the environment sensibility of these loci on seed GSL content. Moreover, flowering time (FT), an important environment adaptation trait in plant, was also investigated in this study. Comparative QTL analysis among GSLE, GSL, and FT revealed that three regions on chromosomes A02, A04, and A09 not only exhibited significant differences in QTL effect between Germany and China, but also co-located with the QTL intervals of GSLE and FT. Our results revealed that most of the GSL loci can influence GSL accumulation under different eco-environments, whereas the three QTL intervals on A02, A04, and A09 might be sensitive to the eco-environments for seed GSL content.

Project description:BackgroundTocopherols are important antioxidants in vegetable oils; when present as vitamin E, tocopherols are an essential nutrient for humans and livestock. Rapeseed (Brassica napus L, AACC, 2 n = 38) is one of the most important oil crops and a major source of tocopherols. Although the tocopherol biosynthetic pathway has been well elucidated in the model photosynthetic organisms Arabidopsis thaliana and Synechocystis sp. PCC6803, knowledge about the genetic basis of tocopherol biosynthesis in seeds of rapeseed is scant. This project was carried out to dissect the genetic basis of seed tocopherol content and composition in rapeseed through quantitative trait loci (QTL) detection, genome-wide association analysis, and homologous gene mapping.Methodology/principal findingsWe used a segregating Tapidor × Ningyou7 doubled haploid (TNDH) population, its reconstructed F(2) (RC-F(2)) population, and a panel of 142 rapeseed accessions (association panel). Genetic effects mainly contributed to phenotypic variations in tocopherol content and composition; environmental effects were also identified. Thirty-three unique QTL were detected for tocopherol content and composition in TNDH and RC-F(2) populations. Of these, seven QTL co-localized with candidate sequences associated with tocopherol biosynthesis through in silico and linkage mapping. Several near-isogenic lines carrying introgressions from the parent with higher tocopherol content showed highly increased tocopherol content compared with the recurrent parent. Genome-wide association analysis was performed with 142 B. napus accessions. Sixty-one loci were significantly associated with tocopherol content and composition, 11 of which were localized within the confidence intervals of tocopherol QTL.Conclusions/significanceThis joint QTL, candidate gene, and association mapping study sheds light on the genetic basis of seed tocopherol biosynthesis in rapeseed. The sequences presented here may be used for marker-assisted selection of oilseed rape lines with superior tocopherol content and composition.

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Associative transcriptomics study dissects the genetic architecture of seed glucosinolate content in Brassica napus.

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Associative transcriptomics study dissects the genetic architecture of seed glucosinolate content in Brassica napus.

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