Project description:Seed quality traits of oilseed rape, Brassica napus (B. napus), exhibit quantitative inheritance determined by its genetic makeup and the environment via the mediation of a complex genetic architecture of hundreds to thousands of genes. Thus, instead of single gene analysis, network-based systems genomics and genetics approaches that combine genotype, phenotype, and molecular phenotypes offer a promising alternative to uncover this complex genetic architecture. In the current study, systems genetics approaches were used to explore the genetic regulation of lignin traits in B. napus seeds. Four QTL (qLignin_A09_1, qLignin_A09_2, qLignin_A09_3, and qLignin_C08) distributed on two chromosomes were identified for lignin content. The qLignin_A09_2 and qLignin_C08 loci were homologous QTL from the A and C subgenomes, respectively. Genome-wide gene regulatory network analysis identified eighty-three subnetworks (or modules); and three modules with 910 genes in total, were associated with lignin content, which was confirmed by network QTL analysis. eQTL (expression quantitative trait loci) analysis revealed four cis-eQTL genes including lignin and flavonoid pathway genes, cinnamoyl-CoA-reductase (CCR1), and TRANSPARENT TESTA genes TT4, TT6, TT8, as causal genes. The findings validated the power of systems genetics to identify causal regulatory networks and genes underlying complex traits. Moreover, this information may enable the research community to explore new breeding strategies, such as network selection or gene engineering, to rewire networks to develop climate resilience crops with better seed quality.
Project description:affy_zeawall_ril_maize - Four major QTL explaining lignin content and cell wall degradability variation have been identified in the F288 x F271 RIL progeny (Roussel et al., 2002, Maydica 47: 9-20). Gene expression has been considered as a way in identification of candidate gene underlying QTL. Five lines chosen for their allelic pattern at four main QTL were considered for expression studies, two lines with all four favorable alleles (RIL99, RIL54), two lines with the unfavorable allele at bin 6.06 QTL position (RIL39 , RIL71), and one line with the unfavorable allele at bin 9.02 QTL position (RIL118). Expression study will be investigated in ear internode at two stages emerging tassel and early silking stages with two replicates. Plants were cropped at INRA Lusignan (Vienne, France) in 2009 in a bloc design with two four-row replicates. Below-ear internodes of five representative RIL plants of one row in each replicate were harvested at the two stages and pooled. Keywords: genotype comparison, time course
Project description:affy_zeawall_ril_maize - Four major QTL explaining lignin content and cell wall degradability variation have been identified in the F288 x F271 RIL progeny (Roussel et al., 2002, Maydica 47: 9-20). Gene expression has been considered as a way in identification of candidate gene underlying QTL. Five lines chosen for their allelic pattern at four main QTL were considered for expression studies, two lines with all four favorable alleles (RIL99, RIL54), two lines with the unfavorable allele at bin 6.06 QTL position (RIL39 , RIL71), and one line with the unfavorable allele at bin 9.02 QTL position (RIL118). Expression study will be investigated in ear internode at two stages emerging tassel and early silking stages with two replicates. Plants were cropped at INRA Lusignan (Vienne, France) in 2009 in a bloc design with two four-row replicates. Below-ear internodes of five representative RIL plants of one row in each replicate were harvested at the two stages and pooled. Keywords: genotype comparison, time course 20 arrays - maize
Project description:Association Genetics can quickly and efficiently delineate regions of the genome that control traits and provide markers to accelerate breeding by marker-assisted selection. The requirements for many markers and a genome sequence to order those markers have limited its exploitation in crops. To harness this approach for use in a broad range of crops, even those with complex genomes, we developed an approach based on transcriptome sequencing to exploit markers representing variation in both gene sequences and gene expression. We term this approach Associative Transcriptomics. Applying it successfully in Brassica napus, as an example, we identified that genomic deletions including orthologues of the transcription factor controlling aliphatic glucosinolate biosynthesis in Arabidopsis thaliana, HAG1 (At5g61420), underlie two QTL for glucosinolate content of seeds.
Project description:Key messageA homoeologous non-reciprocal translocation was identified in the major QTL for seed lignin content in the low lignin line SGDH14. The lignin biosynthetic gene PAL4 was deleted. Oilseed rape is a major oil crop and a valuable protein source for animal and human nutrition. Lignin is a non-digestible, major component of the seed coat with negative effect on sensory quality, bioavailability and usage of oilseed rape's protein. Hence, seed lignin reduction is of economic and nutritional importance. In this study, the major QTL for reduced lignin content found on chromosome C05 in the DH population SGDH14 x Express 617 was further examined. SGDH14 had lower seed lignin content than Express 617. Harvested seeds from a F2 population of the same cross were additionally field tested and used for seed quality analysis. The F2 population showed a bimodal distribution for seed lignin content. F2 plants with low lignin content had thinner seed coats compared to high lignin lines. Both groups showed a dark seed colour with a slightly lighter colour in the low lignin group indicating that a low lignin content is not necessarily associated with yellow seed colour. Mapping of genomic long-reads from SGDH14 against the Express 617 genome assembly revealed a homoeologous non-reciprocal translocation (HNRT) in the confidence interval of the major QTL for lignin content. A homologous A05 region is duplicated and replaced the C05 region in SGDH14. As consequence several genes located in the C05 region were lost in SGDH14. Thus, a HNRT was identified in the major QTL region for reduced lignin content in the low lignin line SGDH14. The most promising candidate gene related to lignin biosynthesis on C05, PAL4, was deleted.
Project description:MicroRNAs and siRNAs are important regulators of plant development and seed formation, yet their population and abundance in the oil crop Brassica napus are still less understood, especially at different developmental stages and among cultivars with varied seed oil contents. Here, we systematically analyzed the small RNA expression profiles of Brassica napus seeds at early embryonic developmental stages in a high oil content and a low oil content Brassica napus cultivars, both cultured in two environments. A total of 50 conserved miRNAs and 11 new miRNAs were identified, together with some new miRNA targets. Expression analysis revealed some miRNAs with varied expression levels in different seed oil content cultivars or at different embryonic developmental stages. A large amount of 23-nt small RNAs with specific nucleotide composition preference were also identified, which may present new classes of functional small RNAs. Examination of small RNA profiles in 2 different seed oil content rapeseed culvitars at 2 locations.
Project description:UV-B radiation regulates numerous morphogenic, biochemical and physiological responses in plants, and can stimulate some responses typically associated with other abiotic and biotic stimuli, including invertebrate herbivory. Removal of UV-B from the growing environment of various plant species has been found to increase their susceptibility to consumption by invertebrate pests, however, to date, little research has been conducted to investigate the effects of UV-B on crop susceptibility to field pests. Here, we report findings from a multi-omic and genetic-based study investigating the mechanisms of UV-B-stimulated resistance of the crop, Brassica napus (oilseed rape), to herbivory from an economically important lepidopteran specialist of the Brassicaceae, Plutella xylostella (diamondback moth). The UV-B photoreceptor, UV RESISTANCE LOCUS 8 (UVR8), was not found to mediate resistance to this pest. RNA-Seq and untargeted metabolomics identified components of the sinapate/lignin biosynthetic pathway that were similarly regulated by UV-B and herbivory. Arabidopsis mutants in genes encoding two enzymes in the sinapate/lignin biosynthetic pathway, CAFFEATE O-METHYLTRANSFERASE 1 (COMT1) and ELICITOR-ACTIVATED GENE 3-2 (ELI3-2), retained UV-B-mediated resistance to P. xylostella herbivory. However, overexpression of B. napus COMT1 in Arabidopsis further reduced plant susceptibility to P. xylostella herbivory in a UV-B-dependent manner. These findings demonstrate that overexpression of a component of the sinapate/lignin biosynthetic pathway in a member of the Brassicaceae can enhance UV-B-stimulated resistance to herbivory from P. xylostella.
Project description:Salinity is a major abiotic stress that adversely affects plant growth and development. Canola (Brassica napus L.) is an important oilseed crop in the world, and its yield decreases drastically with increasing salinity. To date, little is known about the molecular mechanisms underlying its salt stress response and tolerance. This study combines physiological assays with comparative proteomics to understand how B. napus plants respond to salt stress. The changes in relative water content, electrical conductance, stomata conductance, intercellular CO2 concentration, transpiration rate, photosynthesis rate, water usage efficiency, respiration rate, chlorophyll fluorescence parameters, antioxidant enzyme activities, soluble sugar, proline and betaine in B. napus plants under 0, 50, 100, 200 and 400 mM NaCl conditions were analyzed. Proteomic profiles of B. napus plants under 100, 200 and 400 mM NaCl treatment at 7 day and 14 day were acquired using iTRAQ LC-MS/MS based quantitative proteomics. A total of 2316 proteins were identified in B. napus leaves, of which 614 proteins showed differential expression under salt stress. These proteins were mainly involved in 10 processes, of which proteins in stress and defense, metabolism and photosynthesis pathways ranked the top three. Subcellular localization analysis showed that more proteins were located in chloroplast, cytoplasm, mitochondria and nucleus. A total of 138 differentially expressed proteins were predicted to interact with each other. These results have provided a comprehensive view of the physiological and molecular processes taken place in B. napus leaves under salt stress, and revealed the molecular mechanisms underlying salt tolerance of B. napus plants.
Project description:MicroRNAs and siRNAs are important regulators of plant development and seed formation, yet their population and abundance in the oil crop Brassica napus are still less understood, especially at different developmental stages and among cultivars with varied seed oil contents. Here, we systematically analyzed the small RNA expression profiles of Brassica napus seeds at early embryonic developmental stages in a high oil content and a low oil content Brassica napus cultivars, both cultured in two environments. A total of 50 conserved miRNAs and 11 new miRNAs were identified, together with some new miRNA targets. Expression analysis revealed some miRNAs with varied expression levels in different seed oil content cultivars or at different embryonic developmental stages. A large amount of 23-nt small RNAs with specific nucleotide composition preference were also identified, which may present new classes of functional small RNAs.