AbstractsBiology & Animal Science

Rapeseed (Brassica napus L.) is an important oilseed crop. Its oil is used for human consumption, as green fuel (biodiesel), and in the chemical and pharmaceutical industry. The cake and meal, residues of oil pressing and extraction, are used as valuable components for feeding animals. Seed metabolism and root traits are two important components of seed quality and yield, respectively, in B. napus. Both are controlled by complex genetic mechanisms. The aim of this study was to develop and use novel high throughput DNA sequencing techniques, on one hand, to investigate digital gene expression (DGE) of gene networks responsible for important seed quality traits, and on the other hand to use DGE along with high-throughput phenotyping of root architectural traits in a rapeseed population for marker trait association. Two B. napus black seeded winter genotypes were selected to investigate their transcriptome during seed development by DGE: Express617 which is a 00-quality cultivar with high lignin content and V8, which has high seed erucic acid and glucosinolate (GSL) contents but moderate levels of seed lignin, another antinutritive compound in the seed meal. Early stages of seed development from 2-28 dap showed high correlation and a great variation was observed in later stages and the seed maturation phase in the two genotypes. Based on their previously known differential phenotypes for total GSL and lignin, differential expression of genes involved in GSL metabolic and phenylpropanoid/lignin biosynthesis pathway was observed in the MapMan metabolic pathway annotator during seven seed developmental time points (2-84 days after pollination). A total of 58 genes were annotated to the phenylpropanoid pathway specifically directed to lignin biosynthesis, while 34 genes were detected from the GSL metabolic pathway. Expression pattern of genes involved in lignin biosynthesis showed up-regulation in Express617 during the seed maturation phase from 42 until 70 dap. Expression of six MYB family transcription factors (MYB4, 32, 58, 61, 63 and 85) were detected which are responsible for activation of monolignol pathway genes by coordinating binding motifs corresponding to their AC-rich elements. AC elements are present in the promoters of most monolignol pathway genes, including PAL, 4CL, C3H, CCoAOMT, CCR and CAD, and many of these genes showed different expression patterns between the two genotypes corresponding to their differences in lignin compounds. Similarly, several genes known to be involved in the GSL metabolic pathway are considered as candidates for controlling GSL contents in rape seeds to reduce total glucosinolates in rapeseed meal. In this study, expression of 34 genes was observed were involved in GSL amino acid side chain elongation, core structure formation from amino acid moiety, secondary modification and degradation enzymes. Expression of transcription factors OBP2/DOF1.1 and the MYB family (MYB34, 28 and 51) which are known to be responsible for GSL pathway regulation were also detected during seed…