Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola qualityBrassica napusYN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductaseThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.

Abstract

Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola quality Brassica napus YN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductase Akhov, Leonid; Ashe, Paula; Tan, Yifang; Datla, Raju; Selvaraj, Gopalan Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola quality Brassica napus YN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductase 1 Leonid Akhov, Paula Ashe, Yifang Tan, Raju Datla, and Gopalan Selvaraj Abstract: The yellow seed characteristic in Brassica napus L. is desirable because of its association with higher oil content and better quality of oil-extracted meal. YN01-429 is a yellow-seeded canola-quality germplasm developed in Canada arising from several years of research. Seed-coat pigmentation is due to oxidized proanthocyanidins (PA; condensed tannins) derived from phenylpropanoids and malonyl CoA. We found PA accumulation to be most robust in young seed coats (20 d post anthesis; dpa) of a related black-seeded line N89-53 and only very little PA in YN01-429, which also contained much less extractable phenolics. The flavonol content, however, did not show as great a difference between these two lines. Furthermore, sinapine, a product of the general phenylpropanoid metabolism, was present at comparable levels in the embryos of both lines. Dihydroflavonol reductase (DFR) activity that commits phenolics to PA synthesis was lower in YN01-429 seed coats. The results of Southern blot and in silico analyses were indicative of two copies of the DFR gene in B. napus. Both copies were functional in YN01-429, ruling out homeoallelic repression or silencing, but together they showed very low expression levels (17-fold fewer transcripts) relative to DFR activity in N89-53 seed coats. These results collectively suggest that YN01-429 differs in regulatory circuits that impact the PA synthesis branch much more than the flavonol synthesis branch in the seed coats and such circuits do not impinge upon general phenylpropanoid metabolism in the embryos.Key words: condensed tannin, dihydroflavonol reductase, flavonoids, oilseed rape, rapeseed, transparent testa. Résumé :Le jaune caractéristique des grains du Brassica napus L. est désirable, compte tenu de son association avec une haute teneur en huile et une meilleure qualité de la farine extraite de l'huile. Le YN01-429 constitue un germplasme à graine jaune de qualité canola résultant de plusieurs années de recherches. La pigmentation des téguments est attribuéeà des proanthocyanidines oxydées (PA; tannins condensés) dérivées de phénylpropanoïdes et du CoA du malonyl. Les auteurs ont trouvé une plus forte accumulation de PA chez les jeunes téguments (20 jours après l'anthèse; dpa) d'une lignée apparentéeà grains noirs N89-53 et très peu de PA chez la lignée YN01-429 qui contient à la fois beaucoup moins de phénols extractibles. Cependant, la teneur en flavonols ne montre pas autant de différences entre ces deux lignées. De plus, la sinapine, un produit du métabolisme géné...

Genome-Wide Survey of Flavonoid Biosynthesis Genes and Gene Expression Analysis between Black- and Yellow-Seeded Brassica napus

“…Moreover, much research has focused on identifying the seed pigments involved in the formation of seed coat color in B . napus (Theander et al, 1977; Marles and Gruber, 2004; Akhov et al, 2009; Qu et al, 2013). Homologous genes in the B .…”

Molecular Mapping and QTL for Expression Profiles of Flavonoid Genes in Brassica napus

“…The flavonoid biosynthesis pathways of Brassica species are much more complex than those of A. thaliana (Supplementary Figure S3); in addition to consisting of more synthesis-related genes, this pathway is also involved in multi-loci interactions, which have been shown to be involved in the formation of seed coat color in B . napus (Theander et al, 1977; Marles and Gruber, 2004; Akhov et al, 2009; Qu et al, 2013), and dozens of homologous genes in the B . napus flavonoid biosynthesis pathway have been cloned and characterized (Wei et al, 2007; Xu et al, 2007; Ni et al, 2008; Akhov et al, 2009; Auger et al, 2009; Chai et al, 2009; Lu et al, 2009; Chen et al, 2013).…”

“…napus (Theander et al, 1977; Marles and Gruber, 2004; Akhov et al, 2009; Qu et al, 2013), and dozens of homologous genes in the B . napus flavonoid biosynthesis pathway have been cloned and characterized (Wei et al, 2007; Xu et al, 2007; Ni et al, 2008; Akhov et al, 2009; Auger et al, 2009; Chai et al, 2009; Lu et al, 2009; Chen et al, 2013). Prior to this study, no comprehensive analysis of the flavonoid biosynthesis pathway had been conducted in B. napus .…”

“…Moreover, some homologs of genes involved in flavonoid biosynthesis have been cloned and characterized in B . napus (Wei et al, 2007; Xu et al, 2007; Ni et al, 2008; Akhov et al, 2009; Auger et al, 2009; Chai et al, 2009; Lu et al, 2009; Chen et al, 2013). These results provide a foundation for further studies of the molecular and regulatory mechanisms underlying seed coat color formation in B. napus .…”

Magnitude Differences in Bioactive Compounds, Chemical Functional Groups, Fatty Acid Profiles, Nutrient Degradation and Digestion, Molecular Structure, and Metabolic Characteristics of Protein in Newly Developed Yellow-Seeded and Black-Seeded Canola Lines

“…The last one is present from 150 to 300 g/kg DM, with higher levels in black-seeded varieties. 39,40 In this study, there were no significant differences in the CT content, whereas the total polyphenols tended to be lower for the yellow-than for the black-seeded varieties (6.3 vs 7.2 g/kg DM). According to Shahidi et al, 41 phenolic compounds (i.e., CT) contribute to the dark color of canola seed and their byproducts.…”