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

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DOIResolve DOI: http://doi.org/10.1139/B09-036
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TypeArticle
Journal titleBotany
Volume87
Issue9
Pages616625; # of pages: 10
Subjectcondensed tannin; dihydroflavonol reductase; flavonoids; oilseed rape; rapeseed; transparent testa
AbstractThe 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.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Plant Biotechnology Institute
Peer reviewedYes
NRC number50124
NPARC number16907875
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Record identifier8378f9b5-ed14-45ed-aac5-bb17d2c4b800
Record created2011-02-22
Record modified2016-05-09
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