Abstract:
Condensed tannins (syn. proanthocyanidins, PAs) from rapeseed meal
can potentially have a negative impact on non-ruminant livestock and human
nutrition, particularly because of their ability to form indigestible, astringent
or bitter-tasting complexes with proteins. One option to overcome this
problem is the breeding of yellow-seeded rapeseed with reduced condensed
tannins in the seed coat. This might be achievable via selection of genotypes
with smaller endothelium cells and consequently a spatial reduction in
condensed tannin accumulation (seed coat structural cell mutants), or
alternatively by selection of genotypes with reduced biosynthesis of
condensed tannins (flavonoid biosynthesis mutants). Both types of
transparent testa (tt) mutants are well-characterised in Arabidopsis; however
the genetic basis of the yellow-seed trait in the polyploid genome of rapeseed
is still not completely understood.
As plant material 166 DH lines derived from a cross between an
inbred line of the black-seeded German winter oilseed rape cultivar
‘Express’ and the true-breeding, yellow-seeded line ‘1012/98’, both with 00-
seed quality were used. The genetical map was constructed using AFLP and
SSR markers. The QTL were mapped using the software PLABQTL based on
seed analyses of DH lines grown on field trials in Rauischholzhausen and
Gross-Gerau (Germany). Quality traits were measured quantitatively based
on digital reflectance values. Total PAs content was via Vanillin assay
quantified. Individual PAs and total flavonoid content were quantified via
HPLC (High Performance Liquid Chromatography) using internal standards
for quantification.
By localising quantitative trait loci (QTL) for condensed tannin
content, seed colour and other quality traits in B. napus seeds and comparing
these to the positions of promising candidate tt-genes, we hope to develop
closely-linked molecular markers for selection regarding important genes
involved in the accumulation of antinutritive compounds in rapeseed meal.
