A single base change in the Bn-FAE1.1 gene in the A genome and a two-base
deletion in the Bn-FAE1.2 gene in the C genome produce the nearly zero
content of erucic acid observed in canola. A BAC clone anchoring
Bn-FAE1.1 from a B. rapa BAC library and a BAC clone anchoring Bn-FAE1.2
from a B. oleracea BAC library were used in this research. After
sequencing the gene flanking regions, it was found that the dissimilarity
of the flanking sequences of these two FAE1 homologs facilitated the
design of genome specific primers that could amplify the corresponding
genome in allotetraploid B. napus. The two-base deletion in the C genome
gene was detected as a sequence characterized sequence region (SCAR)
marker. To increase the throughput, one genome specific primer was
labeled with four fluorescence dyes and combined with 20 different
primers to produce PCR products with different fragment sizes.
Eventually, a super pool of 80 samples was detected simultaneously,
making it possible to analyze over half a million of samples per day
using a medium capacity ABI 3100 Genetic Analyzer. This dramatically
reduces the cost of marker detection. The single base change in the
Bn-FAE1.1 gene was detected as single nucleotide polymorphic (SNP) marker
with an ABI SNaPshot kit. A multiplexing primer set was designed by
adding a polyT to the 5' primer end to increase SNP detection throughput
through sample pooling. These multiplexed high throughput molecular
markers have been successfully implemented in our canola/rapeseed
breeding programs.