Fatty Acid and Transcript Profiling in Developing Seeds of Three Brassica napus Varieties

Fatty acid levels and gene expression profiles for selected genes associated with the synthesis of fatty acids (FA), triacylglycerol, and oil body proteins were examined in three oilseed rape (Brassica napus) cultivars, Bronowski, Westar, and Q2 during seed development. These three cultivars are used for new cultivar development in our spring canola breeding program. The results showed that the seed oil content of Bronowski, Q2, and Westar was 39.0, 40.1, and 40.6%, respectively. During the 20 to 40 day period of seed development, cultivars had varying levels of palmitic, stearic, oleic, linoleic, α-linolenic, eicosenioc, and erucic acid. In general, the percentage of each FA did not shift much during seed development. Gene expression among the three cultivars was similar from 10 to 40 days after flowering (DAF). The few exceptions were that expression of FAD3 was higher in Q2 at 15 DAF and Q2 and Westar at 20 and 25 DAF, FAE1 was higher in Bronowski than in Westar at 20 DAF, and cruciferin was higher in Bronowski and Westar than Q2 at 20 DAF. The correlation for gene expression against DAF for each genotype was examined. The data support a common trend in gene expression among the three cultivars with gene expression tending to decrease over time; except for LPAAT, which tended to increase. The correlation between the level of FAs and expression of genes by genotype was also examined. The results showed that there was no general trend; rather correlations seem to depend on the genotype.