Lipid regulation in Brassica napus: spatiotemporal studies to enhance our understanding

Brassica napus (and related Brassica species) is the world's third most important oil crop, providing around 13% of the total global vegetable oil. There are two basic types of cultivars - those with significant erucate being used for renewable chemicals, while low-erucate varieties (the majority) supply the food industry. B. napus oil is particularly enriched in oleate but also contains a nutritionally desirable ratio of n-3 to n-6 polyunsaturated fatty acids. In this review we note the overall importance of rapeseed oil and describe in detail how it is biosynthesised, mainly through the classic Kennedy pathway with additional reactions. We then discuss very recent advances in our understanding of how biosynthesis is regulated and spatiotemporal aspects of oil accumulation in the crop. Both biotic and abiotic environmental effects on B.napus yields are then summarized. Recently, MALDI-MSI has been developed for lipids and its ability to reveal spatial and temporal differences in lipid species distribution has proven especially useful. The technique has exposed unsuspected details in metabolism as well as confirming other reported aspects of lipid biochemistry. The similar, but not identical, lipid metabolism in Arabidopsis has facilitated many of the advances in B. napus and it is anticipated that the momentum of new discoveries will continue to be rapid and significant.