The Biosynthesis of Glucosinolates: Insights, Inconsistencies, and Unknowns

Glucosinolates (GSLs) and their hydrolysis products (GHPs) are of great interest within the scientific community. Isothiocyanates (ITCs) are one type of hydrolysis product that have efficacy against some forms of cancer and prevention of some neurodegenerative disorders. They can also have potent effects upon pests and diseases of crops, and give rise to the characteristic tastes and flavours of many commonly consumed Brassicales crops. The genetic mechanisms underlying GSL biosynthesis and regulation of GHPs are well elucidated in the model organism Arabidopsis thaliana, and research over the last fifteen years has also greatly expanded knowledge within Brassica spp. There are of course many hundreds of GSL-producing species within the Brassicales order, with potentially very different and/or advanced mechanisms of GSL biosynthesis, metabolism, and catabolism. This paper summarises the current understanding of GSL biosynthesis, and highlights areas of exploration beyond the ‘Arabidopsis and Brassica bubble’ of GSL research. Novel GSLs, and the gene encoding proteins that regulate their biosynthetic pathways, could greatly enhance our knowledge of Brassicales phytochemistry, evolution, and natural history if given more attention.