Update on glucosinolate metabolism and transport

Glucosinolates are secondary plant metabolites found mainly in the order Ca pparales. Tissue disruption allows rapid enzymatic degradation of glucosino lates by specific thioglucosidases, denoted myrosinases. Within the last fe w years, significant progresses in our understanding of glucosinolate biosy nthesis and degradation have been achieved. In particular, the Arabidopsis thaliana genome-sequencing project has accelerated the identification and c haracterization of genes involved in the glucosinolate metabolism. More evi dence has accumulated for the hypothesis that the glucosinolate-myrosinase system has evolved from the prevalent system of cyanogenic glucosides and c orresponding O-beta -glucosidases. Glucosinolates have been shown to be tak en up by a specific carrier system and transported by phloem. The de novo b iosynthesis, degradation and transport of glucosinolates may constitute a d elicately regulated dynamic diagram, through which various physiological fu nctions are fulfilled. There is a rising interest in controlling the level of glucosinolates in crops to improve pest resistance and nutritional value . Genes identified in Arabidopsis thaliana will provide important tools to initiate molecular strategies to modulate the quantity and quality of gluco sinolates in a tissue-specific manner in closely related Brassica crops. Th is review summarizes current knowledge on glucosinolate biosynthesis, degra dation and mobilization, and provides a comprehensive discussion and update on the regulation, physiological functions and genetic engineering of gluc osinolate metabolism and transport. (C) 2001 Editions scientifiques et medi cales Elsevier SAS.