The glucosinolates-myrosinase system

Glucosinolates are the main secondary metabolites found in cruciferous crops. Their presence is made known to us whenever we eat cruciferous vegetable and salad crops as they degrade immediately upon tissue damage to release a small number of products, of which isothiocyanates ( mustard oils ) are the most well known. The chemical structure and concentration to which humans are exposed can be considered a consequence of three processes First, the synthesis and accumulation of the glucosinolate molecule in the crop plants, which is dependent upon both genetic and environmental factors, second the hydrolysis of the glucosinolates to produce isothiocyanates and other products, which can 

Methylsulphinylpropyl (iberin) broccoli, some Brussels sprouts and cabbages 

2- Propenyl (allyl) mustards, cabbages, some Brussels sprouts 

3- Butenyl Brussel sprouts, Chinese cabbages, bok choi, turnip greens, swede 

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PONTOPPIDAN, B., Studies of the Glucosinolate-Myrosinase System in Relation to Insect Herbivory on Oilseed Rape (Brassica napus) and in Arabidopsis thaliana., PhD thesis, Swedish University of Agricultural Sciences., Agraria, 2001. 

BRIDGES, M, JONES, A.M.E., BONES, A.M., HODGSON, C., COLE, R, BARTLET, E WALLSGROVE, R., KARAPAPA, V.K., WATTS, N., ROSSITER, J.T., Spatial organization of the glucosinolate-myrosinase system in Brassica specialist aphids is similar to that of the host plant., Proc. R. Soc. Lond. Ser. B-Biol. Sci, 2002, 269, 187-191. 

J.T., Spatial organization of the glucosinolate-myrosinase system in brassica... 

Clearly, the way in which the myrosinase-glucosinolate system operates in B. brassicae and L. erysimi is very different from the cyanogenic glucoside system in other insects, and its organization so far appears to be unique in the insect world, yet draws a direct parallel with the plant system. 

There are two rich sources of organosulphur compounds from plants (1) Alliaceae family containing alliin-alliinase system and (2) Cruciferae (Brassicacae) family e.g. Brassica juncea, Wasabia japonica (wasabi), Armoracia rusticam (horseradish) and Brassica oleracea (cauliflower) containing glucosinolate-myrosinase (Mithen 2006). A number of sulphur-containing compounds can be derived from these plants through the action of myrosinase and alliinase enzymes. 

Bones, A. M. and Rossiter, J. T. (1996). The myrosinase-glucosinolate system, its organisation and biochemistry. Physiologia Plantarum 97 194-208. 

Andreasson, E., Wretblad, S., Graner, G, Wu, X.M., Zhang, J.M, Dixelius, C., Rask, L., Meijer, J. The myrosinase-glucosinolate system in the interaction between Leptosphaeria maculans and Brassica napus. Mol Plant Pathol 2001 21 281-286. 

Arabidopsis thaliana (L.) Heynh. is today the most useful model system in plant research, and in order to be able to generalize results from this species, it is important to investigate its special characteristics, such as the myrosinase-glucosinolate system. In this chapter, we present the localization of the myrosinase-glucosinolate system in Arabidopsis and other plants and discuss in vivo degradation and transport of glucosinolates. 

The myrosinase-glucosinolate system occurs in 16 plant families.17 It is likely that this system evolved from the ancient (and near ubiquitous) cyanogenic glycosides. This hypothesis is supported by the similarity, in sequence and structure, of glucosinolate biosynthetic enzymes and the hydrolytic enzymes (myrosinase or p-glucosidase).18 The biochemistry of these metabolites also indicates a convincing evolutionary relationship.19 Furthermore, on the basis of robust phylogenetic trees,... 

Kliebenstein DJ, Pedersen D, Mitchell-Olds T (2002) Comparative analysis of insect resistance QTL and QTL controlling the myrosinase/ glucosinolate system in Arabidopsis thaliana. Genetics 161 325-332. 

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