Glucosinolates (GS) are important sulfur-containing secondary metabolites present in a number of plant species, including Arabidopsis thaliana (L.) Heynh (Halkier and Du, 1997). More than 100 types of GS have been reported in plant species with 23 different types present in A. thaliana. The family Brassicaceae, of which A. thaliana is a member, represents a diverse group of plant species commercially important in many parts of the world. The plants produce condiment mustard; leafy, stored, processed, and picked vegetables; seed oils for margarine, salad oils, cooking oils, and industrial uses; animal fodders; and green manure crops (Williams and Hill, 1986). Isothiocyanate compounds produced in these plants through hydrolysis of GS by the enzyme myrosinase convey their unique flavor and volatile attributes, and they can also act as antioxidants and anticancer agents when consumed in the diet. The presence is GS in A. thaliana offers the opportunity to study the biochemical pathways of these compounds in a widely used model plant system. Information gained from A. thaliana may shed new light on impact of GS and their hydrolysis products in chronic disease prevention.
Glucosinolates demonstrate anticancer properties through the production of detoxification enzymes formed during hydrolysis such as quinine reductase, glutathione-S-transferase, and glucuronosyl transferase (Fahey et al., 1997; Holst and Williamson, 2004). Sulforaphane, an important GS derivative, possesses the most potent anticancer properties (Zhang et al., 1992). Sulforaphane is derived from 4-methylsulfinylbutyl GS, found in abundance in broccoli (Brassica oleracea var. Italica) heads, and functions through disruption of mitotic cell division processes, hence suppressing tumor growth. Realizing the potential use of GS in cancer treatment, several studies have evaluated broccoli accession and found significant differences for aliphatic GS (possessing specific anticancer properties) indicating that there is a potential to improve broccoli for desirable GS (Brown et al., 2002; Jeffery et al., 2003). Such genetic variation has also been reported in A. thaliana (Kliebenstein et al., 2001) as well as other vegetable Brassicas (Castro et al., 2004; Schonhof et al., 2004). However, in all cases, the genetic base and geographical range of collection of material has been narrow. Therefore, our research objectives were to acquire A. thaliana germplasm from as wide a geographic region as possible and then screen both leaf and seed tissues for GS concentrations.
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