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detected during commercial use of the synthetic-ITC generating pesticide metham sodium
(Matthiessen et al ., 2004; Gimsing & Kirkegaard, 2006). A broader IPM (Integrated Pest
Management) approach to biofumigation as a component of disease control strategies,
assisted by new soil microbial ecology techniques is providing insights to optimize the
ITC and non-ITC related benefi ts of biofumigants, although success is by no means
universal (Hartz et al ., 2005; Njoroge et al ., 2008). This chapter reviews the fundamental
processes underlying the biofumigation concept, considers recent progress in refi ning
approaches for successful commercial adoption and provides some case studies to
highlight opportunities and challenges for further development of the concept.
9.2
The glucosinolate-myrosinase system
GSLs are a class of sulfur compounds occurring as secondary metabolites almost
exclusively in plants belonging to the Order Capparales, which includes the Brassicaceae
(Fenwick et al ., 1983; Fahey et al ., 2001). GSLs are characterized by a common chemi-
cal entity (
-thioglucoside with a sulphonated oxime moiety) with a variable chemical
side-chain [R] that distinguishes individual types (Mithen, 2001) (Figure 9.1). The 120
β
Glucosinolate
Hydrolysis products
Figure 9.1 Glucosinolates are hydrolyzed by the myrosinase enzyme when intact tissues of
glucosinolate-containing plants are disrupted to release a range of hydrolysis products. The isothiocya-
nates are considered the most bioactive. The structure of the organic side-chain [R] varies in different
glucosinolates and is retained in the isothiocyanates and infl uences their biological activity. The [R] group
structure of some common aliphatic and aromatic isothiocyanates are shown to illustrate the diversity.
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