summary Leptosphaeria maculans causes blackleg disease, and resistance to this fungal pathogen is an important trait in the breeding of oilseed rape. A better comprehension of the role of the
myrosinase-
glucosinolate system in this context is of great value. The present study is the first to address effects on multiple components of this complex system, including concentrations of individual
glucosinolates, product formation,
myrosinase isoform distribution and activity, and levels of
myrosinase binding proteins during the
infection process. One resistant B. napus cultivar (Maluka) and one susceptible cultivar (Westar) were compared in the investigation. Our results show that the two cultivars had the same histological distribution,
isoform expression, and activity of the
myrosinase enzymes. The
glucosinolate levels were also similar, with the exception of
glucobrassicin and
neoglucobrassicin, which were significantly lower in the resistant cultivar at 11 days post-
infection. Growth of the fungus on the plant tissues did not alter
glucosinolate levels, suggesting that L. maculans does not degrade these compounds. When the plants were starved of sulphur, and thereby depleted of
glucosinolates, no increased susceptibility was observed. Hence, we suggest that the
myrosinase-
glucosinolate system does not determine the outcome of the interaction between B. napus and L. maculans.