Induced tolerance of Sclerotinia sclerotiorum to isothiocyanates and toxic volatiles from Brassica species

Abstract

The response of Sclerotinia sclerotiorum , the causal agent of stem rot of oilseed rape ( Brassica napus ), to toxic volatiles produced by the glucosinolate-myrosinase system was studied. Mycelium plugs were exposed to inoculated leaf discs of oilseed rape cultivars and two related species, black mustard ( Brassica nigra ) and white mustard ( Sinapis alba ). Growth of exposed colonies was inhibited by more than 87% compared with controls. Despite inhibition of exposed fungal colonies, the fungus continued to grow in infected tissue. Repeated exposure of the fungus to hydrated mustard powder (which contains both glucosinolates and myrosinase) or synthetic isothiocyanates (ITCs) resulted in growth inhibition decreasing from initial levels of up to 80% to insignificant levels after 2-3 days, suggesting that S. sclerotiorum has the ability to adapt to volatiles during the infection progress. This adaptation was studied by investigating induction of glutathione S-transferase-like genes identified from the S. sclerotiorum genome. Three genes, with locus numbers SS1G_07195.1, SS1G_01918.1 and SS1G_10295.1, appeared to be up-regulated following exposure of S. sclerotiorum to mustard powder or allyl ITC. A fourth gene, SS1G_07319.1, appeared to be down-regulated. In addition, glutathione S-transferase catalytic activity in crude mycelium extracts was doubled following 48 h of exposure to mustard powder volatiles. This adaptation could allow S. sclerotiorum to parasitize tissues of Brassica species despite the production of toxic metabolites.

Biofumigation with Brassica plants and its effect on the inoculum potential of Fusarium yellows of Brassica crops

“…Recently, the capability of Sclerotinia sclerotiorum to adapt to isothiocyanates and toxic metabolites from Brassica species was reported (Rahmanpour et al 2009). The possibility that certain pathogens of the plants which are used as green manure can affect amendments, causing more damage to crops has been little investigated.…”

In Vitro Activity of Glucosinolates and Their Degradation Products against Brassica-Pathogenic Bacteria and Fungi

“…Isothiocyanates (ITCs) (GHPs) and indole glucosinolate metabolites (in particular indole-3-carbinol [I3C]) are two major groups of autolytic breakdown products of GSLs. It is be-lieved that GSLs can confer resistance against pests and diseases on Brassica crops (11)(12)(13)(14)(15). Giamoustaris and Mithen (16) tested the hypothesis that B. napus varieties with high GSL levels were more resistant to Alternaria spp.…”

Study the Inhibitory Effect of Mustard Seed Powder on the Growth of Sclerotium rolfsii

“…An experiment was carried out under in vitro conditions with minor modification of the procedure of Rahmanpour et al, (2009) in two different methods. Mustard seed powder (MSP) was prepared using pestle and mortar with commercially available mustard seeds just before the experiment.…”