Glucosinolate-derived isothiocyanates impact mitochondrial function in fungal cells and elicit an oxidative stress response necessary for growth recovery

Abstract

Glucosinolates are brassicaceous secondary metabolites that have long been considered as chemical shields against pathogen invasion. Isothiocyanates (ITCs), are glucosinolate-breakdown products that have negative effects on the growth of various fungal species. We explored the mechanism by which ITCs could cause fungal cell death using Alternaria brassicicola, a specialist Brassica pathogens, as model organism. Exposure of the fungus to ICTs led to a decreased oxygen consumption rate, intracellular accumulation of reactive oxygen species (ROS) and mitochondrial-membrane depolarization. We also found that two major regulators of the response to oxidative stress, i.e., the MAP kinase AbHog1 and the transcription factor AbAP1, were activated in the presence of ICTs. Once activated by ICT-derived ROS, AbAP1 was found to promote the expression of different oxidative-response genes. This response might play a significant role in the protection of the fungus against ICTs as mutants deficient in AbHog1 or AbAP1 were found to be hypersensitive to these metabolites. Moreover, the loss of these genes was accompanied by a significant decrease in aggressiveness on Brassica. We suggest that the robust protection response against ICT-derived oxidative stress might be a key adaptation mechanism for successful infection of host plants by Brassicaceae-specialist necrotrophs like A. brassicicola.

Use of Botanicals to Suppress Different Stages of the Life Cycle of Fusarium graminearum

“…Furthermore, Quiles et al (2015) investigated the potential of mustard-based botanicals to reduce aflatoxin contamination of wheat tortillas by Aspergillus parasiticus and observed that the gaseous allyl ITC from oriental mustard was more effective than p-HBITC from white mustard; however, substantial reduction in aflatoxin occurred with either treatment. Calmes et al (2015) studied the mechanisms by which ITCs could cause fungal cell death using Alternaria brassicicola as a model organism. The authors demonstrated that exposure to these compounds led to reduced oxygen consumption rate, intracellular accumulation of reactive oxygen species, and mitochondrialmembrane depolarization.…”

Biosynthesis and bioactivity of glucosinolates and their production in plant in vitro cultures

“…In addition, isothiocyanates were able to decrease the ATP synthesis in yeast by inhibiting the connection between the electron transport chain and oxidative phosphorylation (Vig et al 2009). Calmes et al (2015) found that isothiocyanates induced oxidative stress in Alternaria brassicicola, a Brassicaceae-specific fungus, decreasing the oxygen consumption rate, increasing intracellular accumulation of ROS and causing mitochondrial-membrane depolarization.…”

Steam radish sprout (Raphanus sativus L.): active substances, antioxidant activities and non‐targeted metabolomics analysis

“…Plant-based diets are widely thought to reduce the risk of aging-related diseases (Baenas et al, 2016;Baenas et al, 2017a;Baenas et al, 2017b), which is largely attributed to the activities of their bioactive substances such as polyphenols, vitamin C and other endogenous metabolites (Calmes et al, 2015;Ma et al, 2018;Gillespie et al, 2018). Moreover, plants tend to bring about antioxidant effects owing to the presence of some antioxidant enzymes such as superoxide dismutase (SOD).…”