Changes in the expression of a gene involved in cell wall integrity are related to mycotoxin production in filamentous fungi in food

DELGADO, JOSUÉ; DA CRUZ CABRAL, LUCÍA; FODI, SIHEM

Freising

Workshop; International Commission on Food Mycology Workshop; 2019

Spoilage and mycotoxigenic fungi are able to colonise a wide range of ecological niches including soil, plants and foods. External conditions and antifungal compounds may trigger different signal cascades within the fungal cell that culminate in changes at the transcriptional level, leading to the production of compatible solutes to enable the enzyme systems to function under the environmental conditions. It has been suggested that these compounds may act as stressors and provoke an increase of mycotoxin production. Fungi have different intracellular pathways that help them coping with challenging external conditions. Among them, the cell wall integrity pathway (CWI) is activated in response to cell wall stresses due to different food-related environments. So far, little is known about the relationship between the activation of CWI pathway and mycotoxin production by important economic filamentous fungi commonly found in various cereals and fruits. The objectives of this work were to: a) evaluate effect of external conditions (temperature, water activity) and antifungal compounds (fungicides, biocontrol agents) on growth, mycotoxin production and changes in the expression of the Rho1 gene, one of the main regulators of CWI pathway by some Alternaria species and A. ochraceus in model systems based on wheat, tomato and raisins; b) analyse the relationship between Rho1 gene expression and both the growth and mycotoxin production by the target filamentous fungi. Results showed that temperatures, water activity and the nature of the fungicide have different influence on both growth and mycotoxin (ochratoxin A, alternariol, alternariol monomethyl ether and tenuazonic acid) production. In addition, it has been shown that changes in the CWI pathway and the accumulation of ochratoxin A and Alternaria spp. mycotoxins seem to be related under specific environmental conditions. These findings will be useful in developing new strategies to efficiently control toxigenic fungus spoilage in cereals and fruits.