Epidemiology of Toxigenic Fungi and Mycotoxins in Plant Pathology: Virulence and Plant Responses

Dear Colleagues,

Mycotoxins are harmful secondary metabolites, responsible for different human and animal disorders, produced by several filamentous fungi, mainly belonging to the Alternaria, Aspergillus, Fusarium, and Penicillium genera. At the worldwide level, the most commonly investigated are alternariol and its derivatives, aflatoxins, fumonisins and trichothecenes, and ochratoxins, respectively.

The contamination of crops worldwide is highly variable and strictly depends form geographical areas and environmental conditions. Due to the continuously evolving climatic conditions, a correct approach to collect significant epidemiological data on the mycotoxins and related fungi occurrence is a key aspect to better assess the risk related to mycotoxins.

Together with the risk they represent in food safety, many mycotoxins can play a key function in plant–pathogen interactions. Indeed, mycotoxins target different essential cellular processes in plants, acting as key virulence factors and enhancing host colonization and disease development. Their biological activity reflects a dynamic interplay between fungal pathogenicity mechanisms and plant defence responses, triggering adverse outcomes such as reduced growth or cell death. For instance, trichothecenes, inhibiting eukaryotic protein synthesis, cause necrosis and tissue collapse that facilitate fungal invasion; fumonisins, interfering with sphingolipid metabolism, compromise membrane integrity and immunity-related signalling. Mycotoxin biosynthesis is regulated by complex gene pathways integrating environmental and host-derived signals. They can also act as effectors, manipulating plant physiology and therefore favouring fungal infection. Some of them interfere with hormonal, enzymatic, or receptor-mediated signalling linked to plant immune response. For instance, some Alternaria species express this strategy, producing host-specific toxins that induce programmed cell death in susceptible cultivars via gene-for-gene interactions, illustrating the co-evolutionary dynamics between hosts and pathogens.

Plants, however, possess sophisticated detoxification and defence systems. Upon exposure, they activate enzymes such as glutathione S-transferases, cytochrome P450 monooxygenases, and UDP-glucosyltransferases, which convert or sequester toxins into less harmful forms. Additional responses include the rapid reactive oxygen species (ROS) accumulation, cell wall reinforcement, phytoalexin synthesis, and induction of pathogenesis-related proteins. Notably, sublethal toxin concentrations may act as defence elicitors, priming the immune system for enhanced resistance.

To date, the crucial role of some mycotoxins, such as trichothecenes and alternariol, in the fungal infection process and in host-plant interaction, is well known, while for other ones has been poorly elucidated.

This Special Issue aims to gain new insights into the interaction between mycotoxigenic fungi and their host plants. We encourage submissions of original research articles, reviews, and perspectives focusing on the critical role of mycotoxins in plant pathology, highlighting their contribution to pathogen virulence and the multiple responses elicited in host plants. This focus aims to advance understanding of the molecular, biochemical, and physiological interactions supporting plant-mycotoxin dynamics, which are pivotal for developing innovative strategies to mitigate plant disease and enhance crop resilience. The additional goal of this Special Issue is to bridge the existing knowledge gaps in this field, with particular emphasis on the poorly studied mycotoxins. Authors are encouraged to contribute high-quality manuscripts that provide novel insight into pathogenic mechanisms, plant defence pathways, and applied approaches for plant disease management.

Dr. Antonio Moretti
Dr. Stefania Somma
Dr. Mario Masiello
Guest Editors

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