Fungal and oomycete pathogens and heavy metals: an inglorious couple in the environment

Authors: GAJEWSKA, JOANNA - Adam Mickiewicz University; FLORYSZAK-WIECZOREK, JOLANTA - Poznan University Of Life Sciences; SOBIESZCZUK-NOWICKA, EWA - Adam Mickiewicz University; Mattoo, Autar; PLOCIENNIK, ARTUR - Adam Mickiewicz University; ARASIMOWICZ-JELONEK, MAGDALENA - Adam Mickiewicz University

Submitted to: IMA Fungus
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2022
Publication Date: 4/25/2022
Citation: Gajewska, J., Floryszak-Wieczorek, J., Sobieszczuk-Nowicka, E., Mattoo, A.K., Plociennik, A., Arasimowicz-Jelonek, M. 2022. Fungal and oomycete pathogens and heavy metals: an inglorious couple in the environment. IMA Fungus. https://doi.org/10.1186/s43008-022-00092-4.
DOI: https://doi.org/10.1186/s43008-022-00092-4

Interpretive Summary: Heavy metals (HMs) in the environment adversely target growth, morphology, viability and physiology including nitro-oxidative stress of eukaryotic pathogens. Low amounts of HMs promote growth and cause sporulation resembling hormetic stimulation. Since hormesis may play an important role in the adaptation of pathogens to a variety of host microenvironments that exhibit different sets of chemical challenges, the understanding of molecular mechanisms of the phenomenon is important to seek. This review focuses on various aspects of HM-contaminated environment that can affect pathogen capability to infect host organisms. Considering the possible huge biotechnological potential of fungal microorganisms, research focus on such pathogenic fungi have the potential for large scale bioremediation processes. There is a need to characterize the chemistry and environmental fates of the metabolites produced during fungal bioremediation. Thus, broadening the knowledge on HM contamination of the microbial environment is critical. This review is important to plant biologists, microbiologists and students working on pathogens in relation to contaminated soils, and scientists studying fungal bioremediation.

Technical Abstract: Heavy metal (HM) contamination of the environment is a major problem worldwide. The rate of global deposition of HMs in soil has dramatically increased over the past two centuries and there of facilitated their rapid accumulation also in living systems. Although the effects of HMs on plants, animals and humans have been extensively studied, yet little is known about their effects on the (patho)biology of the microorganisms belonging to a unique group of filamentous eukaryotic pathogens, i.e., fungi and oomycetes. Much of the literature concerning mainly model species has revealed that HM stress affects their hyphal growth, morphology, and sporulation. Toxicity at cellular level leads to disturbance of redox homeostasis manifested by the formation of nitro-oxidative intermediates and to the induction of antioxidant machinery. Despite such adverse effects, published data is indicative of the fact that fungal and oomycete pathogens have a relatively high tolerance to HMs in comparison to other groups of microbes such as bacteria. Likely, these pathogens may harbor a network of detoxification mechanisms that ensure their survival in a highly HM-polluted (micro)habitat. Such a network may include extracellular HMs immobilization, biosorption to cell wall, and/or their intracellular sequestration to proteins or other ligands. HMs may also induce a hormesis-like phenomenon allowing the pathogens to maintain or even increase fitness against chemical challenges. Different scenarios linking HMs stress and modification of the microorganisms pathogenicity are disscused in this review.