The impact of parasitism on resource allocation in a fungal host: the case of Cryphonectria parasitica and its mycovirus, Cryphonectria Hypovirus 1

Abstract

Parasites are known to profoundly affect resource allocation in their host. In order to investigate the effects of Cryphonectria Hypovirus 1 (CHV1) on the life‐history traits of its fungal host Cryphonectria parasitica, an infection matrix was completed with the cross‐infection of six fungal isolates by six different viruses. Mycelial growth, asexual sporulation, and spore size were measured in the 36 combinations, for which horizontal and vertical transmission of the viruses was also assessed. As expected by life‐history theory, a significant negative correlation was found between host somatic growth and asexual reproduction in virus‐free isolates. Interestingly this trade‐off was found to be positive in infected isolates, illustrating the profound changes in host resource allocation induced by CHV1 infection. A significant and positive relationship was also found in infected isolates between vertical transmission and somatic growth. This last relationship suggests that in this system, high levels of virulence could be detrimental to the vertical transmission of the parasite. Those results underscore the interest of studying host–parasite interaction within the life‐history theory framework, which might permit a more accurate understanding of the nature of the modifications triggered by parasite infection on host biology.

Vertical Transmission of Fusarium circinatum Mitoviruses FcMV1 and FcMV2-2 via Microconidia

“…These results contrast with those obtained for C. parasitica [30,36] in which vertical transmission was influenced by the fungal isolate and viral strain. This could be explained by the low genetic diversity of the Spanish population of F. circinatum due to its recent introduction and low rate of sexual reproduction [45,46] as almost all clonal isolates are expected to behave similarly and have similar transmission probabilities.…”

“…This result is not consistent with previous findings using a quantitative genetics approach, in which an association between the fitness of the host and its vertically transmitted parasites was expected [35,36]. It is likely that the persistence of either horizontally or vertically transmitted infections are not favored if infection produced by mycoviruses leads to a reduction of host fitness and hence has negative implications for a fungal host population [37].…”

Temporal changes in pathogen diversity in a perennial plant–pathogen–hyperparasite system

“…CHV1, which belongs to the family Hypoviridae, is a positive‐strand RNA virus located in the cytoplasm of C. parasitica (Choi & Nuss, 1992). The virus significantly reduces virulence, growth and sporulation of the infected fungal strain, subsequently leading to recovery of infected chestnut trees (Anagnostakis, 1982; Brusini et al, 2017; Rigling & Prospero, 2018). On a molecular level, CHV1 has been found to significantly alter expression of genes in C. parasitica associated with virulence, primary and secondary metabolism, as well as carbohydrate metabolization (Chun et al, 2020).…”

Aspergillus Goes Viral: Ecological Insights from the Geographical Distribution of the Mycovirome within an Aspergillus flavus Population and Its Possible Correlation with Aflatoxin Biosynthesis

“…As already well-established for the human virome, which has been correlated to various disease and physiological states [53][54][55][56], the identification and characterization of the mycovirome associated with a specific fungal population could provide a more detailed comprehension of the ecological relationships. It also represents, at the same time, an emergent tool to clarify some specific biological functions which could be linked to a viral infection and which can in turn impact both the fungal metabolism and the intra/interspecific interactions [10,57,58].…”

“…Indeed, during the last decades, some biological processes, including virulence and sporulation, which are fundamental for both the colonization of the environment and the ecological fitness of the fungus, were demonstrated to be influenced by the presence of mycoviruses in many fungi. Attenuation of virulence, alteration of colonies' morphology, reduction of conidia production, modification of accumulation of secondary metabolites (SMs), and decrease of growth rate in their hosts are the most commonly detected negative effects [9][10][11][12][13]. Although the role of fungi-associated viruses still remains largely unknown and the relevant literature is scarce in comparison to the number of papers produced on the plant viruses, their capacity in attenuating the pathogenicity of the fungal host and/or in modulating the biosynthesis of toxic metabolites is of great interest to the scientific community.…”