Transcriptome Analysis of Cryphonectria parasitica Infected With Cryphonectria hypovirus 1 (CHV1) Reveals Distinct Genes Related to Fungal Metabolites, Virulence, Antiviral RNA-Silencing, and Their Regulation

Abstract

Comprehensive transcriptome analysis was conducted to elucidate the molecular basis of the interaction between chestnut blight fungus, Cryphonectria parasitica, and single-stranded RNA (ssRNA) mycovirus Cryphonectria hypovirus 1 (CHV1), using RNAsequencing (RNA-seq). A total of 1,023 differentially expressed genes (DEGs) were affected by CHV1 infection, of which 753 DEGs were upregulated and 270 DEGs were downregulated. Significant correlations in qRT-PCR analysis of 20 randomly selected DEGs and agreement with previously characterized marker genes validated our RNAseq analysis as representing global transcriptional profiling of virus-free and-infected isogenic strains of C. parasitica. Gene Ontology (GO) analysis of DEGs indicated that "cellular aromatic compound metabolic process" and "transport" were the two most enriched components in the "biological process." In addition, "cytoplasm" was the most enriched term in the "cellular component" and "nucleotide binding" and "cation binding" were the two most enriched terms in the "molecular function" category. These results suggested that altered expression of genes encoding numerous intracellular proteins due to hypoviral infection resulted in changes in specific metabolic processes as well as transport processes. Kyoto Encyclopedia of Genes and Genomes function analysis demonstrated that pathways for "biosynthesis of other secondary metabolites," "amino acid metabolism," "carbohydrate metabolism," and "translation" were enriched among the DEGs in C. parasitica. These results demonstrate that hypoviral infection resulted in massive but specific changes in primary and secondary metabolism, of which antiviral fungal metabolites were highly induced. The results of this study provide further insights into the mechanism of fungal gene regulation by CHV1 at the transcriptome level.

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

“…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). The virus has been used over decades as a naturally occurring or artificially released biocontrol agent against chestnut blight in Europe (e.g., Diamandis et al, 2014; Heiniger & Rigling, 2009).…”

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

“…An example of how mycoviruses can impact on fungal metabolisms is well-represented by the interaction between the model host Cryphonectria parasitica (the causal agent of chestnut canker) and its virus Cryphonectria hypovirus 1. In more detail, it was demonstrated that the mycovirus infection produce a wide metabolic reprogramming of its host, modifying the whole primary and secondary metabolisms [58,64]. The same results were also achieved in other species, where several studies demonstrated that mycoviruses are also able to modify the production of effectors and secondary metabo-lites [12,13,65].…”

Deoxynivalenol Biosynthesis in Fusarium pseudograminearum Significantly Repressed by a Megabirnavirus

“…In C. parasitica , “biosynthesis of other secondary metabolites”, “amino acid metabolism”, “carbohydrate metabolism”, and “translation” were enriched among the DEGs after CHV1 infection, demonstrating that virus infection resulted in massive but specific changes in primary and secondary metabolism. Some of the highly induced metabolites played key roles in the growth, development and pathogenicity of fungi [ 52 ]. The complex interaction between leucine metabolism and the global regulator of mycotoxin biosynthesis, TRI6, and virulence in F. graminearum has been explored [ 53 ].…”