Exploring RNA virus diversity in Metarhizium spp

• Ano de defesa: 2023
• Autor(a) principal: Oliveira, Cauê Neves
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Microbiologia Agrícola
• Palavras-chave em Português: Micovírus; Metarhizium; Vírus de RNA de cadeia dupla; Fungos entomopatogênicos; Pragas - Controle biológico; Microbiologia Agrícola
• Link de acesso: https://locus.ufv.br/handle/123456789/32572; https://doi.org/10.47328/ufvbbt.2024.261

Viruses are ubiquitous acellular organisms since there is evidence of them hosting any living cell in all kingdoms. Mycoviruses are characterized by infecting fungi. The International Committee on Taxonomy of Virus (ICTV) recently recognized 29 families with representatives of mycoviruses. Most of these families have an RNA genome, and only one has a circular ssDNA genome. The non-retroviral RNA viruses are sorted into three Baltimore groups. Group III is characterized by having a dsRNA genome, while groups IV and V correspond to a ssRNA positive and negative sense, respectively. The unique hallmark gene in these three groups is RNA-dependent RNA polymerase (RdRp). This protein is responsible for viral genome replication and is conserved in all groups. Moreover, mycovirus infection can change the host phenotype. Most of the time, these changes are related to modification of their host pathogenic trait. For example, hypovirulent-associated mycoviruses are characterized by reducing the aggressiveness of phytopathogenic fungi by slowing down their mycelial growth and sporulation rate, as well as downregulating pathogenic genes. On the other hand, hypervirulent-associated mycoviruses are characterized by promoting mycelial growth and sporulation rate and upregulating host pathogenic genes. Therefore, mycoviruses are a more eco-friendly alternative to pest-management strategies than the use of chemical compounds related to ecosystem harm. Hypovirulent-associated mycovirus can be used to control the incidence of phytopathogenic fungi, and hypervirulent-associated mycovirus can increase the efficacy of mycopesticides. Studies already demonstrate that hypervirulent-associated mycoviruses hosting entomopathogenic fungi (EPF) can increase their potential to control insect pests. This work used two approaches to identify novel mycoviruses infecting the EPF in the genus Metarhizium. The first strategy was carried out by the total nucleic acid extraction of a Metarhizium robertsii isolate SCJAN-21.11 followed by identifying and sequencing the dsRNA viral genome. As we know, we report the first case of a polymycovirus hosting a Metarhizium in Brazil. This polymycovirus has at least three dsRNA genome segments. Each segment encodes only one ORF representing the RdRp, a hypothetical protein, and a methyltransferase. The RdRp aminoacid phylogenetic analyses revealed that this mycovirus represents a new species, and we attempted to call it Polymycovirus mineiro. In the second strategy, we used a database with 77 viral family-level profile Hidden Markov Models (pHMM) to look for RdRp-like sequences in the public RNAseq data available on NCBI tagged as “Metarhizium.” The pHMM is a statistical model to identify sequence patterns. As a result, we could identify 42 virus-like sequences in approximately 20% of the analyzed data. In conclusion, this study helps elucidate the virosphere in Metarhizium genera and investigate the possibility of using mycovirus as a biocontrol agent. Keywords: Mycovirus; Biocontrol; Entomopathogenic fungi; Metarhizium