RESUMO
A novel mycovirus was identified infecting the phytopathogenic fungus Microdochium albescens. The characterized dsRNA segment, corresponding to the replicative intermediate of the mitovirus genome, is 2,562 base pairs (bp) in length, with an A+U content of 62.3%. A single open reading frame (ORF) was identified, encoding a putative RNA-dependent RNA polymerase (RdRp) of 706 amino acids. Phylogenetic analysis showed that this virus should be classified as a member of a new species in the genus Mitovirus, family Mitoviridae, for which we propose the name "Mitovirus gaucho". This is the first report of a mycovirus infecting the phytopathogenic fungus M. albescens, the causative agent of leaf scald on rice in Brazil.
Assuntos
Ascomicetos , Micovírus , Vírus de RNA , Ascomicetos/genética , Micovírus/genética , Genoma Viral , Fases de Leitura Aberta , Filogenia , Doenças das Plantas , Vírus de RNA/genética , RNA de Cadeia Dupla , RNA Viral/genéticaRESUMO
The Bemisia tabaci is a polyphagous insect and a successful vector of plant viruses. B. tabaci is a species complex and in Brazil native species from the New World (NW) group, as well as the invasive species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) were reported. For better understanding the distribution of the different species four years after the Mediterranean species invasion in Brazil, whiteflies were collected from 237 locations throughout the country between the years of 2013 and 2017, species were identified and the facultative endosymbionts detected. The survey revealed that MEAM1 was the prevalent species found on major crops across Brazil. It is the only species present in North, Northwestern and Central Brazil and was associated with virus-infected plants. MED was found in five States from Southeast to South regions, infesting mainly ornamental plants and was not associated with virus-infected plants. The prevalent endosymbionts identified in MEAM1 were Hamiltonella and Rickettsia; and the mtCOI analysis revealed low genetic diversity for MEAM1. In contrast, several different endosymbionts were identified in MED including Hamiltonella, Rickettsia, Wolbachia and Arsenophonus; and two distinct genetic groups were found based on the mtCOI analysis. Monitoring the distribution of the whiteflies species in Brazil is essential for proper management of this pest.
Assuntos
Alphaproteobacteria/isolamento & purificação , Gammaproteobacteria/isolamento & purificação , Hemípteros/classificação , Hemípteros/crescimento & desenvolvimento , Espécies Introduzidas , Filogeografia , Simbiose , Alphaproteobacteria/classificação , Alphaproteobacteria/genética , Animais , Brasil , Complexo IV da Cadeia de Transporte de Elétrons/genética , Gammaproteobacteria/classificação , Gammaproteobacteria/genética , Variação Genética , Hemípteros/genética , Hemípteros/microbiologiaRESUMO
BACKGROUND: The whitefly Bemisia tabaci is a major cosmopolitan pest and comprises a complex of more than 36 cryptic species that cause serious damage to agricultural crops worldwide. In this study, the Mediterranean species of B. tabaci, formerly known as Q biotype, was identified for the first time in Brazil. RESULTS: Adult B. tabaci were collected from different localities and hosts from Rio Grande do Sul, the southernmost state of the country that borders Uruguay and Argentina. Partial sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene indicated that B. tabaci MED species appears to be restricted to the province of Barra do Quaraí, infesting Capsicum annuum cultivated in greenhouses and Ipomoea batatas in open fields. The partial mtCOI sequences obtained shared 100% nucleotide identity with reference sequences for the Q biotype reported from Uruguay. The secondary endosymbionts Hamiltonella and Cardinium were detected by PCR in the new identified MED species from Brazil, similarly to the Q biotype from Uruguay. CONCLUSION: Our results indicate the presence of the MED species in Brazil. The close monitoring of this new identified species in the southern region of Brazil is essential to avoid its geographical expansion to more important agricultural areas in the country.