Marine Oomycetes of the Genus Halophytophthora Harbor Viruses Related to Bunyaviruses.

Leticia Botella,Marilia Horta Jung,Thomas Jung,Cristiana Maia,Milica Raco,Josef Janoušek

doi:10.3389/fmicb.2020.01467

Abstract

We investigated the incidence of RNA viruses in a collection of Halophytophthora spp. from estuarine ecosystems in southern Portugal. The first approach to detect the presence of viruses was based on the occurrence of dsRNA, typically considered as a viral molecule in plants and fungi. Two dsRNA-banding patterns (∼7 and 9 kb) were observed in seven of 73 Halophytophthora isolates tested (9.6%). Consequently, two dsRNA-hosting isolates were chosen to perform stranded RNA sequencing for de novo virus sequence assembly. A total of eight putative novel virus species with genomic affinities to members of the order Bunyavirales were detected and their full-length RdRp gene characterized by RACE. Based on the direct partial amplification of their RdRp gene by RT-PCR multiple viral infections occur in both isolates selected. Likewise, the screening of those viruses in the whole collection of Halophytophthora isolates showed that their occurrence is limited to one single Halophytophthora species. To our knowledge, this is the first report demonstrating the presence of negative (−) ssRNA viruses in marine oomycetes.

Highlights

Halophytophthora species are fungal-like oomycetes with similar morphology and life cycles as members from their well-known plant pathogenic sister genus Phytophthora (Sullivan et al, 2018)
All Halophytophthora isolates studied were collected from seven localities in southern Portugal (Table 1) using an in situ baiting technique (Jung et al, 2017a)
Traditional dsRNA extraction procedures were used to identify the potential presence of viruses in a collection of Halophytophthora spp. isolates from estuarine ecosystems in southern Portugal

Summary

Introduction

Halophytophthora species are fungal-like oomycetes with similar morphology and life cycles as members from their well-known plant pathogenic sister genus Phytophthora (Sullivan et al, 2018). Most Halophytophthora species live in brackish and salt water habitats and have been traditionally described as saprophytes playing a key role as decomposers mainly in mangrove ecosystems (Newell and Fell, 1992, 1997). Halophytophthora zostera was shown to restrict the viability of Z. marina seeds

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Results

Conclusion