Identification and Complete Genome Sequence of an Alternavirus from a Pathogenic Fungus, Fusarium nanum, Collected by Air Sampling

Abstract

In this study, fungal spores were collected from the air, and mycelium was grown in Petri dishes containing potato dextrose agar medium in the lab. Based on the morphological and molecular characteristics, the fungus was identified as Fusarium nanum. A new double-stranded RNA (dsRNA) mycovirus was isolated from the mycelia of F. nanum and tentatively named Fusarium nanum alternavirus 1 (FnAV1). The complete genome sequence of FnAV1 was obtained by Illumina sequencing, followed by Sanger sequencing and the rapid amplification of cDNA ends (RACE) of the 5′ and 3′ ends. FnAV1 is composed of three dsRNA segments: dsRNA1 (3,546 nt) encodes RdRp, dsRNA2 (2,511 nt) encodes a hypothetical protein, and dsRNA3 encodes the coat protein (2,484 nt). The multiple alignments, along with phylogenetic analysis based on the RdRp (dsRNA1) and coat protein (dsRNA3) amino acid sequences, suggest that FnAV1 clusters with other members of the newly proposed family Alternaviridae, has high identities with Fusarium incarnatum alternavirus 1 (FiAV1), and might be a new strain isolated from a different fungal host, F. nanum. This is the first report of a mycovirus from the mycelial culture of F. nanum, which was obtained from spores collected at a 12-m altitude via air sampling. This suggests that the airborne spores could carry the mycovirus for long-distance movement and dissemination to new locations. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Keywords

• airborne spores
• Alternaviridae
• complete genome
• mycovirus