Abstract
Three RNA viruses—Cucumis melo cryptic virus (CmCV), Cucumis melo amalgavirus 1 (CmAV1), and melon necrotic spot virus (MNSV)—were identified from a melon (Cucumis melo) transcriptome dataset. CmCV has two dsRNA genome segments; dsRNA-1 is 1592 bp in size, containing a conserved RNA-dependent RNA polymerase (RdRp), and dsRNA-2 is 1715 bp in size, and encodes a coat protein (CP). The sequence alignment and phylogenetic analyses of the CmCV RdRp and CP indicated CmCV clusters with approved or putative deltapartitiviruses in well-supported monophyletic clade. The RdRp of CmCV shared an amino acid sequence identity of 60.7% with the closest RdRp of beet cryptic virus 3, and is <57% identical to other partitiviruses. CmAV1 is a nonsegmented dsRNA virus with a genome of 3424 bp, including two partially overlapping open reading frames (ORFs) encoding a putative CP and RdRp. The sequence alignment and phylogenetic analyses of CmAV1 RdRp revealed that it belongs to the genus Amalgavirus in the family Amalgaviridae. The RdRp of CmAV1 shares 57.7% of its amino acid sequence identity with the most closely related RdRp of Phalaenopsis equestris amalgavirus 1, and is <47% identical to the other reported amalgaviruses. These analyses suggest that CmCV and CmAV1 are novel species in the genera Amalgavirus and Deltapartitivirus, respectively. These findings enrich our understanding of new plant dsRNA virus species.
Highlights
Melon (Cucumis melo) is an economically important fruit crop in many areas of the world
The partitivirus isolated from C. melon was named Cucumis melo cryptic virus (CmCV)
The protein sequence sequence alignments showed that it shares the highest identity of 60.1% with the predicted RNA-dependent RNA polymerase (RdRp) of alignments showed that it shares the highest identity of 60.1% with the predicted RdRp of beet cryptic beet cryptic virus 3 (BCV3), which is in the Deltapartitiviruses genus of the Partitiviridae family
Summary
Melon (Cucumis melo) is an economically important fruit crop in many areas of the world. Amalgaviridae is a recently recognized family of double-stranded RNA viruses that contains only one genus, Amalgavirus, which includes four species of plant viruses (Blueberry latent virus, Rhododendron virus A, Southern tomato virus, and Vicia cryptic virus M) according to ICTV taxonomy (https://talk.ictvonline.org/taxonomy/). These plant amalgaviruses are monopartite, and have small dsRNA genomes of ~3.5 kbp in length containing two partially overlapping open reading frames (ORFs). Frameshift and RNA recombination simultaneously existed in the expression of the Cucumis melo amalgavirus 1 (CmAV1) genome
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