Detection and characterisation of two novel vitiviruses infecting Actinidia

Abstract

Two co-infecting novel vitiviruses from Actinidia chinensis were identified from mechanically inoculated Nicotiana occidentalis. Both virus genomes were sequenced and share 64% nucleotide identity. Their overall structure is typical of vitiviruses, with five open reading frames (ORFs) and a polyadenylated 3' end. Open reading frame 4 (ORF4) encodes the coat protein, the most conserved gene of the vitiviruses, in which they share 75% amino acid identity, 61-68% with grapevine virus B, 55-59% with grapevine virus A, and 37-42% with grapevine virus E. Based on the molecular criteria for species demarcation in the family Betaflexiviridae, these are two novel viruses, tentatively named Actinidia virus A and Actinidia virus B.

Occurrence and molecular characterization of Actinidia virus C (AcVC), a novel vitivirus infecting kiwifruit (Actinidia spp.) in China

“…The complete genome sequence of the new virus isolate, named AcVC‐Zhouzhi, consists of 7,668 nucleotides, not including the poly‐(A) sequence. Its overall genome structure is typical of vitiviruses, with five open reading frames (ORFs) and a polyadenylated 3′ terminus (Martelli et al , 1997; Blouin et al , 2012). Regarding the genome structure of vitiviruses, ORF1 encodes a large RdRp; ORF2 encodes a hypothetical protein whose function remains unknown; ORF3 encodes the movement protein (MP); ORF4 encodes the coat protein (CP); and ORF5 encodes the RNA‐binding protein (RBP).…”

“…Like other viruses, vitiviruses induce symptoms in the infected kiwifruit plants and the symptoms vary with type of virus, infection status, and plant species/cultivar. For example, A. chinensis 'Hort16A' plants showed light mottle symptoms after inoculation with AcVB (Blouin et al , 2012). Coinfection with AcVA and AcVB induced symptoms of mottle, veinal chlorosis, and chlorotic ringspots in the plants of A. chinensis Hort16A, while the same infection caused symptoms of mottle and veinal chlorosis in the plants of A. deliciosa ‘Hayward’ (Blouin et al , 2012) .…”

“…For example, A. chinensis 'Hort16A' plants showed light mottle symptoms after inoculation with AcVB (Blouin et al , 2012). Coinfection with AcVA and AcVB induced symptoms of mottle, veinal chlorosis, and chlorotic ringspots in the plants of A. chinensis Hort16A, while the same infection caused symptoms of mottle and veinal chlorosis in the plants of A. deliciosa ‘Hayward’ (Blouin et al , 2012) . In the present study, obvious symptoms of chlorotic spots and wrinkles were observed on the leaves of AcVC‐infected kiwifruit A. deliciosa 'Xuxiang' grown in the field.…”

“…The first virus naturally infecting kiwifruit was reported in 2003 (Clover et al , 2003) and only three kiwifruit viruses had been reported by 2010 (Clover et al , 2003; Chavan et al , 2009; 2013). Recent studies have shown that at least 17 viruses have been detected in natural infections of kiwifruit, including cucumber necrosis virus (CNV), radish mosaic virus (RMV), cherry leaf roll virus (CLRV), cucumber mosaic virus (CMV), citrus leaf blotch virus (CLBV), potato virus X (PVX), pelargonium zonate spot virus (PZSV), tomato necrotic spot associated virus (TNSaV), tomato zonate spot virus (TZSV), turnip vein clearing virus (TVCV), Actinidia virus A (AcVA), Actinidia virus B (AcVB), Actinidia virus X (AVX), Actinidia virus 1 (AcV‐1), Actinidia seed‐borne latent virus (ASbLV) and Actinidia chlorotic ringspot‐associated emaravirus (AcCRaV) (Pearson et al , 2011; Blouin et al , 2012; 2013; 2018; Chavan et al , 2012; 2013; James and Phelan, 2016; Wang et al , 2016; Zheng et al , 2017; Veerakone et al , 2018; Zhao et al , 2019).…”

“…and Actinidia chlorotic ringspot-associated emaravirus (AcCRaV) (Pearson et al, 2011;Blouin et al, 2012;Chavan et al, 2012;James and Phelan, 2016;Wang et al, 2016;Zheng et al, 2017;Veerakone et al, 2018;Zhao et al, 2019).…”