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Mealybug wilt of pineapple (MWP) is the most important and complex viral disease affecting pineapple worldwide. High-throughput sequencing was conducted to characterize a new virus identified only in symptomatic pineapple plants and tentatively named pineapple mealybug wilt-associated virus 6 (PMWaV-6). Data analyses revealed a genome of 17,854 nucleotides with an organization resembling members of the genus Ampelovirus, family Closteroviridae. Encoded proteins shared sequence identity with the corresponding proteins of grapevine leafroll-associated virus 3, blackberry vein banding-associated virus, and PMWaV-2. The present study reports the discovery of PMWaV-6, a putative and distinct new member of the genus Ampelovirus, subgroup I, its potential involvement in MWP, and the development of PMWaV-6-specific RT-PCR assays to detect and monitor this virus in field samples. [ABSTRACT FROM AUTHOR]

Three novel viruses were detected from Japanese persimmon 'Reigyoku' (Diospyros kaki), which grows poorly when top-grafted onto some interstocks. The genomic characterization and the phylogenetic analysis of these viruses indicated that they are likely new members of the genera Ampelovirus, Polerovirus, and Waikavirus, tentatively named Persimmon ampelovirus (PAmpV), Persimmon polerovirus (PPolV), and Persimmon waikavirus (PWaiV). The alignment of two PAmpV variants with Plum bark necrosis stem pitting–associated virus isolates had 72.5%–79.0% amino acid sequence identities with RNA-dependent RNA polymerase, 71.6%–79.2% with a heat shock protein 70 homolog, and 66.2%–69.8% with coat protein, respectively. Two PPolV variants showed the highest amino acid sequence identities (46.6%) with the P1–P2 fusion protein of Brassica yellows virus. PWaiV had the highest amino acid sequence identity (41.9%) with the conserved domain between proteinase and polymerase of Rice tungro spherical virus. Reverse-transcription and polymerase chain reaction detected Persimmon virus A, Apple crinkle fruit viroid, and Citrus viroid VI from the mother clone with good growth, and PAmpV, PPolV, and Persimmon latent viroid (PLVd) additionally from 20 trees with poor growth. PAmpV, PPolV, and PLVd were detected from four, 10, and 10 of 14 trees with good growth, respectively, and the grafting of budwood harboring these three pathogens caused significant stunt in mother clones. [ABSTRACT FROM AUTHOR]

Japanese apricot (Prunus mume Sieb. et Zucc.) is one of the most popular fruit tree species in Japan and is most densely cultivated in Wakayama Prefecture. Since the 1980s, graft-transmissible symptoms, such as leaf-edge necrosis and incomplete flower development, have been observed in Nanko, the major Japanese apricot cultivar in Wakayama. Two ampeloviruses, plum bark necrosis stem pitting-associated virus (PBNSPaV) and little cherry virus 2 (LChV-2) were detected in Nanko trees showing typical symptoms. However, there is currently insufficient epidemiological data to infer that these viruses cause the symptoms. In this study, we conducted a large-scale survey of symptoms and RT-PCR detection of the two viruses in midwestern districts, the major cultivation areas in Wakayama. Among 208 surveyed Nanko trees, two viral infections were significantly associated with incomplete flower development, low fruit bearing rate, and interveinal chlorosis. LChV-2 infection also affected Nanko fruit and stone sizes. Additionally, we showed that the two viruses were already widely distributed throughout the main cultivation area. These results imply that the two ampeloviruses cause overall yield loss in Japanese apricot in Wakayama Prefecture. [ABSTRACT FROM AUTHOR]

Air potato (Dioscorea bulbifera) plants being grown at the Florida Department of Agriculture and Consumer Services Division of Plant Industry Biological Control Laboratory II in Alachua County, Florida were observed exhibiting foliar mosaic symptoms characteristic of virus infection. A double-stranded RNA library generated from a symptomatic plant underwent high-throughput sequencing to determine if viral pathogens were present. Sequence data revealed the presence of two viral genomes, one with properties congruent with members of the genus Potyvirus (family Potyviridae), and the other with members of the genus Ampelovirus (family Closteroviridae). Sequence comparisons and phylogenetic placement indicate that both viruses represent novel species. The names "dioscorea mosaic virus" and "air potato virus 1" are proposed for the potyvirus and ampelovirus, respectively. [ABSTRACT FROM AUTHOR]

The seasonal acquisition pattern of Grapevine leafrollassociated virus 1 (GLRaV-1) and Grapevine leafroll-associated virus 3 (GLRaV-3) by the grape mealybug, Pseudococcus maritimus (Erhorn), was determined over two consecutive years in a leafroll-diseased vineyard in the Finger Lakes region of New York. Groups of 1-15 immature mealybugs (1st, 2nd or 3rd instars), adults or eggs were collected from April to November on 20 selected vines infected with GLRaV-1 and/or GLRaV-3. Results of RT-PCR using specific primers were consistent with a preferential virus acquisition by overwintered, 1st instar nymphs in April and May (87%, 45 of 52) followed by summer generation immature mealybugs in July (82%, 28 of 34). Crawlers collected on or near ovisacs in September (100%, 12 of 12) were aviruliferous and eggs collected in June (100%, 250 of 250) as well as crawlers hatching from eggs (100%, 51 of 51) tested negative for the two target viruses in RT-PCR. Importantly, crawlers collected in the vineyard at bud swell in April transmitted GLRaV-1 to healthy grapevines in a greenhouse. These findings suggest that disease management strategies designed to mitigate leafroll spread by reducing vector populations should target overwintered crawlers and second instar crawlers at a very early grapevine development stage, i.e. from bud swell to bloom, as well as the summer generation crawlers later in mid-summer. [ABSTRACT FROM AUTHOR]

Grapevine leafroll-associated virus 3 (GLRaV-3) is widely spread in China. Here we report, for the first time, the complete nucleotide sequence of the Chinese isolate (LN) of GLRaV-3. The 18,563-nt genomic RNA is the largest of the GLRaV-3 genomes reported to date, with a 5′ untranslated region of 802 nt. Its sequence shares 87.99-98.15 % identity with those of previously reported isolates, and phylogenetic analysis suggested placing isolate LN in group 3, together with another fully sequenced isolate, PL-20. [ABSTRACT FROM AUTHOR]

Spread patterns of a Grapevine leafroll-associated virus 1 (GLRaV-1) epidemic and a mealybug infestation survey over 10 year were recorded in two Burgundy French vineyards to investigate the relation between them. The temporal evolution of leafroll spread at both study sites was compared on disease incidence data with logistic regression models. We first tested if the spatial distribution of the disease and the mealybug were aggregated using permutation methods, then we tested the independence between the two spatial patterns by randomly shifting one pattern. In Bonzon, an increase from 5 % to 86 % of leafroll prevalence was observed over an 8-year time span, whereas leafroll prevalence remained stable around 5 % in Marsannay-la-Côte during the same period. In Bonzon, the disease spread rapidly from older neighbouring vineyards in four main patches while no spread of the disease was recorded from infected vines in Marsannay-la-Côte. The mealybug Phenacoccus aceris was recorded on 74 % of vines in Bonzon throughout the study and only 6 % of vines in Marsannay-la-Côte. In the latter location, the disease was not associated with the presence of the mealybug, so that it may have arisen from infected plant material escaping the sanitary inspection. In Bonzon, the significant statistical correlation between the mealybug distribution and diseased plants suggests that P. aceris was responsible for the rapid spread of GLRaV-1 in the vineyard. This is the first report of GLRaV-1 natural spread in Europe. [ABSTRACT FROM AUTHOR]

GLRaV-3, a member of the Closteroviridae family and type member of the genus Ampelovirus, is involved in the grapevine leafroll disease. Until now no RNA silencing suppressor has been found among viruses of this genus, contrary to what happens with a large number of other viral genera. In the sister genus Closterovirus, RNA silencing suppressors are present in the 3' end of the genome and have molecular weights close to 20 KDa. To test for RNA suppressing activity screening of p21, p19.6 and p19.7 proteins, coded for in an analogous genomic location of the GLRaV-3 was undertaken. Only p19.7 revealed suppressor activity demonstrated in diverse silencing inducing systems. This suppressor is able to overcome strong silencing inducers and shares several properties with the BYV p21-like family of suppressors of the closteroviruses. This is the first report of an RNA silencing suppressor in the genus Ampelovirus. [ABSTRACT FROM AUTHOR]

The attention was paid to the detection of pistachio ampelovirus A (PAVA) of the family I Closteroviridae i that was recently reported in pistachio in the USA (Al Rwahnih et al. [1]). Keywords: Pistachio; Ampelovirus; Germplasm EN Pistachio Ampelovirus Germplasm 1335 1335 1 11/29/21 20211101 NES 211101 Pistachio ( I Pistacia vera i L.) is an important crop in Tunisia. [Extracted from the article]