Mirabilis jalapa mottle virus: a new carlavirus infecting four o'clocks

Two Novel Betarhabdovirins Infecting Ornamental Plants and the Peculiar Intracellular Behavior of the Cytorhabdovirus in the Liana Aristolochia gibertii

Two novel members of the subfamily Betarhabdovirinae, family Rhabdoviridae, were identified in Brazil. Overall, their genomes have the typical organization 3'-N-P-P3-M-G-L-5' observed in mono-segmented plant-infecting rhabdoviruses. In aristolochia-associated cytorhabdovirus (AaCV), found in the liana aristolochia (Aristolochia gibertii Hook), an additional short orphan ORF encoding a transmembrane helix was detected between P3 and M. The AaCV genome and inferred encoded proteins share the highest identity values, consistently < 60%, with their counterparts of the yerba mate chlorosis-associated virus (Cytorhabdovirus flaviyerbamate). The second virus, false jalap virus (FaJV), was detected in the herbaceous plant false jalap (Mirabilis jalapa L.) and represents together with tomato betanucleorhabdovirus 2, originally found in tomato plants in Slovenia, a tentative new species of the genus Betanucleorhabdovirus. FaJV particles accumulate in the perinuclear space, and electron-lucent viroplasms were observed in the nuclei of the infected cells. Notably, distinct from typical rhabdoviruses, most virions of AaCV were observed to be non-enclosed within membrane-bounded cavities. Instead, they were frequently seen in close association with surfaces of mitochondria or peroxisomes. Unlike FaJV, AaCV was successfully graft-transmitted to healthy plants of three species of the genus Aristolochia, while mechanical and seed transmission proved unsuccessful for both viruses. Data suggest that these viruses belong to two new tentative species within the subfamily Betarhabdovirinae.

Molecular characterization of a new begomovirus infecting Mirabilis jalapa in northern India

Begomoviruses are whitefly-transmitted single-stranded DNA viruses that are responsible for considerable economic losses. A begomovirus, alphasatellite and betasatellite were characterized in a Mirabilis jalapa plant exhibiting severe leaf curling and mottling symptoms. The complete viral genome shared highest sequence identity of 87% with pedilanthus leaf curl virus (AM712436), reported from Pakistan. Additionally, the viral genome was 84% identical to that of chilli leaf curl India virus (KX951415) and 83% identical to that of tobacco curly shoot virus (GU1999584), which were previously reported to infect M. jalapa in India and China, respectively. Based on the ICTV criterion for begomovirus species demarcation (≥91% sequence identity for the complete genome), the virus represents a new species, for which we propose the name Mirabilis leaf curl virus. The alphasatellite and betasatellite sequences were similar to the corresponding sequences of ageratum yellow vein India alphasatellite (KU852743; 99% identity) and tomato leaf curl Patna betasatellite (HQ180394; 86% identity) sequences, respectively. This report describes a new begomovirus-satellite disease complex in M. jalapa.

Characterization of New Isolates of Apricot vein clearing-associated virus and of a New Prunus-Infecting Virus: Evidence for Recombination as a Driving Force in Betaflexiviridae Evolution

Double stranded RNAs from Prunus samples gathered from various surveys were analyzed by a deep-sequencing approach. Contig annotations revealed the presence of a potential new viral species in an Azerbaijani almond tree (Prunus amygdalus) and its genome sequence was completed. Its genomic organization is similar to that of the recently described Apricot vein clearing associated virus (AVCaV) for which two new isolates were also characterized, in a similar fashion, from two Japanese plums (Prunus salicina) from a French germplasm collection. The amino acid identity values between the four proteins encoded by the genome of the new virus have identity levels with those of AVCaV which fall clearly outside the species demarcation criteria. The new virus should therefore be considered as a new species for which the name of Caucasus prunus virus (CPrV) has been proposed. Phylogenetic relationships and nucleotide comparisons suggested that together with AVCaV, CPrV could define a new genus (proposed name: Prunevirus) in the family Betaflexiviridae. A molecular test targeting both members of the new genus was developed, allowing the detection of additional AVCaV isolates, and therefore extending the known geographical distribution and the host range of AVCaV. Moreover, the phylogenetic trees reconstructed with the amino acid sequences of replicase, movement and coat proteins of representative Betaflexiviridae members suggest that Citrus leaf blotch virus (CLBV, type member of the genus Citrivirus) may have evolved from a recombination event involving a Prunevirus, further highlighting the importance of recombination as a driving force in Betaflexiviridae evolution. The sequences reported in the present manuscript have been deposited in the GenBank database under accession numbers KM507061-KM504070.

Genetic variability of blueberry scorch virus isolates from highbush blueberry in New York State

The genetic variability of blueberry scorch virus (BlScV) isolates from New York was determined within a portion of the RNA-dependent RNA polymerase gene and the triple gene block and coat protein (CP) genes. Phylogenetic analysis of 19 New York isolates and other isolates for which sequence information is available in GenBank revealed two distinct clades, regardless of the coding region analyzed, and limited variability within (0.029 ± 0.007) and between (0.183 ± 0.032) phylogroups. Recombination events were identified in the CP gene of three New York isolates, and codons of the five BlScV genes characterized were found to be under neutral or negative selective pressure.