Viruses affecting lentil (Lens culinaris Medik.) in Greece; incidence and genetic variability of Bean leafroll virus and Pea enation mosaic virus

In Greece, lentil (Lens culinaris Medik.) crops are mainly established with non-certified seeds of local landraces, implying high risks for seed transmitted diseases. During April and May of the 2007–2012 growing seasons, surveys were conducted in eight regions of Greece (Attiki, Evros, Fthiotida, Korinthos, Kozani, Larissa, Lefkada and Viotia) to monitor virus incidence in lentil fields. A total of 1216 lentil samples, from plants exhibiting symptoms suggestive of virus infection, were analyzed from 2007 to 2009, using tissue-blot immunoassays (TBIA). Pea seed-borne mosaic virus (PSbMV) overall incidence was 4.9%, followed by Alfalfa mosaic virus (AMV) (2.4%) and Bean yellow mosaic virus (BYMV) (1.0%). When 274 of the samples were tested for the presence of luteoviruses, 38.8% were infected with Bean leafroll virus (BLRV). Since BLRV was not identified in the majority of the samples collected from 2007 to 2009, representative symptomatic plants (360 samples) were collected in further surveys performed from 2010 to 2012 and tested by ELISA. Two viruses prevailed in those samples: BLRV (36.1%) was associated with stunting, yellowing, and reddening symptoms and Pea enation mosaic virus-1 (PEMV-1) (35.0%) was associated with mosaic and mottling symptoms. PSbMV (2.2%), AMV (2.2%), BYMV (3.9%) and CMV (2.8%) were also detected. When the molecular variability was analyzed for representative isolates, collected from the main Greek lentil production areas, five BLRV isolates showed 95% identity for the coat protein (CP) gene and 99% for the 3’ end region. Three Greek PEMV isolates co-clustered with an isolate from Germany when their CP sequence was compared with isolates with no mutation in the aphid transmission gene. Overall, limited genetic variability was detected among Greek isolates of BLRV and PEMV

The westward journey of alfalfa leaf curl virus

Alfalfa leaf curl virus (ALCV), which causes severe disease symptoms in alfalfa (Medicago sativa L.) and is transmitted by the widespread aphid species, Aphis craccivora Koch, has been found throughout the Mediterranean basin as well as in Iran and Argentina. Here we reconstruct the evolutionary history of ALCV and attempt to determine whether the recent discovery and widespread detection of ALCV is attributable either to past diagnostic biases or to the emergence and global spread of the virus over the past few years. One hundred and twenty ALCV complete genome sequences recovered from ten countries were analyzed and four ALCV genotypes (ALCV-A, ALCV-B, ALCV-C, and ALCV-D) were clearly distinguished. We further confirm that ALCV isolates are highly recombinogenic and that recombination has been a major determinant in the origins of the various genotypes. Collectively, the sequence data support the hypothesis that, of all the analyzed locations, ALCV likely emerged and diversified in the Middle East before spreading to the western Mediterranean basin and Argentina

An Annotated List of Legume-Infecting Viruses in the Light of Metagenomics

Legumes, one of the most important sources of human food and animal feed, are known to be susceptible to a plethora of plant viruses. Many of these viruses cause diseases which severely impact legume production worldwide. The causal agents of some important virus-like diseases remain unknown. In recent years, high-throughput sequencing technologies have enabled us to identify many new viruses in various crops, including legumes. This review aims to present an updated list of legume-infecting viruses. Until 2020, a total of 168 plant viruses belonging to 39 genera and 16 families, officially recognized by the International Committee on Taxonomy of Viruses (ICTV), were reported to naturally infect common bean, cowpea, chickpea, faba-bean, groundnut, lentil, peas, alfalfa, clovers, and/or annual medics. Several novel legume viruses are still pending approval by ICTV. The epidemiology of many of the legume viruses are of specific interest due to their seed-transmission and their dynamic spread by insect-vectors. In this review, major aspects of legume virus epidemiology and integrated control approaches are also summarized

Virus Surveys in Olive Orchards in Greece Identify Olive Virus T, a Novel Member of the Genus Tepovirus

Field surveys were conducted in Greek olive orchards from 2017 to 2020 to collect information on the sanitary status of the trees. Using a high-throughput sequencing approach, viral sequences were identified in total RNA extracts from several trees and assembled to reconstruct the complete genomes of two isolates of a new viral species of the genus Tepovirus (Betaflexiviridae), for which the name olive virus T (OlVT) is proposed. A reverse transcription–polymerase chain reaction assay was developed which detected OlVT in samples collected in olive growing regions in Central and Northern Greece, showing a virus prevalence of 4.4% in the olive trees screened. Sequences of amplified fragments from the movement–coat protein region of OlVT isolates varied from 75.64% to 99.35%. Three olive varieties (Koroneiki, Arbequina and Frantoio) were infected with OlVT via grafting to confirm a graft-transmissible agent, but virus infections remained latent. In addition, cucumber mosaic virus, olive leaf yellowing-associated virus and cherry leaf roll virus were identified