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

Abstract

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.

Development of a Real-Time Loop-Mediated Isothermal Amplification Assay for the Rapid Detection of Olea Europaea Geminivirus

“…Some of them are reported to be transmitted by different vectors [ 9 , 27 , 28 , 29 ], but the use of infected propagating material might represent the major, though not the only, means of virus spread [ 29 , 30 , 31 , 32 , 33 ]. The first report on a probable viral disease of olive goes back to 1938 [ 34 ] and, since then, several virus-like diseases and viruses have been reported over the years in different areas where olive cultivation plays a prominent role [ 14 , 35 , 36 , 37 , 38 , 39 , 40 ]. Some of these are agents of recognized diseases, others cause latent infections with still undetermined effects on the host [ 29 ].…”

“…Indeed, in the last decade, olive production has suffered an enormous decline due to the emergence of biotic agents that have significantly undermined the Mediterranean economy related to olive and the olive oil industry; a dramatic example being the Xylella fastidiosa epidemic in 2013, which decimated olive trees in Apulia [ 11 ] and created huge losses for the local olive economy and oil production outputs, posing critical challenges for its management, as well as dramatic changes in the landscape [ 12 , 13 ]. Furthermore, the vegetative propagation of olive trees using cuttings of semi-wood has contributed over the years to the spread of systemic-pathogens, particularly viruses [ 14 ]. Nevertheless, despite the difficulty of associating specific symptoms to a particular virus, many viruses are easily transmitted through infected propagation material [ 15 ], and many olive infecting viruses are symptomless.…”

Identification and complete genome sequencing of a divergent olive virus T isolate and an olive leaf yellowing-associated virus isolate naturally infecting olive trees in Greece

“…Nevertheless, due to its vegetative propagation through cuttings, it has accumulated several pathogens, including viruses. More than seventeen viruses belonging to different genera or families have been reported to naturally infect olive trees [1][2][3][4][5][6]. Over the last decade, the wide application of high-throughput sequencing (HTS) has allowed the rapid identification and characterization of several novel or new strains of known viruses in various plant species using different technologies [7][8][9][10].…”

“…Over the last decade, the wide application of high-throughput sequencing (HTS) has allowed the rapid identification and characterization of several novel or new strains of known viruses in various plant species using different technologies [7][8][9][10]. Hence, in olive, new viral agents have also come up or divergent variants of known viral agents have been molecularly characterized with the application of HTS [5,6,11,12].…”

A Bipartite Geminivirus with a Highly Divergent Genomic Organization Identified in Olive Trees May Represent a Novel Evolutionary Direction in the Family Geminiviridae

“…Olive ( Olea europaea L.) is one of the most cultivated fruit crops around the world and has significant environmental, social and landscape impact in many countries such as Portugal. Olive trees are known to be infected by 17 different viruses [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. A common feature of olive viruses is the difficulty of associating viral presence to symptoms.…”