Background

Citrus industry is worldwide dramatically affected by outbreaks of Citrus tristeza virus (CTV). Controls should be applied to nurseries, which could act as diversity hotspots for CTV. Early detection and characterization of dangerous or emerging strains of this virus greatly help to prevent outbreaks of disease. This is particularly relevant in those growing regions where no dedicated certification programs are currently in use.

Citrus vein enation virus (CVEV) was described in Spain and then it has been reported in several citrus growing areas of Asia, America and Australia. Here, the occurrence of CVEV in Italy has been documented for the first time. The full genome sequence of a CVEV Italian isolate (14Q) was determined by high-throughput sequencing and the presence of the virus was confirmed by RT-PCR and graft-transmission to indicator plants, from which the virus was recovered six-months post-inoculation. 

Citrus concave gum-associated virus (CCGaV) is a negative-stranded RNA virus, first reported a few years ago in citrus trees from Italy. It has been reported in apple trees in the USA and in Brazil, suggesting a wider host range and geographic distribution. Here, an anti-CCGaV polyclonal antiserum to specifically detect the virus has been developed and used in a standard double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) that has been validated as a sensitive and reliable method to detect this virus both in citrus and apple trees. In contrast, when the same antiserum was used in direct tissue-blot immunoassay, CCGaV was efficiently detected in citrus but not in apple.

Watermelon crinkle leaf-associated virus 1 and watermelon crinkle leaf-associated virus 2 (WCLaV-1 and WCLaV-2), two unclassified members of the order Bunyavirales, are phylogenetically related to members of the genus Coguvirus (family Phenuiviridae). The genome of both viruses was reported previously to be composed of three RNA segments. 

Pomegranate is an important crop in the Mediterranean Basin that can be affected by a range of pathogens. With the aim to better understand the impact of viral diseases on pomegranate, two leaf samples from Turkey showing virus-like symptoms such as chlorotic spots and oak-leaf patterns were subjected to high throughput sequencing (HTS).

The use of high throughput sequencing (HTS) for the analysis of Spanish olive trees showing leaf yellowing discoloration, defoliation, and/or decline has provided new insights into the olive viruses present in Spain and has opened discussions about the pros and cons of these technologies for diagnostic purposes

Loquat (Eriobotrya japonica) is an important crop in Spain. To date, only one viral species, apple stem pitting virus (ASPV), has been detected in Spanish loquat orchards. 

Grapevine virus H (GVH) is a member of the genus Vitivirus in the family Betaflexiviridae (subfamily Trivirinae, order Tymovirales) that infects grapevine (Candresse et al., 2018). GVH was first identified in a symptomless grapevine of an unknown cultivar from Portugal in 2018 (Candresse et al. 2018), and since then the virus has been reported only from California (Diaz‑Lara et al. 2019).

Several vitiviruses have been detected in Greek vineyards (Avgelis and Roubos 2000; Dovas and Katis 2003a; 2003b; Panailidou et al. 2019; Lotos et al. 2020), but no information was available on the presence of GVH.

Grapevine (Vitis vinifera) is one of the most ancient crops cultivated worldwide for the production of both fresh grapes and wine, which represents an important source of income for many countries. Europe is the leading global wine producer, with about 50% of the world’s vine-growing area, with 3.3 million ha (Food and Agriculture Organization of the United Nations Statistics Division, FAOSTAT, 2018). Grapevine can be affected by virus and virus-like diseases that may significantly reduce the productive life of the plants as well as the grape production in terms of the quantity and quality of the berries [1]. In fact, the grapevine has been described as the crop that hosts the largest number of plant viruses, with more than 85 viral species known to infect this important crop to date [2,3].

Grapevine (Vitis vinifera) is one of the most ancient crops cultivated worldwide for the production of both fresh grapes and wine, which represents an important source of income for many countries. Europe is the leading global wine producer, with about 50% of the world’s vine-growing area, with 3.3 million ha (Food and Agriculture Organization of the United Nations Statistics Division, FAOSTAT, 2018). Grapevine can be affected by virus and virus-like diseases that may significantly reduce the productive life of the plants as well as the grape production in terms of the quantity and quality of the berries [1]. In fact, the grapevine has been described as the crop that hosts the largest number of plant viruses, with more than 85 viral species known to infect this important crop to date [2,3].