Current status of cucurbit viruses in Venezuela and characterization of Venezuelan isolates of Zucchini yellow mosaic virus

Abstract

In Venezuela, cucurbit viruses have been associated with important yield losses. Therefore, an extensive survey was conducted to determine the major cucurbit viruses in this country. Leaf samples from 284 cucurbit plants exhibiting virus-like symptoms were collected mainly in 2009-2010 from several states of Venezuela. They were assessed for viral infection by polymerase chain reaction (PCR) for Melon chlorotic mosaic virus (MeCMV) and reverse transcriptase (RT)-PCR for Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV) and Cucurbit aphid-borne yellows virus (CAB-YV). The most common virus in cucurbit fields, MeCMV, was present in 65Á8% of samples. Its associated alphasatellite was found in 78% of samples positive for MeCMV. PRSV, ZYMV and WMV were found with different prevalence: 34Á2, 32Á4 and 1Á1% respectively. CMV was also detected (6Á7%) but SqMV and CABYV were not found. Single infections were more frequent than mixed infections (56Á4 and 38Á6%, respectively). For ZYMV, comparison and phylogenetic analyses of either polymerase and coat protein (NIb-CP) partial sequences or CP complete sequences revealed a low genetic diversity within Venezuelan isolates. Thirty-four ZYMV isolates were used for serological and biological analysis. Thirteen monoclonal antibodies showed a major group of isolates spread in several states and two groups located in Zulia only. Venezuelan ZYMV isolates showed biological variability on cucurbit cultivars susceptible, tolerant or resistant to ZYMV. Resistance to ZYMV in cucumber appears potentially durable, whereas resistance or tolerance in zucchini and melon may be easily overcome.

Melon chlorotic mosaic virus and associated alphasatellite from Venezuela: genetic variation and sap transmission of a begomovirus–satellite complex

“…Field surveys revealed that 146 out of 187 (78%) positive samples for MeCMV were also positive for MeCMA, indicating a high frequency of this virus–satellite complex (Romay et al ., ). In the Venezuelan states Falcón, Guárico, Lara and Zulia, the frequency of the MeCMV–MeCMA complex was 73, 63, 64 and 83%, respectively (authors' unpublished data).…”

“…Thus, it can be speculated that MeCMV has also emerged from weeds as a consequence of introduction of the B biotype of B. tabaci that is now widespread in the country (Romay et al ., ). Although MeCMV has only been found naturally infecting cucurbits, either cultivated or wild (Romay et al ., ), surveys will be required to identify potential non‐cucurbit reservoirs.…”

“…These five cucurbit begomoviruses are phylogenetically related and belong to the SLCV clade (Romay et al, 2010;Brown et al, 2011). In Venezuela, MeCMV was first detected infecting melon (Cucumis melo) in Lara state (Ram ırez et al, 2004) and it is currently found infecting watermelon (Citrullus lanatus), squash (Cucurbita moshata), cucumber (Cucumis sativus) and some wild cucurbits across the country (Romay et al, 2010(Romay et al, , 2014.…”

“…In Venezuela, MeCMV is the major constraint for melon and watermelon production and yield losses caused by this virus are estimated to exceed 80% (Romay et al, 2014). However, molecular and biological features of this begomovirus and associated alphasatellite remain unclear.…”

Molecular variability of Merremia mosaic virus infecting tomatoes in Venezuela

“…In Venezuela, severe begomoviral outbreaks have been reported in tomatoes and other crops Romay et al 2010Romay et al , 2014. Recently, Merremia mosaic virus (MeMV) was found as one of the three more prevalent begomoviruses in Venezuelan tomato fields (Geraud-Pouey et al 2015).…”