Viruses Infecting Tomato in València, Spain: Occurrence, Distribution and Effect of Seed Origin

Abstract

Viral diseases are a serious limitation to the tomato crop in the region of Vale`ncia, Spain. A survey of tomato viruses in open field cultivation plots was made in the three provinces of this region. A total of 228 plots classified according to the origin of the seed (farmer seed plots or commercial seed plots) were surveyed, from which 1300 individual plants were sampled and tested for Cucumber mosaic virus (CMV), Pepino mosaic virus (PepMV), Parietaria mottle virus (PMoV), Potato virus Y (PVY), Tomato mosaic virus (ToMV), Tomato spotted wilt virus (TSWV) and for the tomato yellow leaf curl disease (TYLCD). Virus infection was detected in 58.9% of the plants sampled and in 86.0% of the plots surveyed. All these viruses were detected, and the most prevalent were ToMV and PVY (34.1% and 27.1% of infected plants, respectively), but PMoV and TYLCD were the less prevalent (1.2% and 1.3% of infected plants, respectively). Differences among provinces and seed origin were found for most of the viruses studied. In particular, both ToMV and PVY had a higher level of infection in plants from farmer seed plots than in commercial seed plots, which accounts for the higher percentage of virus-infected plants in the former (64.2%) when compared to the latter (49.1%). Single and multiple infections were found in 42.38% and 16.54% of the samples, respectively. The most common multiple infection was of ToMV, PVY or both. These results show that the percentage of infected plants and plots in open field cultivation is very high in this region and the origin of the seed is an important factor in the incidence of virus infection. In this respect, preventive measures, including virus-free seed, resistant cultivars and improved cultural practices, could reduce the incidence of virus infection.

The Influence of Crop Habitat and Control Strategies on Pepper Viruses in Andalusia (Spain)

“…Similar results were obtained for field-grown pepper in Turkey with PVY and TMV in double infections [24], or with PVY and ToMV in Ethiopia [25], with PVY and CMV in Serbia [26], and in tomatoes in Valencia (Spain) where PVY and ToMV were the predominant viruses [5]. The inland climatic conditions of the Andalusian regions where these field pepper crops were located did not favor the presence of F. occidentalis thrips and the transmission of TSWV.…”

“…Populations of viruses carried in seed or transmitted by vectors to field tomato crops can determine levels of infection of greenhouse-grown tomato during a consecutive season [5]. In particular, arthropods cross boundaries between different habitats [29], and this could affect the transmission of viruses as they may be vectors, and influence the response of their predators and parasitoids.…”

“…An element determining the success of control can be the existence of arthropod pest and disease reservoirs surrounding the greenhouses, associated with wild vegetation, or with open-field cultivated crops [4]. This also holds for plant viruses, and examples exist where the incidence in outdoor crops during seasonal periods is believed to affect that in nearby greenhouses during off-season production such as in Mediterranean horticultural production where summer open-field and greenhouse winter crops often overlap [5].…”

Resistance to Tospoviruses in Vegetable Crops: Epidemiological and Molecular Aspects

“…As in the case of Sw-5b, Tsw RB variants of TSWV have been identified (74,81,104,111). The resistance conferred by Tsw is observed to exhibit a reduced performance at prolonged higher temperatures and a lower efficiency when plants are infected during an early growth stage (82,103,104,122). Although RB by TSWV occurs at increasing frequencies (74,82,(103)(104)(105), in some pepper cultivation areas, such as South and Central America, two closely related tospoviruses, TCSV and GRSV, are emerging and seem to be expanding their geographic range and economic impact to Central and North America.…”

Symptoms and Host Range

“…(reviewed by Syller, 2012) Many crop plants, especially those that are vegetatively propagated but also annual plants, are coinfected by more than one virus (Aritua et al, 2007;Soler et al, 2010). Satellite RNA, Defective RNA, and Defective Interfering RNA Satellite viruses and RNAs and defective and defective interfering RNA depend on their helper virus for their replication (see Chapter 5, Section II).…”