Survey on Pepino mosaic potexvirus on wild and cultivated Lycopersicon in Peru
In March 2000, a survey on Pepino mosaic potexvirus (EPPO Alert List) was carried out in central and southern Peru (Departments of Lima, Ayacucho, Apurimac, Arequipa, Moquegua and Tacna). These areas are part of the ‘Sierra’ (Andean highlands, mild climate) and ‘Costa’ (coastal region, arid and warm). 65 populations of wild Lycopersicon (L. peruvianum, L. parviflorum, L. chilense, L. chmiekewskii, L. pimpinellifolium), and four cultivated tomato (L. esculentum) fields were sampled and tested by DAS-ELISA for 5 viruses (Pepino mosaic potexvirus, Potato X potexvirus, Potato Y potyvirus, Tobacco mosaic tobamovirus and Tomato mosaic tobamovirus). In addition, six samples of other Solanaceae (Datura, Nicotiana, Solanum caripense, S. muricatum) were also collected. Pepino mosaic potexvirus was detected in 24 samples and Tomato mosaic tobamovirus was found in 2 samples. Mechanical inoculation of susceptible L. esculentum (cv. NE-1) with crude sap extracts of 20 samples confirmed that 15 of them were infected by Pepino mosaic potexvirus (DAS-ELISA positive and, in most cases, development of symptoms). These infected samples had been collected from the Departments of Apurimac, Arequipa and Moquegua and were obtained from wild Lycopersicon (3 samples of L. chilense, 3 L. chmielewskii, 2 L. parviflorum and 5 L peruvianum), from crops of tomato (1 sample) and S. muricatum (1 sample). These results showed that in Peru, L. chilense, L. chmielewskii, L. parviflorum and L peruvianum are natural hosts of the virus, as well as cultivated L. esculentum and S. muricatum. The fact that the virus is found in wild plants, and in many cases in isolated populations, indicate that factors other than mechanical transmission, are involved in virus spread. For example, in southern Spain, growers have observed that in glasshouses where bumble-bees were used to improve pollination, virus spread seemed faster. In inoculation tests on L esculentum cv. NE-1, symptoms caused by Peruvian isolates were milder than those of a European isolate. In most cases, a mild, faint, light green to dark green mosaic in young leaves, and production of nettle-like leaves were observed. It was recalled that genetic differences between European and Peruvian isolates had already been found in other studies.
Sources
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Soler, S.; Prohens, J.; Díez, M.J.; Nuez, F. (2002) Natural occurrence of Pepino mosaic virus in Lycopersicon species in Central and Southern Peru.
Journal of Phytopathology, 150(2), 49-53.
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