We studied the resistance to tomato spotted wilt virus in plant introduction accession (PI)-151225 and PI-159236 under Mediterranean climatic conditions. Two temperature regimes were utilized, corresponding to early and late cultivation cycles. Inoculations were made at 2- and 4-leaf stages to determine the effect of early infection. The existence of interaction between temperature regime and developmental stage was also studied. When plants of both PIs were maintained at 30/18°C (day/night), all plants at both growth stages when inoculated developed systemic infection. At 25/18°C, only those plants inoculated at 2-leaf stage became systematically infected; however, those inoculated at the 4-leaf stage behaved as resistant. Thus, there was an interaction between temperature regime and growth stage. There is potential for using this type of resistance in areas with mild climates, providing seedling infections are avoided.

Pepino mosaic virus (PepMV), a potexvirus first described in 1980 from pepino (Solanum muricatum) plants cultivated in Peru, was isolated from diseased tomato plants in the Netherlands in 1999, and is now the cause of an emerging tomato disease in Europe. In a survey of central and southern Peru, 65 wild and four cultivated populations of Lycopersicon, as well as six populations of other species of Solanaceae, were tested for the presence of PepMV and six other viruses. Of the Lycopersicon population sampled, 23 (35.4%) reacted positively in double antibody sandwich (DAS)‐enzyme‐linked immunosorbent assay (ELISA) with antisera to PepMV. DAS‐ELISA tests for PepMV of other solanaceous species were negative, except for one sample of pepino (Solanum muricatum). Mechanical inoculation of susceptible Lycopersicon esculentum cv. NE‐1 plants with crude sap extracts of 20 of these samples confirmed that 15 of them (from the Departments of Apurimac, Arequipa and Moquegua) were infected with PepMV; these inoculated plants were also DAS‐ELISA positive and, in most cases, developed symptoms. Thirteen of the infective extracts were obtained from plants of wild Lycopersicon species (three L. chilense, three L. chmielewskii, two L. parviflorum and five L. peruvianum) and one each from the cultivated species L. esculentum and S. muricatum. The wild Lycopersicon species are newly reported natural hosts of PepMV. Tests for the other six viruses were negative, except that two samples contained Tomato mosaic virus. Thus, PepMV occurs in Lycopersicon species in central and southern Peru, even in isolated wild populations. These results indicate that the virus is not new to the region and has an efficient mechanism of natural transmission.

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The high variability lbund among Tomato yellow leaf curl virus (TYLCV) isolates from different geographical areas makes progress in breeding for TYLCV resistance slow.By using Agrobacterium-mediated inoculation, we have identified several new resistant sources to TYLCV within a extraordinarily variable wild Lycopersicon gene pool, collected in semidesert areas of Ecuador and Peru changed into wet by "El Ni6o". This screening assay revealed a high susceptibility within L. esculentum and L. pennellii, but different levels of resistance within L. pitpwinellifolium and L. hirsutum. Resistance level was related to the collection place, being concentrated in accessions collected in Northern Peru (Piura province).Agroinoculation allowed the selection of 4 Lycopersicon pimpinellifoliuni and 2 Lycopersicon hirsutum accessions with higher level of resistance than accessions of these species previously reported, avoiding interference due to vector resistance mechanisms reported in both species.These new resistance sources will be included in pyramiding strategies aimed at obtaining durable resistance to TYLCV.

A novel haplotype-based approach that uses Procrustes analysis and automatic classification was used to provide further insights into tomato history and domestication. Agrarian societies domesticated species of interest by introducing complex genetic modifications. For tomatoes, two species, one of which had two botanical varieties, are thought to be involved in its domestication: the fully wild Solanum pimpinellifolium (SP), the wild and semi-domesticated Solanum lycopersicum var. cerasiforme (SLC) and the cultivated S. l. var. lycopersicum (SLL). The Procrustes approach showed that SP evolved into SLC during a gradual migration from the Peruvian deserts to the Mexican rainforests and that Peruvian and Ecuadorian SLC populations were the result of more recent hybridizations. Our model was supported by independent evidence, including ecological data from the accession collection site and morphological data. Furthermore, we showed that photosynthesis-, and flowering time-related genes were selected during the latitudinal migrations.