Samples of tomato (Lycopersicon esculentum Mill) ‘Alambra’ were collected in commercial fields of Elias Fausto, Monte-Mor and Mogi-Guaçu, SP. The plants with virus-like symptoms, especially yellow mosaic were submitted, to biological and serological identification tests. For biological tests, the host range was determined by indicator and differential plants in the family Chenopodiaceae and Solanaceae. The serological identification was made by PTA-ELISA with polyclonal antiserum against Tospovirus, Tobamovirus, Potyvirus and Cucumovirus and by DAS-ELISA, by using monoclonal antibodies against PVY common strain (PVYº), PVY chlorotic strain (PVY C) and PVY necrotic strain (PVY N). All the tested samples showed positive reaction in PTA-ELISA with antiserum against PVY and negative reaction with the antiserum against the remaining viruses. In DAS-ELISA, positive reaction occurred with PVY common strain. Among the host plants, Chenopodium amaranticolor reacted with local lesions, while N. glutinosa and N. tabacum ‘WB’ showed systemic mosaic and the ‘Alambra’ reacted with yellow mosaic, while Datura stramonium, D. metel and C. annuum ‘Magda’ were not infected. The reaction on the differential host C. annuum ‘Magda’ permitted to identify the PVY pathotype 1 in all the 19 samples. To evaluate the reaction of the 19 accesses of Lycopersicon spp. from the IAC active bank of germoplasm, one of the samples of tomato ‘Alambra’ from Elias Fausto was inoculated on tomato accesses and also, the variety ‘Alambra’ was used as a positive control. The experiments delineation was randomized and the plant reaction was evaluated by presence and type of symptoms, and also by positive and negative results after back inoculation and serological tests (PTA-ELISA), and by analysis of χ2 using the ratios between symptomatic and asymptomatic plants with positive or negative results in ELISA. It was verified that most evaluated accesses were tolerant to PVYº-1, but the wild species L. peruvianum B, LA-371-2 and radiated 1C had a great number of asymptomatic plants with negative results by ELISA, constituting potential sources of genes of resistance against PVY in tomatoes.
Lycopersicon spp.; Genetic resistance; Potato virus Y; PVYº-1
