Correlations between symptoms and DAS - ELISA values in two sources of resistance against tomato spotted wilt virus

RESUMO

The commercial tomato, "Lycopersicon esculentum", cultivars Ângela Gigante I-5100 and Santa Clara (tsopovirus susceptible), the Stevens cultivar, lines and experimental hybrids (tospovirus resistant), were used a) to evaluate two sources of resistance to tospoviruses in tomato (one from "L. esculentum"/Rey de Los Tempranos, and another one from "L. peruvianum"/Stevens); and b) to verify statistically significant correlation between virus concentration determined through DAS-ELISA and symptomatology. In the Ângela GiganteI-5100 and the Santa Clara cultivars, the correlation coefficient was highly significant and the symptom average level was high, showing that in susceptible cultivars the symptom evolution is related to the virus multiplication in the plant. As for the TOM 547 and TOM 556 lines (background of Ângela Gigante I-5100 and Santa Clara, respectively), there was no statistical correlation between the symptoms and the viral particule concentration. Plants with light virus symptoms showed high absorbance values. Consequently we may assume that the resistance with 'Rey de Los Tempranos' background may be of the tolerant kind because the high virus concentration found does not necessarily relate to a high level symptoms. In the lines BPX320E 3902-01, BPX320E 3905 and BPX320F 7902 (both with Santa Clara background) only few plants showed symptoms, which can be explained by incomplete penetrance of Sw-5 gene. In the case of non-symptomatic plants, the diagnosis using DAS-ELISA revealed negative results. That outcome indicates that in some materials, where resistance is obtained from "L. peruvianum", the virus multiplication in the tissues seemed not be present.