The Assessement of Viricides Phytotoxicity used in Grapevine in Vitro Chemotherapy

The aim of the study was to evaluate the phytotoxicity of antiviral drugs ribavirin (Rib) and oseltamivir (Os) used in controlled medium, in various concentration and period of exposure in the most dangerous grapevine viruses elimination processes by in vitro chemotherapy. Grapevine shoot cultures belonging to V. vinifera L. cultivars simple infected by fanleaf virus (GFLV), leafroll associated virus serotype 1+3 (GLRaV1+3), fleck virus (GFKV) were grown on M&S (1962) basic medium supplemented with antiviral chemicals for in vitro sanitation (Panattoni et al., 2006). Thus, increasing concentrations of Rib or Os were added to the proliferating medium for several subsequent subcultures. In the end treatment, regenerated shoots were transferred on free-drug rooting M&S medium. Phytotoxicity was evaluated on in vitro drug treated plantlets regarding multiplication rate and mortality for each viricide. Leaf samples collected from regenerated acclimated plants determined as virus-free by enzyme-linked immunosorbent assay (ELISA) were subjected to biochemical analysis (polyphenols, soluble carbohydrates, chlorophyll pigments concentration). Statistical significance of differences between drug treated variants compared with the control (untreated) was analyzed by SPSS 10 for Windows, taking P<0.05 as significant according to one-way ANOVA. The increasing of the exposure to Rib induced the significant decreasing of the multiplication rate (1.4 – 1.9x) for each drug concentration and the explants registered more than 95% mortality at the highest concentration of Rib. On the other hand, Os induced an increasing proliferation of adventive buds in the beginning of exposure, without shoot elongation during the treatment. The phytotoxic effect of Rib and Os has diminished with plant transfer on free-drug rooting medium. Not significant differences between drug treated and control plants referring to the biochemical compounds have been registered. Visual observations on the experimental variants emphasized that Os had lower phytotoxicity than Rib. The phytotoxic effect should be correlated with the viruses elimination efficacy and grapevine infected genotype.