Studies on the reaction in tissue culture of tomato genotypes under biotic stress
Plant regeneration in vitro from virus-infected somatic tomato (<em>Lycopersicon</em> sp.) tissue was performed. Regeneration experiments were started after the determination of virus presence, using enzyme-linked immunosorbent assay, in leaves used as a source of explants. Leaf explants infected with selected strains of tomato mosaic <em>Tobamovirus</em> or cucumber mosaic <em>Cucumovirus</em> respectively, were cultured on a standarised MS agar medium to induce adventitious shoots, which were afterwards excised, rooted in vitro and cultured to plants. Explants were also screened for their ability to produce callus. Diverse effects of viral infection, ranging from stimulation to inhibition of callus formation and of morphogenesis rate, were observed. The health condition of the tissue proved to affect regeneration potential of <em>Lycopersicon esculentum</em>, whereas wild accesions did not react in that case so distinctly. In cultivated tomato was encountered the decline in competence to reproduce shoots adventitiously in infected tissue. There was also relationship between donor plant health condition and adventitious root formation in regenerated shoots. Experiments with short-term cultures of <em>L. esculenum</em> reveled also that a certain number of shoots regenerated from diseased tissue can be virus-free.