REGENERATION OF VIRUS-FREE PLANTS THROUGH IN VITRO CULTURE.

This article deals with the theories, methodology and practices of in vitro virus elimination. Viruses may be eradicated from infected stocks through meristem or callus cultures due to the low titre, or even absence, of viruses in plant meristems and what might be called ″the viral elimination power of in vitro incubation″ . Virus-free tissue sectors may arise from calli of infected plants. From such sectors virus-free plants may regenerate. Nevertheless, the frequently occurring chromosome abnormalities in callus cultures may become a strong drawback for regenerating virus-free plants from callus. The commonly used testing methods are briefly described. Methods employed for rapid in vitro mass-cloning of virus-free plants include: multiple shoot formation, in vitro layering, adventitious organogenesis, and in vitro storage organ induction. The resulting virus-free clones frequently exhibit an improved yield and quality.