Q.Virus-free plants can be obtained by

Micropropagation (in vitro tissue culture / clonal propagation) — small explants of an endangered plant are cultured on nutrient medium to rapidly generate large numbers of genetically identical, disease-free saplings.

Micropropagation via tissue culture produces many identical clones from one endangered plant.

Micropropagation is a technique of plant tissue culture in which a small piece of plant tissue (explant — meristem, shoot tip, or even a single cell) is grown aseptically on a nutrient medium containing appropriate hormones. The totipotent cells divide and differentiate to regenerate complete plantlets, which are genetically identical clones of the parent. Because thousands of plantlets can b …

The shoot apical meristem is virtually free of viruses even in an infected plant, so culturing it in vitro produces virus-free clones.

Even when a plant is systemically infected with a virus, the actively dividing cells of the shoot apex (apical meristem) usually remain free of the virus because the virus's rate of multiplication/movement is slower than the rate of growth of the meristem, and the meristem lacks a well-developed vascular system through which viruses typically spread. By excising just this virus-free meristematic tip and growing it in vitro using tissue-culture techniques (meristem culture), a large number of virus-free plants can be regenerated and propaga …