Q.Describe the plant tissue culture process in brief.

Tissue culture uses cell totipotency: a sterile explant grown on nutrient medium forms a callus, which is then hormonally induced to regenerate complete plantlets, allowing rapid clonal multiplication.

Plant tissue culture (micropropagation):

1. Basis – totipotency: Every living plant cell has the capacity to regenerate into a whole plant. This property, totipotency, is the foundation of tissue culture.
2. Explant and sterilisation: A small part of the plant — the explant (e.g. a bit of shoot tip, leaf or node) — is cut and thoroughly surface-sterilised to prevent microbial contamination.
3. Culture medium: The explant is placed on a sterile nutrient medium (e.g. MS medium) containing a carbon source (sucrose), inorganic salts, vitamins and plant growth regulators (hormones), under aseptic conditions.
4. Callus formation: On this medium the cells divide to form an undifferentiated mass of cells called the callus.
5. Organogenesis / differentiation: By adjusting the ratio of the hormones auxin and cytokinin, the callus is induced to differentiate — a higher cytokinin ratio favours shoots, a higher auxin ratio favours roots — producing small plantlets.
6. Hardening and transfer: The regenerated plantlets are gradually acclimatised (hardened) and finally transplanted to soil.

Since all plants come from one parent tissue, they are genetically identical clones — useful for mass multiplication and producing virus-free (disease-free) plants from meristem tips.

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