Plant Tissue Culture
Somaclonal variation and secondary metabolites
See variation and products from culture.
Body (somatic) cells slowly gather genetic changes. Normally these are not passed on through seeds. But when plants are regenerated from such cells by tissue culture, especially after long-term callus or suspension culture, the changes appear in the new plants. This is somaclonal variation, and the plants are somaclones.
It can be a bane or a boon:
- A bane when we want true-to-type clones, identical to the parent.
- A boon when somaclones are screened for useful new traits: disease-resistant sugarcane, banana and tomato, and higher-yielding wheat have been obtained this way.
Secondary metabolites are chemicals that plants do not need to survive, but that help them deal with their environment, for example to deter grazers. They include alkaloids, flavonoids, tannins, steroids, latex and resins, and they give us drugs, flavours, dyes, insecticides and fragrances.
Cultured plant cells can make them under controlled conditions, independent of the season and free of plant diseases, sometimes in larger amounts than the parent plant. 'Hairy root' cultures are used in industry. This can save plants that are being over-harvested from the wild, and make drugs cheaper.
Examples:
| Product | Use |
|---|---|
| Artemisinin | Antimalarial |
| Azadirachtin (from neem) | Insecticide |
| Quinine | Antimalarial |
| Shikonin | Antimicrobial |
| Taxol, vincristine | Anticancer |
| Digoxin | Heart disease |
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