What is plant tissue culture?

           Plant tissue culture (PTC) is the art and science of multiplying plants or plant parts (such as organs, tissues, cells, pollens, sores and embryos) under controlled conditions of light, temperature and humidity in an optimal nutrient medium under aseptic conditions in a glass vessel.

            Even a single cell has the potency to perform all the metabolic activities to form an independent plant. This phenomenon is known as totipotency. This is successfully used in tissue culture. Infinite number of plants can be produced from single explants in a span of time, irrespective of natural conditions. The seedlings will be genetically ‘true copies’ of the mother plant. That means, genetic purity can be maintained as far as required, in every seeding, which is almost impossible in conventional means of propagation.

            PTC has been successfully tried in almost all plant varieties. Some plants like orchids produce millions of non-endosperm us seeds in a single fruit, which cannot be cultivated in natural conditions. When grown through PTC, they have more than 75 percent germination. In the medium in which the plants are cultivated all the required micro and macro nutrients and vitamins are added. Since the growth inside the glass vessel is heterophic, a carbon source in the form of sucrose is added to the medium. PTC has been commercialized and is a lucrative business.

            In PTC, a very small tissue from a parent plant called as explants is placed in a test tube in a nutrient medium. The tissue may be taken from any part of the plant, that is, root, stem, leaf, anther or embryo. This is because all plant cells possess totipotency meaning a single cell can give rise to an entire plant.

            The nutrient medium used in tissue culture consists of sucrose apart from mineral salts and vitamins. Plant hormones such as Auxins are used to help growth and cell division. The solidifying agent, agar makes the medium semi solid otherwise the culture is done suspension. The inoculated tubes are kept in an incubator to maintain sterile conditions and controlled temperature and light. After 2-3 weeks of incubation an irregular mass of cells called callus develops, which on sub culturing gives rise to small plantlets. These are potted and maintained in a green house and subsequently transferred to the field. PTC is aimed at engineering crop plants for good traits.