Plant tissue culture encompasses culturing of plant parts on an artificial medium. The plant parts can be a single cell, tissue or an organ. It is also referred to as micropropagation. This was practically implemented for the first time by Haberlandt, a German scientist, in 1902. Later in 1934, Gautheret found successful results on in-vitro culture of plants. The basic key used in plant tissue culture is the totipotency of plant cells, meaning that each plant cell has the potential to regenerate into a complete plant. With this characteristic, it is used to produce genetically identical plants (clones) in the absence of fertilization, pollination or seeds.
Methods and Techniques
In plant tissue culture, plants or explants such as pieces of leave, stem or root is cultured in a specific plant medium, which contains essential plant nutrients and hormones. Other plant growth factors like light and temperature are maintained and regulated by using artificial conditions. All the procedures are conducted under sterile (aseptic) conditions. The explants then develop stem, roots and leaves. The generated plantlets are hardened before planting in outdoor conditions.
To start with plant tissue culture, one should wipe his/her hands, forceps and other equipment with alcohol or other sterilizer to prevent microbial contamination. Following this, the explants are surface sterilized by using chemical solutions such as bleach or alcohol. Though mercury chloride is an effective sterilizer, it is rarely used due to its potential toxicity. After sterilization, the explants are introduced into a plant medium, which can be either solid or liquid. The cells divide and differentiate into plant parts, thus giving rise to a complete plant.
Speaking about the plant medium, liquid type is prepared by mixing inorganic salts, organic nutrients (sucrose), vitamins, minerals and plant growth regulators (auxin and cytokinin). In addition to these ingredients, solid medium contains gelling agent (agar). Nutrient and plant hormones amount vary, depending on the objective. For example, in order to induce more roots, auxin amount should be high. the techniques include the culture of protoplast (a cell without cell wall), meristem, node, anther, ovule, embryo and seed.
Plant tissue culture has wide applications in agriculture. One major advantage is the production of disease and/or pest resistant varieties, thus indirectly increasing the crop yield. Commercially, it is used directly for the propagation of plants that are hard to propagate in natural conditions.
Horticultural plants such as orchids, roses, banana, strawberries, potatoes, apples, etc. are successfully cultured in in-vitro conditions. Plants with valuable secondary products are grown in the controlled conditions by using plant tissue culture technique. It is also used for the propagation of medicinal herbs on a large scale. With plant tissue culture, it is possible to generate virus-free plantlet of vegetatively propagated plants.
In experimental biology such as plant breeding, cell biology, biotechnology and genetics, plant tissue culture is applied in order to solve plant related problems. It allows screening of cells for the desirable characters such as early fruit bearing, disease resistance and drought resistance. Another important application is generation of a novel hybrid by crossing two distantly related species having advantageous traits. In-vitro fertilization and/or pollination of plants is possible, irrespective of the hindrances in natural conditions. Overall, it is used for the conservation of germplasm.