Culture medium is the most important part of plant tissue culture. A successful plant tissue culture system largely relies on a right culture medium formula. Plant tissue culture media usually contains inorganic elements, organic compounds and a support matrix. Culture media provides the cultures the necessary inorganic nutrients that are usually available from soil. In addition, they also provide the cultures the necessary organic compounds such as vitamins, and carbon source, which are usually produced in plants. Sometimes, plant growth regulators are added to the medium to stimulate cell division and/or differentiation.
Another important function of a culture medium is creating a necessary environment for plants to grow. For example, solid media, functioning like the soil, provides a physical support for the cultures to keep contact with air for respiration, and for regenerated plantlets to root into. A liquid medium enables explants to keep constant, maximum contact with nutrient supplies. A selective reagent may also be included in a culture medium to restrict the growth of certain cultures. Therefore, medium formulas vary depending upon the purpose of plant tissue culture. Different media may also be used during a plant tissue culture process.