Tissue Culture

For a variety of purposes, plant cells, tissues, organs, and whole plants can be grown in labware containing a medium composed of defined molecules. Tissue culture media provide water, minerals, vitamins, hormones, carbon sources, and antibiotics depending on the plant material being cultured. Since most living plant cells are totipotent , scientists can manipulate the medium to regenerate whole plants from even a single genetically engineered plant cell or from a cluster of cells from a rare plant. Hormones in the medium determine what plant parts form from the cells (callus) in the culture: Auxins stimulate root formation and cytokinins stimulate shoot formation. The medium may contain agar, agarose, phytagel, or other polysaccharides to form a semisolid gel to support the plant tissue. The container must be colorless if photosynthesis is to be supported, and the light source should not be too intense to avoid the greenhouse effect inside the container. If the container is not ventilated, a carbon source such as sucrose will have to be used. Tissues must be subcultured periodically to avoid solute concentration buildup if the container is ventilated. Antibiotics may be used to keep the culture clear of bacteria, fungi, or other contaminants or to select for genetically engineered cells. Tissue culture techniques are also used to generate large numbers of genetically identical plants for agricultural applications, or to generate additional plants of rare or endangered species.

see also Genetic Engineering; Propagation; Reproduction, Asexual; Transgenic Plants.

Ross Koning

Bibliography

Hopkins, W. G. Introduction to Plant Physiology, 2nd ed. New York: John Wiley & Sons, 1999.

Raven, Peter. H., Ray F. Evert, and Susan E. Eichhorn. Biology of Plants, 6th ed. New York: W. H. Freeman and Co., 1999.

tissue culture The growth of the tissues of living organisms outside the body in a suitable culture medium. Culture (or nutrient) media contain a mixture of nutrients either in solid form (e.g. in agar) or in liquid form (e.g. in physiological saline). Tissue culture has proved to be invaluable for gaining information about factors that control the growth and differentiation of cells. Culture of plant tissues has resulted in the regeneration of complete plants, enabling commercial propagation (e.g. of orchids) and – through culture of meristem tissues – the production of virus-free crop plants. See also explantation; micropropagation; tissue engineering.

tissue culture Individual cells of an organism, that are grown in a sterile medium containing the nutrients the cells require. The technique can yield information about the nutritional requirements of individual cells, and whole plants can often be grown from tissue samples or even from single cells. In gene banks, tissue culture methods may be used to store plants, in a non-bulky growth phase, if their seeds do not remain viable for long periods of time. It is also possible to save crop plant varieties from extinction through an attack by pathogens by isolating and culturing meristematic tissue (see MERISTEM), which is rarely attacked. Crosses can also be made between otherwise incompatible plants by removing embryos before they are aborted and growing them by this method.

tissue culture In biology, artificial cultivation of living tissue. Tissue culture in laboratories is used for biological research or to help in the diagnosis of diseases. It is also used as a means of propagating plant clones. See also genetic engineering

tissue culture See cell culture.