Plants utilize two modes of reproduction: sexual reproduction, in which there is a genetic exchange with another plant, and vegetative reproduction, in which a part of the parent plant grows into identical offspring. By harnessing the potential of vegetative reproduction, horticulturalists obtain exact copies of a favorite plant. One method that they use is tissue culture.
As the Washington State University Extension points out, most gardeners have practiced a rudimentary form of tissue culture whenever they swap cuttings from favorite plants with a friend. These methods capitalize on the same ability of plants to grow a whole plant from a single cell. However, when most people talk about tissue culture, they are referring to micropropagation, a technique where small amounts of plant tissue can create hundreds or thousands of identical plants.
If you've ever planted the seeds from a favorite plant and been disappointed with the results, then you know that plants don't always resemble the parent plant. Tissue culture allows horticulturalists to obtain exact copies of plants and produce large numbers of offspring. When plants don't grow easily from seed or have bacterial or viral infections, micropropagation becomes an especially attractive solution.
Micropropagation begins by taking a tissue sample from the parent plant, usually from the rapidly growing tissue at the tips of roots and stems. The tissue extraction is called the explant, and it is sterilized and grows on a gel medium in a sterile in vitro environment. Plant growth hormones introduced into the growing medium cause different parts, such as the roots, to grow. Once the plant grows, the horticulturalist transplants it to growing medium and gradually adapts it to normal growing conditions.
Due to precision needed to maintain a proper sterile growing environment and the expense associated with that, micropropagation is out of reach for most home gardeners, according to Ohio State University Extension. Traditional cuttings and divisions prove much more feasible for the hobbyist.
Micropropagation promised great potential for growing plants in large numbers and, in some instances, has proven fruitful. However, contamination by pathogens that prefer the same growing environment as explants causes problems. In addition, each plant species has its particular growing needs. Not all of these are yet known, making micropropagation ineffective for some species.