Plant Tissue Culture

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Plant tissue culture is the technique of growing plant cells, tissues, organs, seedsor other plant parts in vitro, i.e., in glass under sterile environment and under controlled physical, chemical and nutritional conditions.

Plant Tissue Culture Terminology

Aseptic---Free of microorganisms.
Culture--- plant growing in vitro.
Explant---Tissue taken from its original site and transferred to an artificial medium for growth or maintenance
Totipotency---A cell characteristic in which the potential for forming all the cell types in the adult organism are retained
Aseptic Technique---Procedures used to prevent the introduction of fungi, bacteria, viruses, mycoplasma or other microorganisms into cultures.
Agar---a polysaccharide powder derived from algae used to gel a medium. Agar is generally used at a concentration of 6-12 g/liter
Autoclave---A machine capable of sterilizing wet or dry items with steam under pressure. Pressure cookers are a type of autoclaves.
Callus---An unorganized, proliferate mass of differentiated plant cells, a wound response.
Chemically Defined Medium---A nutritive solution for culturing cells in which each component is specifiable and ideally of known chemical structure.
Clone---Plants produced asexually from a single source plant.
Clonal Propagation---Asexual reproduction of plants that are considered to be genetically uniform and originated from a single individual or explant.
Contamination---Being infested with unwanted microorganisms such as bacteria or fungi.
Detergent---Increasing the efficiency of sterilization.
Differentiated---Cells that maintain, in culture, all or much of the specialized structure and function typical of the cell type in vivo. Modifications of new cells to form tissues or organs with a specific function.
Undifferentiated---With plant cells, existing in a state of cell development characterized by isodiametric cell shape, very little or no vacuole, a large nucleus, and exemplified by cells comprising an apical meristem or embryo
Hormones---Growth regulators, generally synthetic in occurrence, that strongly affects growth (i.e. cytokinins, auxins, and gibberellins).
Internode---The space between two nodes on a stem
Media---Plural of medium
Medium---A nutritive solution, solid or liquid, for culturing cells.
Micropropagation---In vitro Clonal propagation of plants from shoot tips or nodal explants, usually with an accelerated proliferation of shoots during subcultures.
Node—A part of the plant stem from which a leaf, shoot or flower originates.
Passage---The transfer or transplantation of cells or tissues with or without dilution or division, form one culture vessel to another.
Passage Number---The number of times the cells or tissues in culture have been subcultured or passaged.
Regeneration---In plant cultures, a morphogenetic response to a stimulus that results in the products of organs, embryos, or whole plants.
Somaclonal Variation---Phenotypic variation, either genetic or epigenetic in origin, displayed among somaclones.
Somaclones---Plants derived from any form of cell culture involving the use of somatic plant cells.
Sterile Techniques---The practice of working with cultures in an environment free from microorganisms.
Subculture---See “Passage”. With plant cultures, this is the process by which the tissue or explant is first subdivide, then transferred into fresh culture medium.
Coconut milk---The liquid endosperm of coconut contain the cytokinin zeatin and will support the continued cell division of mature cells, leading to the formation of callus
Horizontal laminar flow unit---An enclosed work area that has sterile air moving across it. The air moves with uniform velocity along parallel flow lines. Room air is pulled into the unit and forced through a HEPA (High Energy Particulate Air) filter, which removes particles 0.3 μm and larger.
Adventitious---Developing from unusual points of origin, such as shoot or root tissues, from callus or embryos, from sources other than zygotes.
Pathogen---A disease-causing organism.
Pathogenic---Capable of causing a disease

Characteristics of plant cells that make them amenable to propagation via tissue culture

Plant cells are totipotent
The normal pattern of plant development is induced to break down (dedifferentiation) through hormone treatment(s) in the growth medium, giving rise to callus (non-differentiated cell mass)
Adventitious roots, shoots, and/or embryo formation can be induced through manipulation of hormones in the growth medium (redifferentiation)
Callus can also grow continuously as single cells or small clumps of cells (e.g. suspension cultures)