Tracing the history of plant-tissue culture, one can identify the series of land mark discoveries in this field to be originating from the proposal of cell as the basic unit of form and function of an organism.

• Schleiden and Schwann in 1839 propounded the cell theory and visualized its autonomy and potential to regenerate into a whole organism.
• Vochting’s classical experiments in 1878 demonstrated the polarity of plant cuttings to regenerate shoots or roots depending on their relative position on the stem.
• Classical experiments of Gottleib Haberlandt, a German botanist in 1902 on isolated single plant cells demonstrated their growth in size in basic salt solution (Knops Media) supplemented with sucrose. He is now considered the “Father of Plant-Tissue Culture” and he had rightly proposed the ability of plant cells to resume uninterrupted plant growth and even form artificial embryos from vegetative cells.
• Successful growth to maturity of nearly mature embryos of radish species on simple media of mineral salts and sugar solution by Hanig in 1904, established the foundation of later successful embryo culture technique.
• Laibach in 1929 reared embryos from nonviable seeds of artificial hybrids of Linum species on nutrient medium, opening up possibility of culturing aborted embryos of several hybrids.
• Van Overbreek in 1941 succeeded in culturing young embryos on media supplemented with embryo sac fluid-coconut milk.
• As suggested by Haberlandt, his student Kotte and Robbins, both working independently, cultured growing root tips in 1922.
• Modifying media composition, White in 1934 managed to continuously maintain tomato root tips in culture for about 34 years. His media constituted of inorganic salts, sucrose, and yeast extract, which was later replaced with vitamins B6, B2, and nicotinic acid. Recognition of importance of B vitamins in plant growth was an important milestone, as was the first identification of use of Indole acetic acid (IAA) for enhancing growth of Salix cambium by Gauthret in the same year (1934).
• IAA was earlier discovered in 1926 as a plant growth regulator by Fritz Went. In 1939 White reported similar results with Nicotiana species hybrid tumor tissue as had Nobecourt with carrot cultures in 1937. Media used by Gauthret, White, and Nobecourt went on to become the basic tissue culture media used in later years up to this day with modifications.
• Skoog in 1944 and Skoog and Tsui later in 1951, identified the importance of vascular tissue in inducing cell division in tobacco pith cells in media supplemented with adenine and phosphate.
• Jablonski and Skoog found that pith tissue could grow even without the presence of vascular tissue when DNA was added to the media. In 1955 Miller and workers isolated the first cytokinin called kinetin from DNA of herring sperm. These experiments on tobacco pith cultures showed that high concentrations of IAA and such auxins promoted rooting and high concentrations of kinetin initiates shooting and bud formation in cultures. At equal concentrations, the tissue grows in an unorganized manner forming callus tissue.
• In 1962 Murashige and Skoog showed that growth of tobacco tissue is enhanced 5 times when media salt concentration was 25 times as much as Knops media. Today Murashige & Skoog (MS) medium has great commercial application in tissue culture.
• In 1953 Muir was successful in growing individual cells mechanically separated from cultures shaken to disperse aggregates of callus tissue. These cells from Tagetes and Nicotiana species underwent division on a filter paper nursed with established callus culture underneath.
• It was possible to observe cultured single cells growing in hanging drops of tissue-conditioned media, due to the work of Jones and his group in 1960.
• In the same year, Bergmann developed a technique for cloning large numbers of single cells of higher plants by filtering suspension cultures. This formed the basis of the plating technique widely used later for cloning isolated single protoplasts.
• From isolated cells of colonies of hybrid from Nicotiana glutinosa and N. tabacum, Vasil and Hildebrandt regenerated whole plantlets in 1965.
• Instead of cells from actively growing tissues in cultures, mature mesophyll cells from Macleaya species were successfully cultured by Kohlenbach in 1966.
• In the same year, Steward reported induction of somatic embryos from free cells in carrot suspension cultures. Thus, so far the prediction of Haberlandt to regenerate whole plants from single cells was realized by way of shoot and root differentiation or embryogenic development from cultured tissue cells. Such a possibility of regenerating whole plants from single somatic cells found great applicability in both plant propagation and later in genetic engineering.
• Further detailed studies by Bingham, Saunders, Reisch, Bhojwani, Green, Philips, and Vasil from 1970–1980 revealed that while it was easy to raise somatic embryos from plants like carrot, cereals, and legumes do not respond similarly. Regeneration potential was reported to be genetically controlled and proper genotype selection and physiological state of explant were important factors.
• With successful growth of plant cells in suspension in a liquid medium, began attempts to generate plant-derived chemicals in vitro. First large-scale production of plant secondary metabolites from cultured plant cells was reported by Tulecke, Nickell, and Routien in 1956–58 on Ginkgo, Rose, and Lolium species. Despite problems of slow growth, genetic instability, intracellular accumulation of generated compounds and the like, work of Kaul and Staba in 1967 and Zenk in 1978 showed generation of secondary metabolites in cultures in much larger quantities than whole plants.
• Shikonin, a red-coloured dye from tissue cultures of Lithospermum erythrorhizon was the first product to be commercialized.
• Next the technique of immobilization of secondary metabolite generating plant cells was developed by Brodelius and his group in 1979. Larger quantities of plant cellular mass could be used for longer periods making harvesting of the generated secondary metabolites much easier than from suspension cultures.
• Ball in 1946 raised whole plants of Lupinus and Trapaeolum from shoot tip culture. This technique found extensive practical application in terms of rapid propagation of large number of genetically identical plants from a very small portion of an explant. This soon became a regular method of propagation of orchids and many other plant species including flowering and fruiting plants began to be cloned. Genetic variation found in plants raised from cultured cells was beneficially utilized for specifically raising resistant, high yield, or novel variants/strains with respect to secondary metabolite composition.
• Nay and Street by regenerating plants from frozen carrot cells in 1973 gave impetus to the idea of freeze preservation of valuable germplasm.
• Morel and Martin in 1952 cultured virus free shoot tip meristem of virus infected Dahlia plants and generated disease free plants. Today this technique of micrografting to raise pathogen-free plants from infected stocks is of great agronomic and horticultural importance.
• In vitro culturing of pollen grains together with excised ovules resulted in in vitro or test tube fertilization of ovules by the germinated pollen due to the work of Maheswari and Kanta in 1960–1962. This technique was successfully used to overcome sexual incompatibility between species and genera and also to produce rare hybrids.
• By growing large numbers of androgenic haploid plants from cultured pollen grains of Datura innoxia in 1966, Guha and Maheswari opened up the possibility of introduction of newer varieties of rice, wheat, and tobacco.
• A significant breakthrough in plant-tissue culture was isolation of protoplasts from plant cells by enzymatic cell wall degradation by Cocking in 1960. These naked cells without cell wall could be fused to generate somatic hybrids as reported by Carlson in 1972 with tobacco species. The reconstituted cell was shown to regenerate a new wall and continue with cell division. Isolated protoplasts were shown to be totipotent and with protoplast fusion, it was possible to generate genetically altered somatic cells or hybrids. By raising whole plants from such somatic hybrids, it became possible to generate agronomically useful variants or hybrids. Today protoplast fusion techniques have become much more technologically sophisticated with contributions from advances in genetic engineering.
• Isolation of restriction endonuclease enzymes by Smith and Nathans in 1970 and reverse trasncriptase by Baltimore enabled insertion of foreign genes into native DNA of plant cells thus enabling their genetic modification.
• This heralded a new research area of genetic engineering, and by 1972 in vitro recombinant DNA virus was reconstructed by Paul Berg. This tool made possible construction of human insulin using recombinant bacteria.
• Observation of crown gall disease causing gram negative soil bacteria Agrobacterium tumefaciens in gall forming plants by Zaenan and group in 1974 led to the demonstration of the transfer and integration of a large plasmid from the bacterium into the plant cell genome. This induced the formation of excessive epidermal cell growth and hence, gall formation.
• Due to the work of Chitton et al., in 1977 and Barton et al., in 1983 it became possible to insert heterologous DNA into this bacterial plasmid, which was transferred by it into plants thus producing a genetically altered plant. This gave birth to the production of transgenic plants pioneered by the generation of transgenic tobacco plants by Horsh et al., in 1984. Several other gene transfer methods such as bolistic gene transfer, eletroporation, microinjection, and particle gun were introduced and many genetically improved plant varieties with economically useful traits were developed.

As predicted by Haberlandt, experiences with plant-tissue culture greatly expanded our understanding about the “inter relationships and complementary influence to which cells are exposed to within a multicellular organism.” This was reflected in extensive commercial applications in several areas of life sciences including production of improved crop varieties, biotransformation of secondary metabolites, proptoplast generated somatic hybrids, genetically transformed transgenic plants, rapid propagation of genetically uniform plants, and germplasm storage.