Plant Tissue Culture

Plant Tissue Culture

Plant Tissue Culture (PTC) is the technique of cultivating undifferentiated plant cells, tissues, or organs on synthetic nutrient media under aseptic (sterile) conditions and controlled physical environments. This technique exploits the unique property of plant cells called totipotency, which is the ability of a single vegetative plant cell to divide and differentiate into any type of specialized cell or regenerate into a whole plant. PTC serves as a crucial tool in both basic botanical research and commercial applications such as crop improvement, micropropagation, and production of secondary metabolites. The process involves isolating a plant part called an explant, sterilizing it, and growing it on a nutrient medium optimized for growth and development. Controlled conditions of light, temperature, humidity, and asepsis ensure successful culture growth and regeneration.

• PTC involves cultivation of plant cells, tissues, or organs on artificial media.
• Totipotency is the fundamental property enabling regeneration of whole plants from single cells.
• Aseptic conditions prevent microbial contamination during culture.
• PTC is used for research and commercial propagation of plants.
• Explants can be any plant part such as leaf, meristem, embryo, cotyledon, or hypocotyl.
• Controlled physical conditions like light, temperature, and humidity are essential.
• 📌 Plant Tissue Culture: In vitro cultivation of plant cells or tissues under sterile conditions.
• 📌 Totipotency: Ability of a plant cell to regenerate into a whole plant.
• 📌 Explant: Plant tissue or organ used as starting material for culture.

7.1 Historical Perspective

The historical development of Plant Tissue Culture began in the 19th century with German scientists Theodor Schwann and Matthias Schleiden who established the cell as the basic unit of life capable of division and growth. In the 1890s, Gottlieb Haberlandt, regarded as the 'Father of Plant Tissue Culture', proposed that fully differentiated plant cells could be cultured on artificial nutrient media to achieve continuous cell division and regeneration. He laid down principles such as the ability of plant cells to resume growth and regenerate embryos from vegetative cells. Between 1902 and the 1930s, isolated plant tissues like root and shoot tips were cultured successfully. The discovery that vitamins and natural auxins are essential for growth on synthetic media boosted PTC research. From the 1940s to 1970s, improvements in nutrient media, including the use of coconut water and other natural supplements, enhanced tissue culture success. The use of adenine, kinetin, and phosphate in the 1950s led to the initiation of cultures from non-meristematic tissues and shoot/root production. The morphogenic fate of cultured cells was found to depend on the auxin to cytokinin ratio, with high auxin favoring rooting, high cytokinin favoring shooting, and intermediate levels promoting callus proliferation. The Murashige and Skoog (MS) medium, developed in 1962, became the most widely used nutrient medium for plant tissue culture. **Table on page 3 (17×2)** | 1902 | Gottlieb Haberlandt proposed that plant cells can be cultured on artificial media and developed the concept of in vitro cell culture. | | --- | --- | | 1904 | Hanning initiated work on excised embryo culture and later cultured embryos from several cruciferous species. | | 1922 | Kotte and Robbins suggested root and stem tips as possible explants to initiate in vitro tissue culture. | | 1926 | Went discovered the first plant growth hormone, i.e., Indole Acetic Acid (IAA). | | 1934 | The role of vitamin B as growth supplement in plant tissue culture was reported by White. He could successfully establish continuous growing cultures from tomato root tips. | | 1937 | White formulated the first synthetic plant tissue culture medium (WM). | | 1941 | Johannes Van Overbeek introduced coconut water as a media component and demonstrated its beneficial effects on in vitro tissue culture. | | 1946 | Ball raised whole plants from shoot tips of Lupinus. | | 1954 | Muir successfully induced cell division in mechanically isolated single cells. | | 1955 | Skoog and Miller reported the discovery of Kinetin, which is a type of cytokinin and promotes cell division. | | 1957 | Skoog and Miller described chemical control hypothesis of root and shoot differentiation by manipulating the ratio of concentrations of auxin and kinetin. | | 1962 | Murashige and Skoog formulated MS medium with higher salt concentrations. | | 1964 | Guha and Maheshwari produced the first androgenic haploid Datura plant by anther culture. | | 1971 | Protoplasts were subcultured in vitro, and plants were regenerated from their culture. | | 1972 | Protoplast from two different species of Nicotiana were isolated, fused together and somatic hybrids were generated successfully. | | 1976 | Gynogenic haploid plants were successfully cultured from unfertilised ovaries of barley by San Noeum. | | 1978 | Melchers and colleagues produced ‘Pomato’, which was a hybrid of potato and tomato, and was produced through somatic hybridisation. | **Table on page 4 (10×2)** | 1981 | The term ‘Somaclonal Variations’ was introduced by Larkin and Scowcroft, for the genetic variations introduced during the plant tissue culture. | | --- | --- | | | Horsh and colleagues produced transgenic tobacco plants. Leaf discs were used as explants and were cultured with *Agrobacterium tumefaciens*. | | | Klien and colleagues developed high-velocity microprojectile-based DNA delivery ‘biolistic gene transfer’ method for plant transformation. | | 1987 | Y. Fujita and Mamoru Tabata established *Lithospermum erythrorhizon* cell cultures for the shikonin production and commercialised it. | | | Transgenic Bt-cotton was produced by Monsanto and in 2000, it was approved by the Government of India for commercial production in India. | | 1993 | Kranz and Lorz produced fertile maize plants through *in vitro* fertilisation. | | | Plant tissue culture free plant transformation method ‘*Arabidopsis* Floral-dip’ was developed. | | | Transgenic rice engineered for the production of provitamin A (beta-carotene) in rice endosperm was developed and is called ‘Golden Rice’. | | | The first plant produced enzyme was approved for human use. It is used to treat a rare lysosomal storage disease called Gaucher’s Disease. | | | Somatic embryogenesis was introduced in plant transformation through the embryonic genes. | **Table on page 15 (13×4)** | S. No. | Product Name | Plant Source | Uses | | --- | --- | --- | --- | | 1. | Artemisin | Artemisia sp. | Antimalarial | | 2. | Azadirachtin | Azadirachta indica (Neem) | Insecticidal | | 3. | Berberine | Coptis japonica | Antibacterial, anti-inflammatory | | 4. | Capsaicin | Capsicum annum (Chilli) | Rheumatic pain treatment | | 5. | Codeine | Papaver sp. | Analgesic | | 6. | Digoxin | Digitalix lanata | Cardiac tonic | | 7. | Diosgenin | Dioscorea deltoidei | Antifertility | | 8. | Scopolamine | Datura stramonium | Antihypertensive | | 9. | Quinine | Cinchona officinalis | Antimalarial | | 10. | Shikonin | Lithospermum erythrorhizon | Antimicrobial | | 11. | Taxol | Taxus sp. | Anticarcinogenic | | 12. | Vincristine | Cathranthus roseus | Anticarcinogenic |

• Theodor Schwann and Matthias Schleiden identified the cell as the basic unit of life.
• Gottlieb Haberlandt pioneered the concept of in vitro plant cell culture in 1902.
• Vitamins and natural auxins were found necessary for tissue growth on synthetic media.
• Coconut water and other natural supplements enhanced embryo development in cultures.
• Auxin and cytokinin ratios control organogenesis in cultured cells.
• Murashige and Skoog (MS) medium is the most widely used nutrient medium.
• 📌 Auxin: Plant hormone promoting cell elongation and rooting.
• 📌 Cytokinin: Plant hormone promoting cell division and shoot formation.
• 📌 Murashige and Skoog (MS) Medium: A nutrient medium formulated for plant tissue culture.