<h5 id="71-historical-perspective">7.1 Historical Perspective</h5> <ul> <li>In 1902, Gottlieb Haberlandt proposed the concept of plant cell culture on artificial media.</li> <li>In 1926, Went discovered the first plant growth hormone, Indole Acetic Acid (IAA).</li> <li>In 1934, White reported the role of vitamin B as a growth supplement in plant tissue culture.</li> <li>In 1937, White formulated the first synthetic plant tissue culture medium (WM).</li> <li>In 1955, Skoog and Miller reported the discovery of Kinetin, a type of cytokinin that promotes cell division.</li> <li>In 1962, Murashige and Skoog formulated MS medium with higher salt concentrations.</li> <li>In 1971, protoplasts were subcultured in vitro and plants were regenerated from their culture.</li> <li>In 1978, Melchers and colleagues produced ‘Pomato’, a hybrid of potato and tomato, through somatic hybridisation.</li> <li>In 1984, Horsh and colleagues produced transgenic tobacco plants using Agrobacterium tumefaciens.</li> <li>In 1990, transgenic Bt-cotton was produced by Monsanto and approved for commercial production in India.</li> <li>In 2000, transgenic rice engineered for the production of provitamin A was developed and called ‘Golden Rice’.</li> <li>In 2012, the first plant-produced enzyme was approved for human use to treat Gaucher’s Disease.</li> <li>In 2016, somatic embryogenesis was introduced in plant transformation through embryonic genes.</li> </ul> <p>======</p> <h5 id="72-plant-cell-and-tissue-culture-techniques">7.2 Plant Cell and Tissue Culture Techniques</h5> <ul> <li>Plant cell and tissue culture techniques involve growing plant cells, tissues or organs in a controlled environment, under sterile conditions, on nutrient media.</li> <li>The response of different plant organs varies for in vitro culture; immature embryos are more responsive than apical meristem, which are generally more responsive than leaf explants.</li> <li>Plant regeneration in cultures can occur through two morphogenetic pathways: organogenesis and somatic embryogenesis. Organogenesis involves the formation of various vegetative organs from cells or tissues, while somatic embryogenesis involves the formation of an embryo from somatic cells.</li> <li>The step-by-step procedure for in vitro plant tissue cultures using tomato cotyledons as explants includes selection of nutrient media, surface sterilisation of the explant, inoculation of explants onto the nutrient media, growing the cultures, transfer of growing cultures onto suitable media to regenerate shoots, excision of regenerated shoots and transfer onto the rooting medium, and transfer of plantlets to sterilised soil in pots for hardening.</li> <li>Basic requirements for plant tissue culture include a washing area, various media components for the preparation of Nutrient Media, a facility to sterilise nutrient media and store media at low temperatures, and facilities for maintenance of cultured tissues in aseptic conditions under controlled environment.</li> </ul> <p>======</p> <h5 id="73-nutrient-media">7.3 Nutrient Media</h5> <ul> <li>Nutrient media for in vitro plant cultures contain inorganic components, organic supplements, carbon source, plant growth hormones, gelling agents, and sometimes antibiotics.</li> <li>Inorganic components include macronutrients like C, Ca, H, K, Mg, N, O, P, and S, and micronutrients like B, Co, Cu, Fe, Mn, Mo, and Zn.</li> <li>Organic supplements include amino acids (e.g., arginine, asparagine, glycine, proline) and vitamins (e.g., thiamine, nicotinic acid, myoinositol).</li> <li>Sucrose is the preferred carbon source, used at a concentration of 2-5%. Other sources of carbon are glucose, fructose, and mannose.</li> <li>Plant growth hormones, required in minute quantities, are auxin, cytokinin, gibberellin, abscisic acid, and ethylene; auxins and cytokinin are most commonly used in plant tissue culture.</li> <li>The pH of the nutrient media is adjusted to about 5.8 to 6.0. Agar is the most commonly used gelling agent. Antibiotics can be added to suppress bacteria and antifungal agents for mold infections.</li> </ul> <p>======</p> <h5 id="74-culture-types">7.4 Culture Types</h5> <ul> <li> <p>The text provides a table of concentrations for various substances used in plant cultivation. Macronutrients include:</p> </li> <li> <p>$MgSO_4 o cdot 7 H_2O$ at 750 mg l^{-1} and 370 mg l^{-1}</p> </li> <li> <p>$KH_2 PO_4$ at 170 mg l^{-1}</p> </li> <li> <p>$NaH_2 PO_4 o cdot H_2 O$ at 19 mg l^{-1}</p> </li> <li> <p>$KNO_3$ at 80 mg l^{-1} and 1900 mg l^{-1}</p> </li> <li> <p>$NH_4 NO_3$ at 1650 mg l^{-1}</p> </li> <li> <p>$CaCl_2 o cdot 2 H_2 O$ at 440 mg l^{-1}</p> </li> <li> <p>Micronutrients include:</p> <ul> <li>$H_3 BO_3$ at 1.5 mg l^{-1} and 6.2 mg l^{-1}</li> <li>$MnSO_4 o cdot 4 H_2 O$ at 5 mg l^{-1} and 22.3 mg l^{-1}</li> <li>$ZnSO_4 o cdot 7 H_2 O$ at 3 mg l^{-1} and 8.6 mg l^{-1}</li> <li>$Na_2 MoO_4 o cdot 2 H_2 O$ at 0.025 mg l^{-1}</li> <li>$CuSO_4 o cdot 5 H_2 O$ at 0.01 mg l^{-1}</li> <li>$CoCl_2 o cdot 6 H_2 O$ at 0.025 mg l^{-1}</li> <li>$Kl$ at 0.75 mg l^{-1} and 0.83 mg l^{-1}</li> <li>$FeSO_4 o cdot 7 H_2 O$ at 27.8 mg l^{-1}</li> <li>$Na_2 EDTA o cdot 2 H_2 O$ at 37.3 mg l^{-1}</li> </ul> </li> <li> <p>Organic supplements include sucrose at 20 g l^{-1} and 30 g l^{-1}, and various vitamins and other substances.</p> </li> <li> <p>The text also discusses the cultivation of plant organs under laboratory conditions, including root culture, anther culture, embryo culture, and callus culture.</p> </li> <li> <p>Single cells can be isolated from callus or other plant parts and cultured in liquid medium, referred to as cell suspension culture. These single cells can be used for various studies and applications.</p> </li> </ul> <p>======</p> <h5 id="75-applications-of-plant-cell-and-tissue-culture">7.5 Applications of Plant Cell and Tissue Culture</h5> <ul> <li>Artemisin, found in Artemisia sp., is used as an antimalarial.</li> <li>Azadirachtin, from Azadirachta indica (Neem), has insecticidal properties.</li> <li>Berberine, in Coptis japonica, is antibacterial and anti-inflammatory.</li> <li>Capsaicin, from Capsicum annum (Chilli), is used in treating rheumatic pain.</li> <li>Codeine, found in Papaver sp., is an analgesic.</li> <li>Digoxin, from Digitalis lanata, is a cardiac tonic.</li> <li>Diosgenin, in Dioscorea deltoidei, has antifertility properties.</li> <li>Quinine, from Cinchona officinalis, is an antimalarial.</li> <li>Shikonin, found in Lithospermum erythrorhizon, is antimicrobial.</li> <li>Taxol, from Taxus sp., is an anticarcinogenic.</li> <li>Vincristine, in Cathranthus roseus, is an anticarcinogenic.</li> </ul> <p>======</p>