Wilhelm Roux, a German zoologist, made an early attempt at tissue culture in 1885, cultivating tissue from a chick embryo in a warm salt solution. However, the first real breakthrough occurred in 1907, when American zoologist Ross G. Harrison demonstrated the growth of frog nerve cell processes in a medium of clotted lymph. Following Harrison’s technique, French surgeon Alexis Carrel and his assistant Montrose Burrows improved on it, reporting their initial advances in a series of papers published in 1910–11. Tissue culture was coined and defined by Carrel and Burrows. Following that, a number of researchers were successful in cultivating animal cells using a variety of biological fluids as culture media, including lymph, blood serum, plasma, and tissue extracts. Methods were developed in the 1980s and 1990s that allowed researchers to successfully grow mammalian embryonic stem cells under artificial conditions. These breakthroughs eventually allowed for the establishment and maintenance of human embryonic stem cell lines, which advanced researchers’ understanding of human biology and facilitated progress in therapeutics and regenerative medicine.
Tissue Culture
Tissue culture is the biological research method in which fragments of tissue from an animal or the plant are transferred to an artificial environment where they can survive and function. Cultured tissue can be a single cell, population of cells, or an entire or part of an organ. Cells in culture can multiply, change size, shape, or function, exhibit specialised activity (for example, muscle cells can contract), and interact with other cells.
Types of Tissue Culture
The eight most common types of tissue culture are highlighted in the following points.
Seed Culture
Seeds can be cultured in vitro to produce seedlings or plants. It is the most effective method for raising the sterile seedling. The seed culture is performed to obtain various types of explants from aseptically grown plants, which aid in the maintenance of aseptic tissue.
Embryo Culture
Embryo developed from wide hybridisation between two different species may not mature fully due to embryo-endosperm incompatibility. So, the isolation and culture of hybrid embryos prior to abortion help in overcoming the post-zygotic barrier and production of interspecific or inter-generic hybrids.
Because of embryo-endosperm incompatibility, embryos developed from wide hybridisation between two different species may not mature fully. As a result, isolating and culture hybrid embryos prior to abortion aids in breaking down the post-zygotic barrier and producing interspecific or inter-generic hybrids.
Meristem Culture
To obtain disease-free plants, the apical meristem of shoots of angiosperms and gymnosperms can be cultured. Meristem tips with diameters of 0.2-0.5 mm are most frequently used to produce virus-free plants, and this technique is known as meristem-tip culture.
This method is more effective with herbaceous plants than with woody plants. In the case of woody plants, success is achieved when the explant is taken after the dormancy period has ended. After the shoot tips have multiplied, the rooting process is completed, and the rooted plantlet is potted.
Bud Culture
Buds have quiescent or active meristems in the leaf axils that can develop into a shoot. Single node culture, in which each node of the stem is cut and allowed to grow on nutrient media to develop the shoot tip from the axil, which eventually develops into a new plantlet. In the axillary bud method, axillary buds are isolated from the leaf axils and develop into shoot tips in the presence of a high cytokinin concentration.
Callus Culture
Callus is a more or less unorganised dedifferentiated mass of cells that forms in vitro from any type of explant. Callus cells are parenchymatous in nature, but they may or may not be a homogeneous mass of cells. They are meristematic tissue, and under certain conditions, they can be reorganised into shoot primordia or develop into somatic embryos.
The structure and growth habit of callus tissue from different plant species may differ. The callus growth is also affected by factors such as the type of explant and the growth conditions. After callus induction, it can be subcultured on a regular basis with an appropriate new medium for growth and maintenance.
Cell Suspension Culture
Cell suspension culture refers to the growth of individual cells obtained from any type of explant tissue or callus. These are started by placing pieces of tissue explant/callus in liquid medium (without agar) and shaking them on a gyratory shaker to provide aeration and cell dispersion. Cells are subcultured into new mediums in the same way that callus culture is.
Cell suspension cultures can be performed in a batch or continuous culture system. In the later system, the culture is continuously supplied with nutrients by the inflow of fresh medium, with subsequent draining of used medium, but the culture volume remains constant. This culture method is primarily used for metabolite synthesis or biomass production.
Anther Culture
The haploid production by another culture or pollen culture, which was first established in Datura by Guha and Maheswari (1964, 1966), is an important aspect of plant tissue culture.
Much progress has been made in various crops such as rice, wheat, maize, mustard, pepper, and others over the last few decades. The anthers containing the uni-nucleate microspores are chosen and grown in medium to produce callus from the pollen mass.
The triggering of these androgenic calli is then directed to produce embryos, from which haploid plants are developed. Anther culture can be performed on solid medium with isolated anthers, where the anther wall will break open and the androgenic calli will form from the pollen.
Microspores of the uninucleate stage are collected in liquid media and grown in suspension culture in pollen culture. The uni-nucleate pollens in suspension can give rise to calli mass or globular mass, from which plants can be raised via embryogenic or organogenic pathways.
Protoplast Culture
It is the cultivation of plant protoplasts, or the cultivation of cells devoid of a cell wall. Isolated protoplasts are typically cultured in agar media plates that are either liquid or semisolid. Enzymatic isolation of protoplasts from soft parenchymatous tissue is followed by purification and culture of viable protoplasts.
The protoplast culture is primarily used to create genetically modified plants in which the transgene is successfully inserted into the plant protoplast and the transgenic plant is regenerated from that transformed protoplast. Somatic hybridization of two plant species via protoplast fusion is another aspect of protoplast culture.
Conclusion
Wilhelm Roux, a German zoologist, made an early attempt at tissue culture in 1885, cultivating tissue from a chick embryo in a warm salt solution. However, the first real breakthrough occurred in 1907, when American zoologist Ross G. Harrison demonstrated the growth of frog nerve cell processes in a medium of clotted lymph. Tissue culture is the biological research method in which fragments of tissue from an animal or the plant are transferred to an artificial environment where they can survive and function. Seeds can be cultured in vitro to produce seedlings or plants. It is the most effective method for raising the sterile seedling. Embryo developed from wide hybridisation between two different species may not mature fully due to embryo-endosperm incompatibility. . In the case of woody plants, success is achieved when the explant is taken after the dormancy period has ended. Cell suspension cultures can be performed in a batch or continuous culture system. In the later system, the culture is continuously supplied with nutrients by the inflow of fresh medium, with subsequent draining of used medium, but the culture volume remains constant. Microspores of the uni-nucleate stage are collected in liquid media and grown in suspension culture in pollen culture.