Micropropagation

Micropropagation is the artificial method of growing plants through tissue or cell culture techniques. It is also called tissue culture. Asexual means of reproduction is used to produce plants called vegetative propagation.

There are four stages involved in this process. 

• Stage 1 is culture initiation and establishment

• Stage 2 is shoots multiplication 

• Stage 3 is methods involved 

• Stage 4 is rooting the shoots

It is used to multiply a wide variety of plants, especially those genetically modified. It is also used in plants that do not respond well to vegetative reproduction or where it is the cheaper method of propagating.

Micropropagation 

Micropropagation was developed in the 1950s-60s. Micropropagation is a promising method to grow medicinally important plants faster and on a large scale. The basic principle of micropropagation is to grow large scale plants under the right conditions and with proper nurture and care. There are multiple ways of achieving micropropagation, such as enhanced axillary shoot development, de novo adventitious shoot formation, and somatic embryogenesis. Tiny amounts of plant tissue are sufficient for generating millions of clones in a year using micropropagation. If done in the standard method of producing it, it would take several years to do so.

Classification of micropropagation 

Micropropagation in plants can be classified based on the part of the plant in which they are present or the kind of cells they contain.

There are two main micropropagation methods, and they are: 

• Meristematic

• Permanent 

Meristematic tissue 

Plants grow only in certain areas. The dividing tissue, also called meristematic tissue, is located only in these areas. Contingent upon the space where they are available, meristematic tissues are delegated apical, parallel, and inter collar. 

• Apical meristem
  It is available on the developing closures of stems and roots and builds the length of stems and roots. 

• Lateral meristem (Cambium)
  It is responsible for increasing the circumference of the stem or root.

• Intercalary meristem
  It is seen in some plants and is located near the node. The new cells produced by the meristem are initially similar to the meristem itself. When they grow tall, all their properties start changing, and they show differences as components of other tissue.

Permanent tissue

They are made up of cells that do not pass through cell division and form permanent tissue. This course of taking a super durable shape, size, and capacity is called separation. Once they lose the ability to divide, they are derived from meristematic tissue. They are classified as simple (parenchyma, collenchyma, and sclerenchyma) and complex (xylem and phloem) tissues.

Simple permanent tissue

Simple permanent tissues are all the same. They have a standard function, origin, and structure. They are classified as a single cell type.

• Parenchyma
  These polygonal cells are living and feature a sizable central vacuole and intercellular gaps. Pith and ground tissue are created by parenchymatous cells. Chlorenchyma is a kind of parenchyma that contains chloroplasts. The chlorenchyma aids photosynthesis. 

Aerenchyma is a kind of parenchyma that has significant air gaps. The aerenchyma’s primary function is to provide buoyancy. In vegetables and fruits, specific parenchymatous cells serve as starch storage chambers.

• Collenchyma
  These are live cells stretched out and have minute intercellular gaps. Cellulose and pectin make up their cell walls. Collenchyma is present on the margins of stems and leaves, and it provides plants with structural flexibility and mechanical support.

• Sclerenchyma

These tissues are stiff and lifeless and are typically found in the coverings of nuts and seeds. Between the cells, there is no gap. Because the cells have very thick walls, they are stiffer, and their rigidity gives the plant its strength.

Complex permanent tissue

The complex tissues are crucial since they are in charge of the plant’s transportation system. It consists of phloem and xylem. They make it easier for water, food, and nutrients to move around the plant.

• Xylem

This tissue is responsible for transporting liquid materials throughout the plant. The transit begins from the root and continues until each leaf is reached. It provides lignin-based components to sustain the plant. Vessels, tracheids, xylem parenchyma, and xylem fibres make up the xylem.

• Phloem
  This tissue aids in the movement of food throughout the plant. The companion cells, phloem fibres, phloem parenchyma and the sieve tubes are some of the phloem’s key components.

Methods of micropropagation

There are five methods of micropropagation:

• Meristem culture 

In this method of micropropagation, meristematic tissues are used for culturing purposes. These tissues can divide quickly to grow and hence, are also known as dividing tissue. They contribute to the vegetation’s growth significantly. These cells take care of a plant’s growth in length and diameter. 

• Callus culture

The callus development is incited by putting a piece of tissue in a development culture media under good circumstances. After that, the callus is shifted to a newer media with high auxin or auxin and cytokinin (plant development controllers) groupings for organ advancement.

• Suspension culture

The suspension culture strategy includes the suspension arrangement by increasing single cells or totals when unsettled in circulated air through a clean fluid medium. The two sorts of suspension cultures incorporate batch culture and continuous culture.

• Embryo culture

Embryo culture is the detachment of immature or mature embryos cultured in an appropriate development medium.

• Protoplast culture

Protoplast is a round, bare, living cell without a cell divider. This is achieved by stripping the cell mass of plants by utilising synthetic, mechanical, or enzymatic cycles. Protoplast culture is the segregation of plant cells, followed by debasement of cell dividers and refined in a fluid media under reasonable physiological circumstances.

Conclusion

Due to heavy demand and multiple uses, these crops using micropropagation are grown widely in large parts of land worldwide. Micropropagation is also famous for the commercial production of a few plants, such as sugarcane, due to the significant demand for sugar. Generally, this method is not used to produce horticultural crops because of the seedless method. However, it is still being used to produce other vital crops. This requires less investment of plants, and a little goes a long way.

Space is not an issue in micropropagation because, in the initial and developmental stages of preparation, a very tiny amount of tissue is required to produce and develop a culture. Once it develops and is ready to be transplanted to the greenhouse and later to farms and lands, it takes up space due to the multiplied samples. 

Micropropagation also has its disadvantages. One of the most significant disadvantages of this process is that it is time-consuming. This requires instruments and tools to be sterilised and the tissue sample to be well sterilised.