Plant Propagation Techniques

Explant is any portion taken from a plant that will be used to initiate a culture. It can be a portion of the shoot or of the leaves or even just some cells. It is a piece of sterile plant tissue to be used for tissue culture under aseptic conditions. Inoculant is the active material used in an inoculation. Clones are organisms that are exact genetic copies. Somacloning is cloning of plant with a single cell. 

• Totipotency is the ability of a single cell to divide and produce all of the differentiated cells in an organism. 
  
• For example, Spores and zygotes are examples of totipotent cells.
• Hence a plant cell has the potential to develop into a full plant. The property is called Totipotency.
• So, the correct answer is 'Totipotency'.

F.C. Steward and his colleagues famously demonstrated cellular totipotency using carrot phloem cells in the 1950s.

Tissue culture is a biological technique which involves the development of the plant by the totipotent cells under the controlled condition on a nutrient culture medium of the known composition. The totipotent cells are taken from the active part of the plant like root, stem leaf, pollen etc. The plant part which is used for the culture is known as explant. 

Totipotency is the ability of the plant to generate new cell by cell division. A cell from leaf is made to grow into complete plant under culture conditions. The cell of the leaf used for the culture is taken from the tip of the leaf and it has ample amount of meristematic cell. The meristematic cell of the leaf is grown on a cultured media it develops into a undifferentiated mass of callus. The cells of callus have active nucleus and cytoplasm so they are totipotent. The totipotent cells of callus differentiate on treating with growth hormone. Callus when treated with auxin it promotes rooting and when it is treated with cytokinin it stimulates cell maturation, differentiation and finally, promotes the development of stem. 

An explant is any part of a plant (tissue, organ, or cell) that is excised and placed into a culture medium for tissue culture.

Axenic culture refers to a culture that is free from any other living organisms, meaning it is a pure culture.

• The process by which thousands of plants can be raised within limited time and space is Tissue culture.
  
• When new plants are grown from a small piece of plant tissue or cells removed from the growing tips of a plant in a suitable growth medium is called tissue culture.
  
• Its advantages are:-

Meristem is free from viruses and they are used to grow virus-free plant cultures. The meristem has the ability of rapid rate of mitotic cell division, which is much more than the viral rate of division. Hence, the virus is unable to spread through them, hence the meristems are almost always free of viruses.

Tissue culture is the growth of tissues or cells in an artificial medium separate from the organism. Plant parts can be sterilized by using several disinfecting agents i.e., use of chemicals.

In plant tissue culture, an explant is the initial plant tissue piece that is introduced into the culture medium. This explant will then proliferate, differentiate, and regenerate into whole plants through various tissue culture techniques like organogenesis or somatic embryogenesis.

Tissue culture is a collection of techniques used to grow cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition ( in vitro). The emergence of this technique became a turning point when polio virus, could be cultivated in vitro, a discovery of Enders, Weller, and Robbins (1949). This led to the feasibility of quantitative metabolic studies in animal viruses. Tissue culture is, therefore, today a vital part of life science research ( across plants and animals ) and in every area of research that includes bacteriology, embryology and virology.

Plant cells are totipotent. Hence, plant cells can be cultured to grow entire plants. In-plant tissue culture, a small meristematic tissue called explant is used to generate a mass of undifferentiated cells called callus. Entire plantlets can be generated from callus by applying a carefully balanced ratio of phytohormones.

Totipotency is the ability of a single cell to divide and produce all of the differentiated cells in an organism. Spores and zygotes are examples of totipotent cells. In the spectrum of cell potency, totipotency represents the cell with the greatest differentiation potential. Many somatic plant cells, including some fully differentiated types (e.g., leaf mesophyll), provided they contain intact nuclear, plastid and mitochondrial genomes, have the capacity to regenerate into whole plants. 

Somaclonal variation is the variation seen in plants that have been produced by plant tissue culture. Chromosomal rearrangements are an important source of this variation. The term somaclonal variation is a phenomenon of broad taxonomic occurrence, reported for species of different ploidy levels and for outcrossing and inbreeding, vegetatively and seed propagated and cultivated and non-cultivated plants. Characters affected include both, qualitative and quantitative traits. Somaclonal variation is seen in tissue culture grown plants.
Somaclonal variation is not restricted to, but is particularly common in, plants regenerated from callus. The variations can be genotypic or phenotypic, which in the latter case can be either genetic or epigenetic in origin.
Typical genetic alterations are: changes in chromosome numbers (polyploidy and aneuploidy), chromosome structure (translocations, deletions, insertions and duplications) and DNA sequence (base mutations). A typical epigenetics-related event would be gene methylation.