Question

Somaclonal variation can be obtained by
(a) Application of colchicines
(b) Irradiation with gamma- rays
(c) Tissue culture
(d) Hybridisation

Answer 1

Hint: This is a method of biological research in which fragments of tissue from an animal or plant or transferred to an artificial environment where they can continue to survive and function.

Complete answer:
Somaclonal variation can be obtained by tissue culture. Differences between individuals within the species are known as variation. The variations that are observed in tissue culture raised plants somatic cells are termed as a somaclonal variation. It is induced by growing cell suspension cultures for several cycles to produce a large number of plants. This production of large numbers of plants is followed by screening for desirable traits in the regenerated plants and their progeny.

Additional Information: -Somaclonal variation term was first coined by Larkin and Scowcroft in 1981.
-According to Scowcroft genetic variation occurring in tissue culture regenerated plants through somatic tissues is commonly referred to as a somaclonal variation.
-It is mainly used to produce clones of a plant. The technique of plant tissue culture is highly used for commercial production of plants used for potting, landscape development, and florist subjects, which uses meristem and shoot culture to produce large numbers of identical individuals.
-To conserve rare or endangered plant species. It is also used for embryo rescue.
- Application of colchicines: Either in mitosis or meiosis colchicines disrupt the normal sequence of a nuclear division and induce somatic doubling by inhibiting microtubule formation which in turn prevents the spindle formation. This ultimately prevents the chromosomes from moving apart during cell division. This results in a cell with a doubled chromosome number.
 -Irradiation with gamma- rays: γ-rays are ionizing radiations that serve as a chronic source of radiation that traverses deep in tissues and hence is used for the induction of mutations in crop plants.
 -Hybridisation: The crossing of two pure-breeding varieties to produce a new composition of genes in the progeny is hybridization. It produces a new composition of already existing genetic material or genes but does not introduce a new allele or remove an existing allele from the population gene pool.
So, the correct answer is,’ Tissue culture’.

Note: -Somaclonal variation term was first coined by Larkin and Scowcroft in 1981.
- The definition of somaclonal variation given by Scowcroft is “genetic variation occurring in tissue culture regenerated plants through somatic tissues is commonly referred to as a somaclonal variation”.
-Embryo Rescue is the process to cross-pollinate distantly related species and then they are tissue cultured, the resulting embryo will be grown into a new plant that would otherwise normally die.