Question

Somaclonal variations appear in
(a)Organism produced through somatic hybridization
(b)Plants growing in highly polluted conditions
(c)Apomictic plants
(d)Tissue cultured plants

Answer 1

Hint: The variation of somaclonal is the variation seen in plants created by the culture of plant tissue. A major cause of this variance is chromosomal rearrangements. Affected characters have both qualitative and quantitative attributes.

Complete answer:
-Somaclonal variation is not restricted to but is especially prevalent in, callus-regenerated plants in tissue culture.
-The differences can be genotypic or phenotypic, which may be either of genetic or epigenetic origin in the latter case.
-If no visual or morphogenetic changes are evident, it is appropriate to apply other plant screening procedures. Somaclonal variance has both benefits and disadvantages. Somaclonal variation has been called the phenomenon of high variability in individuals from plant cell cultures or adventitious shoots.

Additional Information:
 -In operations requiring clonal uniformity, a significant drawback of somaclonal heterogeneity exists, as in the horticulture and forestry industries, where tissue culture is used to rapidly spread elite genotypes.
-The random and genetically unstable variants are selected.
-Not suited to complex agronomic characteristics such as yield, efficiency, etc.
-Variants that have pleiotropic effects can evolve.
-Plant/crop enhancement is the significant possible gain of somaclonal variation. Somaclonal variation contributes to extra genetic diversity being produced.
-Resistance to disease patho toxins, herbicides, high salt concentrations, mineral toxicity, and resistance to environmental or chemical stress, as well as increased development of secondary metabolites are characteristics for which somaclonal mutants can be enriched during in vitro cultivation.
-Suitable for new-species breeding.
So, the correct answer is ‘Tissue cultured plants’.

Note: -Changes in chromosome numbers (polyploidy and aneuploidy), chromosome arrangement (translocations, deletions, insertions, and duplications), and DNA sequence (base mutations) are common genetic alterations which cause somaclonal variation. A common event associated with epigenetics will be gene methylation.