Molecular Markers for Genetic Fidelity Assay of Tissue Cultured Crops

Tissue culture techniques are being widely used for the production of large-scale disease-free planting material aseptically on artificial media within a lesser span of time and space. This technique has gained tremendous popularity in recent days for the commercial production of several clonally propagated plants such as banana, bamboo, pointed guard, seed potato, strawberry, pineapple, papaya etc. Even in seed-grown plants, this technology has application in overcoming the barriers like dormancy, sexual compatibility, germination etc. But the major drawback of tissue culture raised plantlets is that they show somaclonal variation, i.e. alteration in the genetic constitution of the plant leading to the disappearance of true-to-type nature and resulting variants may not be desirable. In such case, the genetic fidelity test is mandatory to confirm the true-to-type genetic makeup of newly derived plantlets. Several strategies have been used to ascertain the genetic fidelity of the in vitro raised progenies comprising morpho-physiological, biochemical and cytological approaches. These approaches are mainly based on phenotypic characters, which can be affected by the in-vitro manipulation, environment and types of plant tissue; hence it is not easy to differentiate clonal fidelity with a high probability. In contrast, for a similar purpose, the DNA- based molecular markers are versatile tools with broader applicability in various fields of applied biology. These molecular markers have the edge over aforementioned traditional non-DNA based markers concerning environmental interaction, developmental stage, tissue, time and cost. The present paper contains different techniques of genetic fidelity assay to confirm the true-to-type genetic constitution in tissue culture raised crops.