Production of the Marker free transgenic plants – An update Review

Abstract

Selectable marker genes are pivotal for the development of plant transformation technologies because marker genes allow researchers to identify or isolate the cells that are expressing the cloned DNA, to monitor and select the transformed progeny. As only a very small portion of cells are transformed in most experiments, the chances of recovering transgenic lines without selection are usually low. Since the selectable marker gene is expected to function in a range of cell types it is usually constructed as a chimeric gene using regulatory sequences that ensure constitutive expression throughout the plant. Transgenic crop or plants are very decisive for the growing population to maintain their necessary food, medicine, protect the environment and other things. But the transgenic crop or plants have some risk or controversy in human health, agriculture, and environment. Selectable marker genes are widely used for the efficient transformation of crop plants. In most cases, selection is based on antibiotic or herbicide resistance due mainly to consumer concerns, a suite of strategies (site-specific recombination, homologous recombination, transposition and co-transformation) have been developed to eliminate the marker gene from the nuclear or chloroplast genome after selection. Recently, scientists are producing several transgenic plants without selectable marker gene. This review article describes the developments made in the recent past on plant transformation systems using different selection methods adding a note on their importance as marker genes in transgenic crop plants.