Recent developments in generation of marker-free transgenic plants

A plant modified through artificial insertion of a foreign DNA into its genome is referred to as “genetically modified plant” or a “transgenic” plant. The selection of the transgenic tissues during the genetic transformation process is based on the constitutively expressed marker gene(s) coding for reporters, such as those conferring resistance against antibiotics and/or herbicides. In this direction, Agrobacterium-mediated genetic co-transformation is arguably the most commonly used technique to transfer the gene(s) of interest as well as the marker gene(s). However, the latter is purposeless once a transgenic tissue has been selected. Although these marker genes are important for screening purposes, they exhibit safety concerns for the environment as well as among consumers. At times, commercial transgenic plants transfer these gene(s) to the weeds or other organisms, leading to the development of resistance among nontarget plants. Moreover, the escape of such gene could affect the wild relatives or land races via gene flow. Therefore, in order to maintain sustainability, removing the marker gene(s) from a transgenic crop is of utmost importance, prior to its commercialization. Hitherto, several methodologies have been evolved for the development of a marker-free transgenic crop. In the present summary, we discuss the merits and the shortcomings of the Agrobacterium-mediated genetic co-transformation. In addition, we review the recent developments among other approaches and their impacts and suggest directions for their maximum utilization in the near future.