Research progress of marker-free transgenic plants

Selectable marker genes have been extraordinarily useful in genetic transformation of plants.Currently,the most frequently used selectable marker genes are antibiotic or herbicide resistance genes,which are being increasingly concerned on the safety issues of transgenic plants.In this paper,methods and applications for the cultivation of marker-free transgenic plants were reviewed,including co-transformation,site-specific recombination,transposable system,homologous recombination and multi-auto transformation system.The pros and cons of these approaches were also discussed with a view to promote the industrialization process of transgenic plants.