Tissue Culture-based Agrobacterium-mediated and in planta Transformation Methods

Gene transformation can be done in direct and indirect (Agrobacterium-mediated) ways. The most efficient method of gene transformation to date is the Agrobacterium-mediated method. The main problem of this method is that some plant species and mutant lines are recalcitrant to regeneration. Requirements for sterile conditions for plant regeneration are another problem of Agrobacterium-mediated transformation. The development of a genotype-independent gene transformation method is of great interest in many plants. Some Agrobacterium-mediated gene transformation methods independent of tissue culture are reported in individual plants and crops. Generally, these methods are called in planta gene transformation. In planta transformation methods are free from somaclonal variation and easier, quicker, and simpler than transformation methods based on tissue culture. Vacuum infiltration, injection of Agrobacterium culture into plant tissues, pollen-tube pathway, floral dip and floral spray are the main methods of in planta transformation. Each of these methods has its own advantages and disadvantages. Simplicity and reliability are the primary reasons for the popularity of the in planta methods. These methods are much faster than regular Agrobacterium-mediated gene transformation based on tissue culture and success can be achieved by non-experts. In the present review, we highlight all methods of in planta transformation comparing them with regular Agrobacterium-mediated transformation methods based on tissue culture. Finally, successful recent transformations using these methods are presented.