Reasons and riddance of Agrobacterium tumefaciens overgrowth in plant transformation

Agrobacterium tumefaciens-mediated plant transformation has become routine work across the world to study gene function and the production of genetically modified plants. However, several issues hamper the transformation process in a profound way, both directly and indirectly. One of the major concerns is the overgrowth of Agrobacterium, which occasionally appears after the co-cultivation phase of the explant. This phenomenon is reported in several species and seems to spoil the whole transformation process. There are multiple approaches being employed to counter this unwanted growth of bacteria in a few plant species. In reality, once the overgrowth appears, it becomes nearly impossible to cure it. Hence, for the prevention of this phenomenon, numerous factors are regulated. These factors are: explant nature, A. tumefaciens strain, T-DNA vector, co-cultivation (time and condition), acetosyringone, washing medium, antibiotics (type, concentration, combination, incubation period), etc. In this article, we discuss these factors based on available reports. It can be of immense help in formulating viable strategies to control A. tumefaciens overgrowth.