Agrobacterium-mediated transformation of cereals - from technique development to its application

Agrobacterium tumefaciens is a very useful vector to transfer foreign genes into dicotyledonous cells. Monocotyledonous, especially cereals, were considered outside the host range of the bacteria. The main, alternative technique of transformation developed for them was delivery of naked DNA (e.g. microprojectile bombardment, electroporation of protoplasts). The results of Agrobacterium-mediated transformation of cereals accumulated during the last few years confirmed that the method was reliable and repeatable also for this group of plants. The most important advantages of Agro-based system include relatively high transformation efficiency, integration of defined piece of DNA (transgene) frequently as a single copy, Mendelian transmission to the next generation, simple transformation procedure and lower cost of equipment than biolistic. Discussed are the crucial factors of successful Agrobacterium-mediated transformation of cereals: type of plant tissue used, A. tumefaciens strains and plasmids (vectors), activation of bacterial virulence system and promoter, reporter as well as selectable genes applied for transgene construction. The review contains examples of Agrobacterium-based transformation methods and practical opportunities of their application as well as the list and description of cereal transgenic plants (rice, maize, wheat and barley) obtained after Agrobacterium-mediated transformation.