Biolistic maize transformation: Improving and simplifying the protocol efficiency

Two decades have passed since the first maize transformation protocol. Genetic breeding has been decisive and essential to transform maize a major food crop worldwide. Biotechnology plays an important role in plant genetic breeding, particularly for the introduction of novel traits in order to improve agronomic performance, medical and industrial applications and food quality. In recent years, the development of efficient plant regeneration systems in cereal crops and the field of biotechnology have opened up new opportunities for genetic transformation of crop plants. Some monocot plants were initially considered difficult for genetic engineering, primarily due to their recalcitrance to in vitro regeneration and their resistance to Agrobacterium. Continuous efforts and studies of different tissues for regeneration potential, development of various DNA delivery methods, and optimization of gene expression cassettes have led to the development of reliable transformation protocols for major cereals, including maize. Consequently, this research group has focused its attention on maize transformation mediated by microprojectile bombardment as a device of DNA delivery into maize cells. This method offers a rapid and simple way of introgression of candidate genes into cells. However, there are some points that still need to be studied and improved in order to achieve appropriate transformation efficiency to optimize the processing conditions to obtain fertile plants.