Microparticle bombardment as a tool in plant science and agricultural biotechnology.

Microparticle bombardment technology has evolved as a method for delivering exogenous nucleic acids into plant cells and is a commonly employed technique in plant science. Desired genetic material is precipitated onto micron-sized metal particles and placed within one of a variety of devices designed to accelerate these "microcarriers" to velocities required to penetrate the plant cell wall. In this manner, transgenes can be delivered into the cell's genome or plastome. Since the late 1980s microparticle bombardment has become a powerful tool for the study of gene expression and production of stably transformed tissues and whole transgenic plants for experimental purposes and agricultural applications. This paper reviews development and application of the technology, including the protocols and mechanical systems employed as delivery systems, and the types of plant cells and culture systems employed to generate effective "targets" for receiving the incoming genetic material. Current understanding of how the exogenous DNA becomes integrated into the plant's native genetic background are assessed as are methods for improving the efficiency of this process. Pros and cons of particle bombardment technologies compared to alternative direct gene transfer methods and Agrobacterium based transformation systems are discussed.