Cell and Tissue Culture for Plant Improvement

Refined tissue culture procedures have made it possible to introduce foreign DNA and cloned genes into cultured cells, protoplasts, and plant organs from diverse biological systems and to regenerate transgenic plants in more than 45 plant species with new genetic properties. In monocots, protoplast-mediated transformation and, more recently, microprojectile bombardment of cultured cells and tissues have been commonly used to produce transgenic plants. Microprojectile bombardment of cultured cells, particularly plant organs such as immature embryos and meristems, hold great promise to enhance the efficiency of genetic transformation and should be applicable to a large number of genotypes and species recalcitrant to tissue culture. There exists voluminous literature on genotypic differences of tissue culture response as measured by callus formation, somatic embryogenesis, and plant regeneration ability in several plant species. Techniques of in vitro propagation and meristem culture are commercially used in the production of virus-free germplasm and in the mass multiplication of several ornamental plants and other vegetatively propagated species.