Plant Genome III Conference Plant Genome III Conference
Gene transfer into important agronomic species is now becoming a reality. Following the development of direct DNA transfer methods over the past several years, transgenic plants from many cultivated species can be recovered at high frequencies, often in a variety- independent fashion. Thus, constraints previously imposed by biological gene transfer systems, either in terms of vectors or cellular parameters influencing regeneration from dedifferentiated tissue, no longer limit the range of species that can be engineered. The majority of gene transfer experiments have focused, up to now on maximizing efficiencies for the recovery of stably transformed plants, and also extending the range of genotypes that could be engineered using a specific procedure. Thus, an increasing number of transgenic legumes, cereals, woody species, tubers, vegetables and ornamentals are added continuously to the list of species that are considered no longer to be recalcitrant. However, in order for all this research to be useful in the context of plant genome research a number of new areas need to be targeted. These include the ability to recover numerous plants containing not only marker genes but also genes of interest that perform a useful function. The ability to engineer plants with multiple genes is also of extreme importance, if we are to target successfully more complex agronomic traits. We need to develop a comprehensive understanding of the molecular biology/biochemistry of transgenic plants engineered with complex and multigene vectors. Strategies to accomplish this, must include programs to understand factors responsible for controlling gene expression and regulation of transgenes and also the stability of such traits over many generations, particularly in the field. Gene(s) size, copy number and co-expression of multiple transgenes in plants are parameters that need to be studied further. Examples of preliminary experiments utilizing rice as a model system for cereal genome research will be given to illustrate the significance of such research.