Agrobacterium and Plant Biotechnology

Agrobacterium-mediated transformation has revolutionized agriculture as well as basic research in plant molecular biology, by enabling the genetic modification of a wide variety of plant species. Advances in binary vector design and selection strategies, coupled with improvements in regeneration technology and gene delivery mechanisms, have dramatically extended the range of organisms, including grains, that can be transformed. Recent innovations have focused on methods to stack multiple transgenes, to eliminate vector backbone sequences, and to target transgene insertion to specific sites within the host genome. Public unease with the presence of foreign DNA sequences in crop plants has driven the development of completely marker-free transformation technology and molecular strategies for transgene containment. Among the many useful compounds produced in genetically modified plants are biodegradable plastics, primary and secondary metabolites with pharmaceutical properties, and edible vaccines. Crop plant productivity may be improved by introducing genes that enhance soil nutrient utilization or resistance to viral, bacterial, or fungal diseases. Other transgenes have been shown to confer increased tolerance to many of the environmental constraints, including drought, extreme temperature, high salinity, and heavy metal soil contamination, faced by resource-poor farmers attempting to cultivate marginally arable land. Early applications of plant biotechnology focused primarily on traits that benefit farmers in industrialized regions of the world, but recent surveys document the degree to which this pattern is changing in favor of modified crops that contribute to enhanced ecological and human health. Documented decreases in the use of pesticides attributable to genetically engineered plants are harbingers of the health and environmental benefits that can be expected from transgenic crop plants designed to decrease reliance on harmful agrochemicals. As one thread in a network that also includes integrated pest and soil fertility management, a reduced emphasis on monoculture, and traditional crop breeding, plant genetic modification has the potential to help those who currently suffer from inadequate access to a full complement of nutrients. The development of “golden rice” illustrates the possibility to imbue a plant with enhanced nutritional value, but also the challenges posed by intellectual property considerations and the need to introduce novel traits into locally adapted varieties. Implementation of plant genetic modification within a framework of sustainable agricultural development will require increased attention to potential ecological impacts and technology-transcending socioeconomic ramifications. Successful technology transfer initiatives frequently involve collaborations between scientists in developing and industrialized nations; several non-profit agencies have evolved to facilitate formation of these partnerships. Capacity building is a core tenet of many such programs, and new paradigms for incorporation of indigenous knowledge at all stages of decision-making are under development. The complex (and sometimes controversial) social and scientific issues associated with the technology notwithstanding, Agrobacterium-mediated enhancement of agronomic traits provides novel approaches to address commercial, environmental, and humanitarian goals.