Transgenic plants for abiotic stress tolerance: current status

Abstract

Abiotic stress is one of the primary causes of crop losses worldwide (Bray et al. 2000. Responses to abiotic stresses. In: Buchanana BB, Gruissem W, Jones RL, editors. Biochemistry and Molecular Biology of Plants. Rockville (MD): American Society of Plant Physiologists. p. 1158–1249). To cope with the detrimental effects of stress, plants have evolved many biochemical and molecular mechanisms. One of the well-documented stress responses in plants is accumulation of osmolytes during stress. Although their actual roles in plant-stress tolerance remain controversial, these molecules are thought to have positive effects on enzyme and membrane integrity, along with adaptive roles in mediating osmotic adjustment in plants grown under drought conditions. Recent studies have demonstrated that the manipulation of genes involved in the biosynthesis of these osmolytes have improved plant tolerance to drought and salinity in a number of crops. There is renewed hope of understanding the molecular basis of osmolyte accumulation under stress and manipulating these processes via genetic engineering. For future work on generating transgenic plants with still higher levels of tolerance, the new knowledge may be used via guided genetic engineering of multiple genes to create crop plants with significantly increased productivity under drought stress. This review surveys the current advances in engineering abiotic stress-tolerant plants, particularly the genetic engineering of osmolyte genes (osmoprotectants) for imparting drought stress tolerance in plants.