Recent advances in engineering plant tolerance to abiotic stress: achievements and limitations.

Abiotic stresses, especially salinity and drought, are the primary causes of crop loss worldwide. Plant adaptation to environmental stresses is dependent upon the activation of cascades of molecular networks involved in stress perception, signal transduction, and the expression of specific stress-related genes and metabolites. Consequently, engineering genes that protect and maintain the function and structure of cellular components can enhance tolerance to stress. Our limited knowledge of stress-associated metabolism remains a major gap in our understanding; therefore, comprehensive profiling of stress-associated metabolites is most relevant to the successful molecular breeding of stress-tolerant crop plants. Unraveling additional stress-associated gene resources, from both crop plants and highly salt- and drought-tolerant model plants, will enable future molecular dissection of salt-tolerance mechanisms in important crop plants.