Genomic information and genetic resources have led to a substantial increase in our knowledge about how plants respond to stressful environmental conditions. This provides the basis for many new strategies for optimization of stress tolerance in crop plants through both traditional and transgenic approaches. Application of novel stress-tolerance technologies will require extensive physiological and agronomic evaluation of plants that express these genes to determine their ultimate applicability to crop systems. Preliminary work with transgenic cotton plants show that optimization of expression patterns using different promoters or other regulatory strategies will be necessary.