Homeostasis, a set-value for metabolism under optimal conditions, is rarely achieved by plants because of the cost exerted by external stress factors: climatic, biotic, and nutrient imbalances. Among these, stresses caused by abiotic conditions, such as temperature extremes (freezing, cold and heat), water availability (drought and ion excess) and ion toxicity (salinity and heavy metals), have been difficult to dissect because defense responses to abiotic factors require regulatory changes to the activation of multiple genes and pathways. Genomics technologies that have emerged during the past decade have been useful in addressing, in an integrated fashion, the multigenicity of the plant abiotic stress response through genome sequences; cell-, organ-, tissue- and stress-specific transcript collections; transcript, protein and metabolite profiles and their dynamic changes; protein interactions; and mutant screens.