DREB takes the stress out of growing up

Ice, flood, and drought have been the scourge of agriculture over the ages, bringing with them poor harvests and the threat of famine. Today, the importance of crop resistance to water stress, extremes of salinity, and harsh temperature is likely to increase further as the range of environments in which crops are cultivated expands and the incidence of extreme weather conditions increases with the specter of global warming. In this issue, Kazuo Shinozaki and colleagues1 describe an approach for bolstering plant resistance to such environmental insults. By overexpressing a single transcription factor, they have succeeded in inducing the expression of several stress-related genes, leading to striking improvements in plant tolerance to freezing, salt loading, and dehydration (Fig. 1). Although conventional plantbreeding programs have improved yields for crops grown in stressful environments, there is a growing belief that further gains can only be achieved through targeted manipulation of genes involved in stress resistance2. Many stress-inducible genes have been identified over the past decade3, but only recently have functional roles in stress tolerance been identified. This makes it feasible to improve crop stress tolerance by targeting stressrelated genes for genetic manipulation. The work reported in this issue is an important step toward that goal. Shinozaki’s group had already identified a dehydration-responsive transcription factor (DREB1A) that mediates transcription of several genes in response to cold and water stress4. Stress-related gene expression is induced by the binding of DREB1A, which is itself induced by cold and water stress, to a cis-acting DNA (DRE) element in the promoters of genes such as rd29A, rd17, cor6.6, cor 15a, erd10, and kin1. This binding initiates synthesis of gene products implicated in plant acclimation responses to low temperature and water stress3,5. The signal transduction pathway mediating these inductive events is independent of abscisic acid (ABA), a hormone involved in expression of similar genes in response to water stress6. In the present paper, Shinozaki and colleagues have transformed Arabidopsis with