Mechanisms of salinity tolerance

Abstract

<jats:p>The physiological and molecular mechanisms of tolerance to osmotic and ionic components of salinity stress are reviewed at the cellular, organ, and whole-plant level. Plant growth responds to salinity in two phases: a rapid, osmotic phase that inhibits growth of young leaves, and a slower, ionic phase that accelerates senescence of mature leaves. Plant adaptations to salinity are of three distinct types: osmotic stress tolerance, Na<jats:sup>+</jats:sup>or Cl<jats:sup>−</jats:sup>exclusion, and the tolerance of tissue to accumulated Na<jats:sup>+</jats:sup>or Cl<jats:sup>−</jats:sup>. Our understanding of the role of the HKT gene family in Na<jats:sup>+</jats:sup>exclusion from leaves is increasing, as is the understanding of the molecular bases for many other transport processes at the cellular level. However, we have a limited molecular understanding of the overall control of Na<jats:sup>+</jats:sup>accumulation and of osmotic stress tolerance at the whole-plant level. Molecular genetics and functional genomics provide a new opportunity to synthesize molecular and physiological knowledge to improve the salinity tolerance of plants relevant to food production and environmental sustainability.</jats:p>