Most of the water on Earth is seawater, each kiolgram of which contains about 35 g of salt, and yet most plants cannot grow in this solution; less than 0.2 % of species can develop and reproduce with repeated exposure to seawater. These ‘extremophiles’ are called halophytes.
Improved knowledge of halophytes is of importance to understanding our natural world and to enable the use of some of these fascinating plants in land re-vegetation, as forages for livestock, and to develop salt-tolerant crops. Annals of Botany has recently published a Special Issue on Halophytes and Saline Adaptations, in which the evolution of salt tolerance in halophytes, their life-history traits and progress in understanding the molecular, biochemical and physiological mechanisms contributing to salt tolerance are summarized in 16 papers by leading researchers in the subject. In particular, cellular processes that underpin the ability of halophytes to tolerate high tissue concentrations of Na+ and Cl–, including regulation of membrane transport, their ability to synthesize compatible solutes and to deal with reactive oxygen species, are highlighted. Interacting stress factors in addition to salinity, such as heavy metals and flooding, are also topics gaining increased attention in the search to understand the biology of halophytes, and are addressed in this Special Issue.