Abstract
Drought and soil salinity are at present the major factors responsible for the global reduction of crop yields, and the problem
will become more severe in the coming decades because of climate change effects. The most promising strategy to achieve the
increased agricultural production that will be required to meet food demands worldwide will be based on the enhancement
of crop stress tolerance, by both, traditional breeding and genetic engineering. This, in turn, requires a deep understanding of
the mechanisms of tolerance which, although based on a conserved set of basic responses, vary widely among plant species.
Therefore, the use of different plant models to investigate these mechanisms appears to be a sensible approach. The genus
Portulaca could be a suitable model to carry out these studies, as some of its taxa have been described as tolerant to drought
and/or salinity. Information on relevant mechanisms of tolerance to salt and water stress can be obtained by correlating the
activation of specific defence pathways with the relative stress resistance of the investigated species. Also, species of the genus
could be economically attractive as `new¿ crops for `saline¿ and `arid¿, sustainable agriculture, as medicinal plants, highly nutritious vegetable crops and ornamentals.
