Economic Uses of Salt-Tolerant Plants.

Climate change is likely to affect the ability of world agricultural systems to provide food, fibre, and fuel for the growing world population, especially since the area of salinised land will increase. However, as few species of plants (less than 1% of all plant species) can tolerate saline soils, we believe it is important to evaluate their potential as crops for salinised soils. We have analysed the economic and potential economic uses of plants that are listed in the database eHALOPH, including the most tolerant species, halophytes.

Potential use of saline resources for biofuel production using halophytes and marine algae: prospects and pitfalls.

There exists a global challenge of feeding the growing human population of the world and supplying its energy needs without exhausting global resources. This challenge includes the competition for biomass between food and fuel production. The aim of this paper is to review to what extent the biomass of plants growing under hostile conditions and on marginal lands could ease that competition.

Salt tolerance in rice: seedling and reproductive stage QTL mapping come of age.

Reproductive stage salinity tolerance is most critical for rice as it determines the yield under stress. Few studies have been undertaken for this trait as phenotyping was cumbersome, but new methodology outlined in this review seeks to redress this deficiency. Sixty-three meta-QTLs, the most important genomic regions to target for enhancing salinity tolerance, are reported.

ZxNHX1 indirectly participates in controlling K homeostasis in the xerophyte Zygophyllum xanthoxylum.

The succulent xerophyte Zygophyllum xanthoxylum (Bunge) Engl. can absorb Na+ from the soil as an osmoticum in order to resist osmotic stress. The tonoplast Na+/H+ antiporter ZxNHX1 is essential for maintaining the salt-accumulation characteristics of Z.

Improving crop salt tolerance using transgenic approaches: An update and physiological analysis.

Salinization of land is likely to increase due to climate change with impact on agricultural production. Since most species used as crops are sensitive to salinity, improvement of salt tolerance is needed to maintain global food production. This review summarises successes and failures of transgenic approaches in improving salt tolerance in crop species.

Secretory structures in plants: Lessons from the Plumbaginaceae on their origin, evolution and roles in stress tolerance.

The Plumbaginaceae (non-core Caryophyllales) is a family well known for species adapted to a wide range of arid and saline habitats. Of its salt-tolerant species, at least 45 are in the genus Limonium; two in each of Aegialitis, Limoniastrum and Myriolimon, and one each in Psylliostachys, Armeria, Ceratostigma, Goniolimon and Plumbago. All the halophytic members of the family have salt glands and salt glands are also common in the closely related Tamaricaceae and Frankeniaceae.

Could vesicular transport of Na+ and Cl- be a feature of salt tolerance in halophytes?

Background: Halophytes tolerate external salt concentrations of 200 mm and more, accumulating salt concentrations of 500 mm and more in their shoots; some, recretohalophytes, excrete salt through glands on their leaves. Ions are accumulated in central vacuoles, but the pathway taken by these ions from the outside of the roots to the vacuoles inside the cells is poorly understood. Do the ions cross membranes through ion channels and transporters or move in vesicles, or both? Vesicular transport from the plasma membrane to the vacuole would explain how halophytes avoid the toxicity of high salt concentrations on metabolism.

Metabolic and physiological adjustment of Suaeda maritima to combined salinity and hypoxia.

Background And Aims: Suaeda maritima is a halophyte commonly found on coastal wetlands in the intertidal zone. Due to its habitat S. maritima has evolved tolerance to high salt concentrations and hypoxic conditions in the soil caused by periodic flooding.

Tissue tolerance: an essential but elusive trait for salt-tolerant crops.

For a plant to persist in saline soil, osmotic adjustment of all plant cells is essential. The more salt-tolerant species accumulate Na+ and Cl- to concentrations in leaves and roots that are similar to the external solution, thus allowing energy-efficient osmotic adjustment. Adverse effects of Na+ and Cl- on metabolism must be avoided, resulting in a situation known as 'tissue tolerance'.

eHALOPH a Database of Salt-Tolerant Plants: Helping put Halophytes to Work.

eHALOPH (http://www.sussex.ac.

Plant salt tolerance: adaptations in halophytes.

Background: Most of the water on Earth is seawater, each kilogram of which contains about 35 g of salts, 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.

Scope: 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.

Introduction to the Special Issue: Halophytes in a changing world.

Climate change will bring about rising sea levels and increasing drought, both of which will contribute to increasing salinization in many regions of the world. There will be consequent effects on our crops, which cannot withstand significant salinization. This Special Issue looks at the roles that can be played by halophytes, extremophiles that do tolerate salinities toxic to most plants.

Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes.

Background: Halophytes are the flora of saline soils. They adjust osmotically to soil salinity by accumulating ions and sequestering the vast majority of these (generally Na(+) and Cl(-)) in vacuoles, while in the cytoplasm organic solutes are accumulated to prevent adverse effects on metabolism. At high salinities, however, growth is inhibited.

Silicon decreases chloride transport in rice (Oryza sativa L.) in saline conditions.

Silicon can alleviate salt damage to plants, although the mechanism(s) still remains to be elucidated. In this paper, we report the effect of silicon on chloride transport in rice (Oryza sativa L.) seedlings in saline conditions.

High phenotypic plasticity of Suaeda maritima observed under hypoxic conditions in relation to its physiological basis.

Background And Aims: Phenotypic plasticity, the potential of specific traits of a genotype to respond to different environmental conditions, is an important adaptive mechanism for minimizing potentially adverse effects of environmental fluctuations in space and time. Suaeda maritima shows morphologically different forms on high and low areas of the same salt marsh. Our aims were to examine whether these phenotypic differences occurred as a result of plastic responses to the environment.

A new screening technique for salinity resistance in rice (Oryza sativa L.) seedlings using bypass flow.

A lack of screening techniques delays progress in research on salinity resistance in rice. In this study, we report our test of the hypothesis that an apoplastic pathway (the so-called bypass flow) causes a difference in salt resistance between rice genotypes and can be used in screening for salinity resistance. Fourteen-day-old seedlings of low- and high-Na(+) -transporting recombinant inbred lines (10 of each) of rice IR55178 were treated with 50 mm NaCl and 0.

Studies on sodium bypass flow in lateral rootless mutants lrt1 and lrt2, and crown rootless mutant crl1 of rice (Oryza sativa L.).

An apoplastic pathway, the so-called bypass flow, is important for Na+ uptake in rice (Oryza sativa L.) under saline conditions; however, the precise site of entry is not yet known. We report the results of our test of the hypothesis that bypass flow of Na+ in rice occurs at the site where lateral roots emerge from the main roots.

The role of lateral roots in bypass flow in rice (Oryza sativa L.).

Although an apoplastic pathway (the so-called bypass flow) is implicated in the uptake of Na(+) by rice growing in saline conditions, the point of entry of this flow into roots remains to be elucidated. We investigated the role of lateral roots in bypass flow using the tracer trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) and the rice cv. IR36.

Salt sensitivity in chickpea.

The growth of chickpea (Cicer arietinum L.) is very sensitive to salinity, with the most susceptible genotypes dying in just 25 mm NaCl and resistant genotypes unlikely to survive 100 mm NaCl in hydroponics; germination is more tolerant with some genotypes tolerating 320 mm NaCl. When growing in a saline medium, Cl(-), which is secreted from glandular hairs on leaves, stems and pods, is present in higher concentrations in shoots than Na(+).

Puccinellia tenuiflora maintains a low Na+ level under salinity by limiting unidirectional Na+ influx resulting in a high selectivity for K+ over Na+.

Puccinellia tenuiflora is a useful monocotyledonous halophyte that might be used for improving salt tolerance of cereals. This current work has shown that P. tenuiflora has stronger selectivity for K+ over Na+ allowing it to maintain significantly lower tissue Na+ and higher K+ concentration than that of wheat under short- or long-term NaCl treatments.

Salinity tolerance in halophytes.

Halophytes, plants that survive to reproduce in environments where the salt concentration is around 200 mm NaCl or more, constitute about 1% of the world's flora. Some halophytes show optimal growth in saline conditions; others grow optimally in the absence of salt. However, the tolerance of all halophytes to salinity relies on controlled uptake and compartmentalization of Na+, K+ and Cl- and the synthesis of organic 'compatible' solutes, even where salt glands are operative.