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Potential use of halophytes to remediate saline soils.

Hasanuzzaman M, Nahar K, Alam MM, Bhowmik PC, Hossain MA, Rahman MM, Prasad MN, Ozturk M, Fujita M - Biomed Res Int (2014)

Bottom Line: The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems.Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level.Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well.

View Article: PubMed Central - PubMed

Affiliation: Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka 1207, Bangladesh.

ABSTRACT
Salinity is one of the rising problems causing tremendous yield losses in many regions of the world especially in arid and semiarid regions. To maximize crop productivity, these areas should be brought under utilization where there are options for removing salinity or using the salt-tolerant crops. Use of salt-tolerant crops does not remove the salt and hence halophytes that have capacity to accumulate and exclude the salt can be an effective way. Methods for salt removal include agronomic practices or phytoremediation. The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems. Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level. Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well. This review focuses on the special adaptive features of halophytic plants under saline condition and the possible ways to utilize these plants to remediate salinity.

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Related in: MedlinePlus

Na+ and Cl− ions concentration in the shoot of some halophytes grown in natural habitats [3] with permission from Springer.
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fig4: Na+ and Cl− ions concentration in the shoot of some halophytes grown in natural habitats [3] with permission from Springer.

Mentions: Salinity is not inimical to all plants. The distribution, exploitation [26], and physiology of salt tolerance of halophytes are intensively studied [16, 27, 28]. Salts taken up by halophytes do not directly control plant growth by affecting turgor, photosynthesis, or the activity of one or another enzyme. The build-up of salts in old leaves hastens their death. The loss of leaves affects the supply of assimilates or hormones to the growing organs and hereby affects growth [29, 30]. Despite their polyphyletic origins, halophytes appear to have evolved the same basic method of osmotic adjustment: accumulation of inorganic salts, mainly NaCl, in the vacuole and accumulation of organic solutes in the cytoplasm. Differences between halophyte and glycophyte ion transport systems are becoming apparent. The pathways by which Na+ and Cl− enter halophyte cells are not well understood but may involve ion channels and pinocytosis in addition to Na+ and Cl− transporters. Na+ uptake into vacuoles requires Na+/H+ antiporters in the tonoplast and H+ ATPases and perhaps PPIases to provide the proton motive force. Tonoplast antiporters are constitutive in halophytes, whereas they must be activated by NaCl in salt-tolerant glycophytes, and they may be absent from salt-sensitive glycophytes. Halophyte vacuoles may have a modified lipid composition to prevent leakage of Na+ back to the cytoplasm [31]. It is also to be noted that halophytes often possess large vacuoles. For example, Suaeda maritime, a potential halophyte, occupies 77% of the mesophyll cells of vacuoles [32] which makes it capable of accumulating higher concentration of salt as much as 500 mM [33]. Moreover, Na+ concentration of the cell sap even exceeded 800 mM in another halophyte, S. maritime [34]. Although all of the halophytes exhibit better accumulation of salt, the level of total salt accumulation in the shoot is mostly species specific, depending on different adaptive strategies ([34]; Figure 4). Based on numerous studies, several adaptative mechanisms were recognized in relation to salt tolerance, which include ion compartmentalisation, osmolyte production, germination responses, osmotic adaptation, succulence, selective transport and uptake of ions, enzyme responses, salt excretion, and genetic control [35].


Potential use of halophytes to remediate saline soils.

Hasanuzzaman M, Nahar K, Alam MM, Bhowmik PC, Hossain MA, Rahman MM, Prasad MN, Ozturk M, Fujita M - Biomed Res Int (2014)

Na+ and Cl− ions concentration in the shoot of some halophytes grown in natural habitats [3] with permission from Springer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109415&req=5

fig4: Na+ and Cl− ions concentration in the shoot of some halophytes grown in natural habitats [3] with permission from Springer.
Mentions: Salinity is not inimical to all plants. The distribution, exploitation [26], and physiology of salt tolerance of halophytes are intensively studied [16, 27, 28]. Salts taken up by halophytes do not directly control plant growth by affecting turgor, photosynthesis, or the activity of one or another enzyme. The build-up of salts in old leaves hastens their death. The loss of leaves affects the supply of assimilates or hormones to the growing organs and hereby affects growth [29, 30]. Despite their polyphyletic origins, halophytes appear to have evolved the same basic method of osmotic adjustment: accumulation of inorganic salts, mainly NaCl, in the vacuole and accumulation of organic solutes in the cytoplasm. Differences between halophyte and glycophyte ion transport systems are becoming apparent. The pathways by which Na+ and Cl− enter halophyte cells are not well understood but may involve ion channels and pinocytosis in addition to Na+ and Cl− transporters. Na+ uptake into vacuoles requires Na+/H+ antiporters in the tonoplast and H+ ATPases and perhaps PPIases to provide the proton motive force. Tonoplast antiporters are constitutive in halophytes, whereas they must be activated by NaCl in salt-tolerant glycophytes, and they may be absent from salt-sensitive glycophytes. Halophyte vacuoles may have a modified lipid composition to prevent leakage of Na+ back to the cytoplasm [31]. It is also to be noted that halophytes often possess large vacuoles. For example, Suaeda maritime, a potential halophyte, occupies 77% of the mesophyll cells of vacuoles [32] which makes it capable of accumulating higher concentration of salt as much as 500 mM [33]. Moreover, Na+ concentration of the cell sap even exceeded 800 mM in another halophyte, S. maritime [34]. Although all of the halophytes exhibit better accumulation of salt, the level of total salt accumulation in the shoot is mostly species specific, depending on different adaptive strategies ([34]; Figure 4). Based on numerous studies, several adaptative mechanisms were recognized in relation to salt tolerance, which include ion compartmentalisation, osmolyte production, germination responses, osmotic adaptation, succulence, selective transport and uptake of ions, enzyme responses, salt excretion, and genetic control [35].

Bottom Line: The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems.Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level.Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well.

View Article: PubMed Central - PubMed

Affiliation: Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka 1207, Bangladesh.

ABSTRACT
Salinity is one of the rising problems causing tremendous yield losses in many regions of the world especially in arid and semiarid regions. To maximize crop productivity, these areas should be brought under utilization where there are options for removing salinity or using the salt-tolerant crops. Use of salt-tolerant crops does not remove the salt and hence halophytes that have capacity to accumulate and exclude the salt can be an effective way. Methods for salt removal include agronomic practices or phytoremediation. The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems. Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level. Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well. This review focuses on the special adaptive features of halophytic plants under saline condition and the possible ways to utilize these plants to remediate salinity.

Show MeSH
Related in: MedlinePlus