Salt Stress Research Papers - Academia.edu (original) (raw)

Summary. In this study, effect of salinity with different osmotic potential on shoot length, total fresh and dry weight, amounts of organic (proline) and inorganic (K+ and Na+) substance of leaf tissue, the Na+/K+ ratio, and leaf area,... more

Summary. In this study, effect of salinity with different osmotic potential on shoot length, total fresh and dry weight, amounts of organic (proline) and inorganic (K+ and Na+) substance of leaf tissue, the Na+/K+ ratio, and leaf area, relative water content (RWC) and leaf osmolality in two maize (Zea mays L., var. intendata, C.6127 and DK.623) cultivars which are grown

A hydroponic experiment was conducted to assess the possible involvement of polyamines (PAs), abscisic acid (ABA) and anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in adaptation of six... more

A hydroponic experiment was conducted to assess the possible involvement of polyamines (PAs), abscisic acid (ABA) and anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in adaptation of six populations of Panicum antidotale Retz. to selection pressure (soil salinity) of a wide range of habitats. Plants of six populations were collected from six different habitats with ECe ranging from 3.39 to 19.23 dS m−1 and pH from 7.65 to 5.86. Young tillers from 6-month-old plants were transplanted in plastic containers each containing 10 l of half strength Hoagland's nutrient solution alone or with 150 mol m−3 NaCl. After 42 days growth, contents of polyamines (Put, Spd and Spm) and ABA, and the activities of anti-oxidative enzymes (SOD, POD and CAT) of all populations generally increased under salt stress. The populations collected from highly saline habitats showed a greater accumulation of polyamines and ABA and the activities of anti-oxidative enzymes as compared to those from mild or non-saline habitats. Moreover, Spm/Spd and Put/(Spd + Spm) ratios generally increased under salt stress. However, the populations from highly saline environments had significantly higher Spm/Spd and Put/(Spd + Spm) ratios as compared to those from mild or non-saline environments. Similarly, the populations adapted to high salinity accumulated less Na+ and Cl− in culm and leaves, and showed less decrease in leaf K+ and Ca2+ under salinity stress. Higher activities of anti-oxidative enzymes and accumulation of polyamines and ABA, and increased Spm/Spd and Put/(Spm + Spd) ratios were found to be highly correlated with the degree of adaptability of Panicum to saline environment.

The changes induced in the levels of proline, tyramine and polyamines in response to salt (NaCl) shock treatments were studied using tomato (Lycopersicon esculentum Mill.) leaf discs incubated in saline media supplemented with various... more

The changes induced in the levels of proline, tyramine and polyamines in response to salt (NaCl) shock treatments were studied using tomato (Lycopersicon esculentum Mill.) leaf discs incubated in saline media supplemented with various concentrations of CaCl2 and KCl. When the leaf discs were subjected to high salinity (100–300 mM NaCl), they accumulated significant amounts of proline (Pro), tyramine, 1,3-diaminopropane (Dap), cadaverine (Cad) and agmatine (Agm) while their free polyamine (PA) content decreased. Under salinized conditions (250 mM NaCl), increase of Pro content in leaf tissues and CaCl2 concentration in the external medium were positively correlated. This correlation was even stronger doubling KCl concentration. Cad and Dap were also accumulated, while tyramine was not significantly modified. In contrast, the amount of free Agm, putrescine (Put), spermidine (Spd) and spermine (Spm) decreased to very low levels. Under non salinized conditions the amount of Put and Spd also decreased in response to the increase of CaCl2 concentration in the external medium and this effect was reinforced in presence of highest concentrations of KCl. While analyzing the changes in the internal ionic status of the leaf explants in response to the salt treatment, it became clear that the internal Na+ and Ca2+ levels exert a positive effect on Pro, tyramine, Agm and Dap levels and a negative one on the levels of Put and Spd. The physiological interest of these responses is discussed.

Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and... more

Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and water, plant hormonal functions, and vital metabolic pathways. Few studies are available on the application of combined nanomaterials to mitigate salinity stress on potato plants (Solanum tuberosum L. cv. Diamont). In order to assess the effects of the sole or combined application of silicon (Si) and potassium (K) nanoparticles and biochar (Bc) on the agro-physiological properties and biochemical constituents of potato plants grown in saline soil, two open-field experiments were executed on a randomized complete block design (RCBD), with five replicates. The results show that the biochar application and nanoelements (n-K and n-Si) significantly improved the plant heights, the fresh and dry plant biomasses, the numbers of stems/plant, the leaf relat...

Background: Bread wheat is one of the most important crops for the human diet, but the increasing soil salinization is causing yield reductions worldwide. Improving salt stress tolerance in wheat requires the elucidation of the... more

Background: Bread wheat is one of the most important crops for the human diet, but the increasing soil salinization is causing yield reductions worldwide. Improving salt stress tolerance in wheat requires the elucidation of the mechanistic basis of plant response to this abiotic stress factor. Although several studies have been performed to analyze wheat adaptation to salt stress, there are still some gaps to fully understand the molecular mechanisms from initial signal perception to the onset of responsive tolerance pathways. The main objective of this study is to exploit the dynamic salt stress transcriptome in underlying QTL regions to uncover candidate genes controlling salt stress tolerance in bread wheat. The massive analysis of 3′-ends sequencing protocol was used to analyze leave samples at osmotic and ionic phases. Afterward, stress-responsive genes overlapping QTL for salt stress-related traits in two mapping populations were identified. Results: Among the over-represented salt-responsive gene categories, the early up-regulation of calcium-binding and cell wall synthesis genes found in the tolerant genotype are presumably strategies to cope with the salt-related osmotic stress. On the other hand, the down-regulation of photosynthesis-related and calcium-binding genes, and the increased oxidative stress response in the susceptible genotype are linked with the greater photosynthesis inhibition at the osmotic phase. The specific up-regulation of some ABC transporters and Na + /Ca 2+ exchangers in the tolerant genotype at the ionic stage indicates their involvement in mechanisms of sodium exclusion and homeostasis. Moreover, genes related to protein synthesis and breakdown were identified at both stress phases. Based on the linkage disequilibrium blocks, salt-responsive genes within QTL intervals were identified as potential components operating in pathways leading to salt stress tolerance. Furthermore, this study conferred evidence of novel regions with transcription in bread wheat. Conclusion: The dynamic transcriptome analysis allowed the comparison of osmotic and ionic phases of the salt stress response and gave insights into key molecular mechanisms involved in the salt stress adaptation of contrasting bread wheat genotypes. The leveraging of the highly contiguous chromosome-level reference genome sequence assembly facilitated the QTL dissection by targeting novel candidate genes for salt tolerance.

In this review, we will try to summarize some recent data concerning the changes in polyamine metabolism (biosynthesis, catabolism and regulation) in higher plants subjected to a wide array of environmental stress conditions and to... more

In this review, we will try to summarize some recent data concerning the changes in polyamine metabolism (biosynthesis, catabolism and regulation) in higher plants subjected to a wide array of environmental stress conditions and to describe and discuss some of the new advances concerning the different proposed mechanisms of polyamine action implicated in plant response to environmental challenges. All the data support the view that putrescine and derived polyamines (spermidine, spermine, long-chained polyamides) may have several functions during environmental challenges. In several systems (except during hypoxia, and chilling tolerance of wheat and rice) an induction of polyamines (spermidine, spermine) not putrescine accumulation, may confer a stress tolerance. In several cases stress tolerance is associated with the production of conjugated and bound polyamines and stimulation of polyamine oxidation. In several environmental challenges (osmotic-stress, salinity, hypoxia, environmental pollutants) recent results indicate that both arginine decarboxylase and ornithine decarboxylase are required for the synthesis of putrescine and polyamines (spermidine and spermine). Under osmotic and salt-stresses a production of cadaverine is observed in plants. A new study demonstrates that under salt-stress putrescine catabolism (via diamine oxidase) can contribute to proline (a compatible osmolyte) accumulation.

Factorial field experiments was conducted during 2012/2013 growth season to study the effect of soil mulch (mulch and without mulch) and some fertilizers (control, sulfur, organic and high potash fertilizer) on H2O2 content and the... more

Factorial field experiments was conducted during 2012/2013 growth season to study the effect of soil mulch (mulch and without mulch) and some fertilizers (control, sulfur, organic and high potash fertilizer) on H2O2 content and the activity of catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH) oxidative enzymes of broccoli leaves and flowers. The results showed that using mulch, fertilizer treatment and the interaction between mulch and high potash treatment led to a significant increase in CAT and SOD activity. Furthermore, high potash and sulfur supplementation caused a significant increase in broccoli antioxidants both in leaves and flowers respectively. We conclude that mulch and high potash treatment led to increase plant tolerance to salt stress by increasing antioxidant mechanisms.

Salt stress is primarily osmotic stress, and halophilic/halotolerant microorganisms have evolved two basic mechanisms of osmoadaplation: the KCI-type and the compatible-solute type, the latter representing a very flexible mode of... more

Salt stress is primarily osmotic stress, and halophilic/halotolerant microorganisms have evolved two basic mechanisms of osmoadaplation: the KCI-type and the compatible-solute type, the latter representing a very flexible mode of adaptation making use of distinct stabilizing ...

The possible involvement of activated oxygen species in the mechanism of damage by NaCl stress was studied in leaves of four varieties of rice (Oryza sativa L.) exhibiting different sensitivities to NaCl. The 3-week-old rice seedlings... more

The possible involvement of activated oxygen species in the mechanism of damage by NaCl stress was studied in leaves of four varieties of rice (Oryza sativa L.) exhibiting different sensitivities to NaCl. The 3-week-old rice seedlings were subjected to 0, 6 and 12 dS m −1 salinity ...

High salinity increases antioxidative activities in plants; however, their significance for overall plant salt tolerance remains to be established. This work provided in vivo evidence of salinity induced biphasic reactive oxygen species... more

High salinity increases antioxidative activities in plants; however, their significance for overall plant salt tolerance remains to be established. This work provided in vivo evidence of salinity induced biphasic reactive oxygen species (ROS) accumulation evoking oxidative stress in the cyanobacterium Anabaena fertilissima. First, a transient increase in ROS (intense and short-lived) was observed within 5 min of salt exposure, which peaked within 15 min and reached basal level by 2 h. This was followed by a second relatively long-lived and low magnitude ROS accumulation that started at 4 h of salt stress, attained its maximal at 6 h, followed by a gradual decline but did not attain the basal level by the end of experimentation (12 h). Phase I ROS accumulation timing corresponded to the reaction of cyanobacterial cells to the salt stress, while altered photosynthetic and respiratory parameters corresponded with the phase II ROS generation. Relatively lower magnitude of ROS generation during phase II may be attributed to the rapid activation of robust antioxidative systems in cyanobacteria. Consequently , ROS generation lead to the activation of programmed cell death (PCD) undergoing various apoptotic stages such as externalization of phosphatidylserine, DNA laddering and loss of plasma membrane integrity. A. fertilissima exposed to salt in the presence of SO 4 ¯ was relatively better equipped to deal with salt stress.

The influence of seed priming using different priming agents (distilled water, NaCl, salicylic acid, acetyl salicylic acid, ascorbic acid, PEG-8000 and KNO3) on seed vigour of hot pepper cv. Hot Queen was examined. Primed seeds of each... more

The influence of seed priming using different priming agents (distilled water, NaCl, salicylic acid, acetyl salicylic acid, ascorbic acid, PEG-8000 and KNO3) on seed vigour of hot pepper cv. Hot Queen was examined. Primed seeds of each treatment were cultured in Petri ...

El arándano azul (Vaccinium corymbosum L.), es un cultivo de importancia mundial, que ha tenido relevancia los últimos años debido a su gran beneficio para la salud humana, ya que es una gran fuente de antioxidantes. En el año 2016,... more

El arándano azul (Vaccinium corymbosum L.), es un cultivo de importancia mundial, que ha tenido relevancia los últimos años debido a su gran beneficio para la salud humana, ya que es una gran fuente de antioxidantes. En el año 2016, México ocupó el cuarto lugar con una producción de 18.031 t, de las cuales se exportaron 17.345 t con un valor comercial de 187,9 millones de dólares (Organización de las Naciones Unidas para la Alimentación y la Agricultura [FAO], 2020).
El estrés osmótico, o lo que es consecuencia del mismo el estrés hídrico y salino, es uno de los prin¬cipales factores de estrés abiótico con efecto negativo en la producción de plantas cultivadas en el mundo. El arándano se ve sumamente afectado en rendimiento cuando se desarrolla en condiciones en las que se tenga arriba de 1 dS/m de conductividad eléctrica.
La Glicina-betaína es un compuesto cuaternario del amonio, clasificado como un bioestimulante. Se ha demostrado que la GB, Protege al fotosistema II contra el fotodaño inducido por la sal (T. Chen y N. Murata, 2010). Esto de traduce en una respuesta antiestresante para las plantas, y eventualmente se logra en una mayor eficiencia en procesos como fotosintesis y producción de biomasa en condiciones de salinidad.

Enzymatic activity and soluble protein content in relation to salt stress tolerance were investigated in Calendula officinalis seedlings after 24 days of treatment with different salt treatments, including NaCl, CaCl2, MgCl2 and mixtures... more

Enzymatic activity and soluble protein content in relation to salt stress tolerance were investigated in Calendula officinalis seedlings after 24 days of treatment with different salt treatments, including NaCl, CaCl2, MgCl2 and mixtures of them. The marigold seedlings were used in order to investigate the possible salt-inducible responses and the possible alleviative role of calcium and magnesium salts in respect with adverse salinity conditions. Activity of superoxide dismutase (SOD; EC 1.15.1.1) and peroxidase (POD; EC 1.11.1.7) generally slightly decreased under salt treatments, with minor variations from the value recorded for control series and within applied treatments. Catalase (CAT; EC 1.11.1.6) activity was stimulated by NaCl salinity and MgCl2 addition; its activity was found to be lowest under calcium and magnesium chloride treatments solely.

Soil and irrigation water salinity are among the main problems hindering agricultural development, especially in arid and semi-arid regions, which depends on especially surface irrigation as the main means in agriculture. The salinity... more

Soil and irrigation water salinity are among the main problems hindering agricultural development, especially in arid and semi-arid regions, which depends on especially surface irrigation as the main means in agriculture. The salinity lead to low growth and production of plants, including fruit, as a result of the temporal, azalotic, or nutrients imbalance. Salinity of the soil or irrigation water greatly reduces the growth, productivity and quality of fruit crops by affecting their physiological, chemical and biological functions as they cause obstruction to the absorption of some elements by the plant and if it increased absorption of salts, it causes ion poisoning of the cell, as well as increased salts cause less absorption of water by the plant due to the high osmosis of soil water. There are many ways to reduce the salt stress in the growth of fruit plants, the most important of which is adding organic fertilizers such as humic acid or spraying with the amino acid proline.

Organic food is getting much preference worldwide because they are free of diseases pure and possess good physiochemical features. Taking the beneficial impact of organic production, into account, this study was conducted under a poly... more

Organic food is getting much preference worldwide because they are free of diseases pure and possess
good physiochemical features. Taking the beneficial impact of organic production, into account, this
study was conducted under a poly tunnel system using five organic media mixtures including. T0:
(Control) Soil + Sand (1: 1), T1 Soil + Silt + Farm Yard Manure (1: 1: 1), T2: Soil + Silt + Leaf Manure (1: 1:
1), T3: Soil + Silt + Poultry Manure (1: 1: 1) and T4: Soil + Silt + Coconut Coir Dust (1: 1: 1). Effects of
these growing media on the reproductive growth parameters and subsequently on the quality of
parameter of its fruit strawberry (Fragaria annanasa Duch.) cv. “Chandler” were recorded by using
randomized complete block design (RCBD) with three replicates. Result showed that different
reproductive growth parameters of the strawberry plant were also affected by the different growing
media. It was observed that coconut coir dust based medium (T4) proved to be the best medium in many
aspects. Treatment T4 produced favorable effects on other relevant growth stages. Its influence was
also positive on the average number of trusses with (4.33), average number of flowers per truss (6.33),
average number of flowers (96), flower size (1.90 cm), average number of fruit set (16.00), average
number of fruits (72.96) and fruit size (3.01 cm). Improvement in the fruit weight was observed on T3
(10.0 g). Effect of T4 growing medium was also prominent on fruits color with maximum value of
luminance, L* (32.67), redness, a* (29.00), chromaticity, C* (26.00) with low value of b* (7.500) and hue
angle, h° (14.00) due to which fruits were more bright and reddish in color. Moreover it also improved
the ascorbic acid contents (68.00 mg 100-1 ml) in fruits. The growing medium, T1 improved the total
soluble solids (6.26%) of the fruits with an additional improvement in total sugars (15.92%). A significant
effect on total sugars was also induced by T4 (15.22%) in strawberry fruits.

The ability to tolerate elevated concentrations of sodium chloride varies between different microorganisms. Chlorophytes (green algae) such as A. falcatus are a potential source of lipid biofuels, and maximization of their biomass... more

The ability to tolerate elevated concentrations of sodium chloride varies between different microorganisms. Chlorophytes (green algae) such as A. falcatus are a potential source of lipid biofuels, and maximization of their biomass productivity depends in part on determining optimal NaCl concentrations for growth. Our objectives were to (1) determine the magnitude and direction of the relationship between biomass productivity (measured via cell density) and salinity of the growth medium in A. falcatus, and (2) estimate the minimum inhibitory concentration (MIC) of sodium chloride for this freshwater species of green algae. A. falcatus cell cultures were grown for one week at 22°C under natural lighting conditions in filtered lake water, to which varying amounts of NaCl solution were added. Sample absorbance was measured at 665 nm and converted to cell densities, which were used to generate two linear regression models for the relationship between cell density and NaCl concentration and to estimate the MIC of NaCl. In both Model 1 (all treatments) and Model 2 (excluded 1694 mM), there was a highly significant negative correlation between cell density and NaCl concentration (-0.829, -0.847 (p<0.0001), respectively). β-coefficients differed between regression models, suggesting possible nonlinearity of growth inhibition across a concentration range of 0-1694 mM. The lowest NaCl concentration at which a significant difference was observed between treatments as compared to the freshwater control was 200 mM NaCl (p<0.05), which approximated the MIC of sodium chloride in A. falcatus. However, algal growth was observed at all concentrations, and the extent of inhibition was stable across NaCl concentrations above 200 mM. In conclusion, a strongly negative correlation appears to exist between biomass productivity and NaCl concentration in this particular strain of A. falcatus. Furthermore, 200 mM serves as a valid first approximation of the MIC of NaCl in A. falcatus. Finally, because A. falcatus is able to thrive in hypersaline conditions (1694 mM), this species of green algae warrants further investigation as a salt-tolerant source of lipid biofuels which may be grown in saline-diverse conditions. (Acknowledgements: data were collected by Camilla Wang, David Rapoport, and myself.)

The seeds of thirteen varieties of Pearl millet (Pennisetum glaucum (L.)) were evaluated for enzyme activity in response to sulphate base salinity. Sterilized seeds were safely maintain in filter paper lined Petri dishes and irrigated... more

The seeds of thirteen varieties of Pearl millet (Pennisetum glaucum (L.)) were evaluated for enzyme activity in response to sulphate base salinity. Sterilized seeds were safely maintain in filter paper lined Petri dishes and irrigated with water or salt solution (00, 40, 80, 120 m.eq/L). Practice was maintained for the filter paper kept moist by periodic additions of salt solution or water for the required treatments. The research carried out on sulphate dominant salinity. Enzymatic study protease and peroxidase activity increased with increase in salinity, while in case alfa amylase activity, it decreased with increasing salinity level. There was significant interacting effect between salinity treatments and varieties of pearl millet with respect to enzyme activities.

Academic Editor: Md. Rashedur Rahman Mungbean is severely affected by salt stress causing significant yield loss. Therefore, cultivation of salt tolerant cultivar and alleviation of saline stress are very important for successful... more

Academic Editor: Md. Rashedur Rahman Mungbean is severely affected by salt stress causing significant yield loss. Therefore, cultivation of salt tolerant cultivar and alleviation of saline stress are very important for successful production of mungbean in coastal areas. Laboratory experiments were conducted for screening salt tolerance of mungbean genotypes and to alleviate salinity stress through gypsum fertilization. For screening test eleven mungbean genotype (BARI mung 2, BARI mung 3, BARI mung 4, BARI mung 5, BARI mung 6, BINA mung 1, BINA mung 2, BINA mung 5, BINA mung 6, BINA mung 7 and BINA mung 8) were tested in three salinity levels (0, 50 and 100 mM) of NaCl. The seedling growth characteristics of all mungbean genotypes were reduced with increasing level of salinity compared to control. BINA mung 8 showed better performances in terms shoot and root growth (length, fresh and dry weights) and BARI mung 2 showed lowest performances in saline environment. Results on seedling growth indicate that BINA mung 8 was more tolerant and BARI mung 2 was more sensitive. BINA mung 8 was also used for alleviation of salinity through gypsum (CaSO4.2H2O) application at five different treatments (Control, 50 mM NaCl, 100 mM NaCl, 50 mM NaCl +10 mM gypsum and 100 mM NaCl +10 mM gypsum). Most of the morphological characters viz., length of shoot and root, branches plant-1 , weight of leaf, stem, root, yield and yield contributing characters (pods plant-1 , seeds plant-1 , 1000 seed weight) performed better at 50 mM NaCl with 10 mM gypsum level, and showed lower performance in respect of above terms at 100 mM saline condition. Therefore, BINA mung 8 should be cultivated in saline soil by the application of 10 mM gypsum at three growth stage viz., pre-flowering, flowering and pod formation stage. The study revealed that gypsum treatment could alleviate the adverse effect of salinity on mungbean.

In hot arid lands, soil salinity, irrigation with brackish waters and the massive use of mineral fertilizers are major constraints for the development of potato cropping. The current field experiment was conducted in the Sahara Desert of... more

In hot arid lands, soil salinity, irrigation with brackish waters and the massive use of mineral fertilizers are major constraints for the development of potato cropping. The current field experiment was conducted in the Sahara Desert of Algeria in order to highlight the effect of organic fertilization on the improvement of potato production and the increase of plant salt-stress tolerance. The variation of yield production parameters and nutritional status of plants were evaluated through a split-plot design including six increasing rates of poultry manure (PM) (0, 20, 30, 40, 50, 60 mt/ha) tested in three experimental sites with increasing salinity levels: low saline soil (electrical conductivity ‘EC’ = 0.9 dS/m), saline soil (EC = 2.2 dS/m) and high saline soil (EC = 5.9 dS/m). The results revealed a significant and proportional increasing of all studied yield parameters (number, seize and yields of tubers) with the increase of PM rates compared to the control. The effect of the interaction (PM × salinity level) showed that the highest yield (44.55 mt/ha) was recorded in plots treated with 60 mt/ha of PM in high saline soils. The assessment of nutritional status at flowering stage of potato plants demonstrated that concentrations of K+ and N increased while Na+ concentrations decreased, in both leaves and roots, as PM rates increasing, principally beneath high salinity level. Our findings suggest the dose of 60 mt/ha of PM is an optimal amount producing the best tuber yields under saline conditions in arid soils.

Salinity affects plant growth and development in various ways through its impact on photosynthesis, water relations and nutrient absorption. Additionally, the biochemical composition of plants is also affected by salinity through changes... more

Salinity affects plant growth and development in various ways through its impact on photosynthesis, water relations and nutrient absorption. Additionally, the biochemical composition of plants is also affected by salinity through changes in the concentration and type of proteins, amino acids, sugars and other carbohydrates. This chapter elucidates with examples the changes that occur in the plant‟s physiological functions and biochemical composition as a result of increased salinity of the plant‟s environment. It is highlighted that the fundamental mechanism of salinity‟s effects on plant function is the increase in the osmotic pressure of the plant‟s environment that inhibits the absorption of water and nutrients. Invariably, salinity inhibits photosynthesis through its effects on stomatal conductance, water and nutrient uptake and decrease in the chlorophyll concentration. Subsequently, higher levels of salinity create an excessive accumulation of salts in plant tissues that causes toxicity. Prolonged salinity will thus reduce plant growth and yield and with increasing severity of salinity, toxic levels of salts that build up in plant tissues will further aggravate the stress. Plants exhibit several mechanisms that can alleviate the deleterious effects of salinity including compartmentalization of ions, synthesis of compatible solutes, induction of plant hormones and alteration of membrane structure.
Key Words: Biochemical response, plant physiology, crops, salinity, stresses

Salinity has been an important historical factor which has influenced the life span of agricultural systems. Around 10% of the total cropped land surface is covered with different types of salt-affected soils and the Asian continent... more

Salinity has been an important historical factor which has influenced the life span of agricultural systems. Around 10% of the total cropped land surface is covered with different types of salt-affected soils and the Asian continent accounts for the largest area affected by the salinity of various intensities. Cyanobacteria are capable of not only surviving, but thriving in conditions which are considered to be inhabitable, tolerating desiccation, high temperature, extreme pH and high salinity, illustrating their capacity to acclimatise to extreme environments. Until recently, the responses of cyanobacteria to salinity stresses were poorly documented as compared to heterotrophic bacteria and phototrophic eukaryotic algae. Cyanobacteria can be used to reclaim alkaline soils and fertility can be improved for subsequent cultivation of cereal crops, sugarcane and horticultural crops. Therefore we present here a review on cyanobacterial reclamation of salt-affected soil. Substantial progress has been made towards better understanding of the physiological mechanisms responsible for salinity tolerance and osmotic adjustment in cyanobacteria. Many researchers throughout the world have worked on probable mechanisms of salt tolerance studies in cyanobacteria. These organisms evolved about 3,000 million years ago and are considered to be the primary colonisers of the inhospitable ecosystems. The physiological aspects for the adaptation of cyanobacteria to high salinities include (a) synthesis and accumulation of osmoprotective compounds, (b) maintenance of low internal concentrations of inorganic ions and (c) expression of a set of salt-stress proteins. Exposure of cyanobacterial cells to different abiotic stresses resulted in rapid expression of several stress-regulated proteins and modifications in protein synthesis programme. The synthesis of organic solutes like disaccharides (sucrose, trehalose and glucosyl glycerol), quaternary amines (glycine betaine) and free amino acids (glutamine) are well-documented. The protection against alkaline environment is provided by the synthesis of specific fatty acids, sucrose- and osmotic-stress-induced proteins. In cyanobacteria, accumulation of internal osmoticum in the form of inorganic ions and prevention of intracellular Na+ accumulation by the curtailment of Na influx and by efficient active efflux mechanisms or metabolic adjustments have been investigated in depth. The Na+ extrusion in cyanobacteria is driven by a Na+/H+ antiporter, which is energised by enhanced activity of cytochrome oxidase. The inhibition of sodium ion influx appears to be a major mechanism for the survival of cyanobacteria against salt stress and synthesis of salt-stress proteins have been found in cyanobacteria. These organisms have been recognised as an important agent in the stabilisation of soil surfaces primarily through the production of extracellular polysaccharides which are prominent agents in the process of aggregate formation and increase in soil fertility. Cyanobacterial application results in the enrichment of soil with fixed nitrogen, soil structure improvement and declining trend of pH, electrical conductivity (EC) and Na+. The extracellular polysaccharides excreted by cyanobacteria have been reported to be responsible for binding of soil particles, thus, leading to the formation of a tough and entangled superficial structure that improves the stability of soil surface and protects it from erosion. The potential impact of these organisms on agriculture through their use as soil conditioners, plant growth regulators and soil health ameliorators has been well-recognised. Besides bringing about an improvement in the yield of rice, cyanobacteria produce direct and indirect beneficial changes in the physical, chemical and biological properties of soil and soil–water interface in the rice fields, which are of agronomic importance. Certain cyanobacteria have been found not only to grow in saline ecosystems but also improve the physico-chemical properties of the soil by enriching them with carbon, nitrogen and available phosphorus. Flushing of field may not be effective for the reclamation of saline soils and the addition of cyanobacterium inoculum along with the addition of gypsum is required before irrigation to ameliorate saline soils. Nitrogen-fixing cyanobacteria can be used as biological input to improve soil texture, conserve moisture, scavenge the toxic sodium cation from the soil complex and improve the properties of soils. Virtually negligible information exists on the genetics of cyanobacterial halotolerance. The presence of combined nitrogen which effectively curtails sodium accumulation and supports extra nitrogen demand for osmoregulation during slat stress confers considerable salt tolerance on cyanobacteria.

High salt concentration represents one of the most significant abiotic constraints, affecting all life forms including plants and cyanobacteria. Soil salinity curtails plant growth by way of osmotic, ionic and oxidative stresses resulting... more

High salt concentration represents one of the most significant abiotic
constraints, affecting all life forms including plants and cyanobacteria. Soil salinity
curtails plant growth by way of osmotic, ionic and oxidative stresses resulting in
multiple inhibitory effects on various physiological processes such as growth,
photosynthesis, respiration and cellular metabolism. In order to combat high salinity,
various adaptive strategies employed include ion homeostasis achieved by ion
transport and compartmentalization of injurious ions, osmotic homeostasis by
accumulation of compatible solutes/osmolytes and upregulation of antioxidant
defence mechanism. The aforesaid processes are executed through SOS and
MAPK signalling pathways leading to modulation of gene expression. Salt stress
signal transduction pathways initiate through sensing extracellular Na+ ions causing
modification of constitutively expressed transcription factors. This modification is
responsible for expression of early transcriptional activators such as CBF/DREB
gene family which eventually activate stress tolerance effector genes such as
osmolyte biosynthesis genes, detoxification enzymes, and chaperones. Various
genes/cDNAs encoding proteins involved in these adaptive mechanisms have
been isolated and identified. Bioinformatic predictions through docking revealed
interaction of salt across the species at conserved domains and motifs as a possible
mechanism for response of a particular protein under salt stress. In this chapter,
major aspects of salt stress are reviewed with emphasis on its detrimental consequences
and biochemical and molecular mechanisms of signal transduction in
plants and cyanobacteria under high salinity.

Phytohormones are chemical substances that induce physiological responses in plants in minute concentrations. Apart from the classical five phytohormones viz., auxins, gibberellins, cytokinins, ethylene and abscisic acid, there are other... more

Phytohormones are chemical substances that induce physiological responses in plants in minute concentrations. Apart from the classical five phytohormones viz., auxins, gibberellins, cytokinins, ethylene and abscisic acid, there are
other well-known phytohormones like brassinosteroids, methyl jasmonates, salicylic acid, strigolactones etc., that have a profound role during abiotic stress tolerance. Plants are
prone to various abiotic stresses like heat, chilling, freezing, drought, flooding, oxidative, salt, allelochemicals, radiation, light, wind, heavy metals stresses etc. Among the various abiotic stresses in plants, salt stress is an important aspect that hinders growth, metabolism and final yields of plants. The roles of above mentioned phytohormones which can alleviate the salt stress are slowly unfolding. The present review deals with the role of the phytohormones on the
alleviation of salt stress in plants.

The increasing seriousness of salinization aggravates the food, population and environmental issues. Ameliorating the salt-resistance of plants especially the crops is the most effective measure to solve the worldwide problem. The... more

The increasing seriousness of salinization aggravates the food, population and environmental issues. Ameliorating the salt-resistance of plants especially the crops is the most effective measure to solve the worldwide problem. The salinity can cause damage to plants mainly from two aspects: hyperosmotic and hyperionic stresses leading to the restrain of growth and photosynthesis. To the adverse effects, the plants derive corresponding strategies including: ion regulation and compartmentalization, biosynthesis of compatible solutes, induction of antioxidant enzymes and plant hormones. With the development of molecular biology, our understanding of the molecular and physiology knowledge is becoming clearness. The complex signal transduction underlying the salt resistance is being illuminated brighter and clearer. The SOS pathway is the central of the cell signaling in salt stress. The accumulation of the compatible solutes and the activation of the antioxidant system are the effective
measures for plants to enhance the salt resistance. How to make full use of our understanding to improve the output of crops is a huge challenge for us, yet the application of the genetic engineering makes this possible. In this review, we will discuss the influence of the salt stress and the response of the plants in detail expecting to provide a particular account for the plant resistance in molecular, physiological and transgenic fields.