Excessive salt above what plants need limits plant growth and productivity and can lead to plant death. Genotype br5011 suffered the largest growth reduction while the smallest reduction was observed for genotype br5033, suggesting that the former is the most saltsensitive and the latter the most salttolerant figure 1. Proline and salinity tolerance in plants longdom publishing sl. Overexpression of zmcipk21 enhanced salt tolerance in arabidopsis previously, we had reported that zmcipk21 was upregulated in response to salt stress 15. Salt tolerance of plants varies greatly during plant development and different growth phases of the plant. Summary abiotic stress is responsible for the loss of crop yield and 17% and 20 % crop loss is estimated by drought and salinity stress. Our study focused on the effects of dse on salt tolerance, and specifically looked at nacl as a stress factor. Zmcipk21, a maize cblinteracting kinase, enhances salt. Oxidative stress due to increase in salinity stress, photosynthetic rate decreases which increases the formation of reactive oxygen species ros, and increases the activity of enzymes that detoxify these species. Pdf salt stress is one of the most devastating abiotic stress which severely affects the agricultural productivity in various ways. Salt tolerance in crops will also allow the more effective use of poor quality irrigation water. For more information on the harmful effects of abiotic stress, see the sections below on plants and animals. Most plants avoid salinity, some evade or resist salinity, and a few actually tolerate salinity.
Plant growth regulators and their role in stress tolerance. Here, we characterized a novel gene at5g39520 in arabidopsis, which is induced by salt stress and encodes a chloroplastlocalized protein. Overexpression of rice expansin7 osexpa7 confers enhanced. Salt stress has a major impact on plant growth and crop production, pointing to the importance of understanding the mechanism of salt tolerance in plants. Selection for highyielding, salt tolerant cultivars has proven to be an elusive target for plant of breeders, and the identification reliable genetic markers for salt tolerance has been even more elusive for plant physiologists, and cellular and molecular biologists. Salt and drought stress signal transduction in plants. Rice plants show tolerance to salt stress via two mechanisms known as ion exclusion and osmotic. High concentration of salt in the soil or in the irrigation water can have a overwhelming effect on plant metabolism, disrupting cellular homeostasis and uncoupling major physiological and biochemical processes. Pdf endophytic bacteria in plant salt stress tolerance. New insights on plant salt tolerance mechanisms and their. Saltinduced chloroplast protein scp is involved in. Disruption of the proteinfolding capacity in the endoplasmic reticulum er induces the accumulation of unfolded protein and er stress, which activates an unfolded protein response upr. Salt stress signaling and mechanisms of plant salt tolerance. In this paper, the salt tolerance mechanism of plants is described from four aspects.
Microalgae are known to respond to salinity stress via mechanisms that include accumulation of compatible solutes and synthesis of antioxidants. The ionic aspect of salt stress is signaled via the sos pathway where a calciumresponsive sos3sos2 protein kinase complex controls the expression and activity of ion transporters such. This observation may be explained by one or more of the following models. Therefore, developments of salt tolerant crops can be the best and most practical way to produce enough food. Plant hormones have long been considered as essential endogenous molecules involved in regulating plant development and tolerance or susceptibility of diverse stresses including salinity stress.
Phytohormones are chemical substances that induce physiological responses in plants in minute concentrations. Understanding the molecular basis will be helpful in developing. In plants, salt stress will occur as a result of excess salinity in the soil surrounding plant roots, which in turn can lead to death or negatively impact plant growth and development. Salt stress reduced plant growth of all genotypes but the genotypes br5033 and br5011 were characterized as the most salttolerant and saltsensitive, respectively. A salt tolerant cell does not necessarily make a salt tolerant plant. In the alga parachlorella kessleri grown under salt stress conditions, we observed significant increases in cell size and ld content.
There has been progress in methods of identifying genes underlying. Pdf salt stress signaling and mechanisms of plant salt. The first model is that too much ip 3 may compromise stress tolerance. Of the cereals, rice oryza sativa is the most sensitive and barley hordeum. Biotechnological approaches have improved a lot in understanding the mechanisms of salt tolerance in plants.
Mechanisms of plant response to salt and drought stress. Conventional selection and breeding techniques have been used to improve salinity tolerance in crop plants ashraf 2002. Molecular plant volume 2 number 3 pages 526534 may 2009 research article prefoldins 3 and 5 play an essential role in arabidopsis tolerance to salt stress miguel a. Tolerance mechanism of plants towards salinity is still a debated question. Arabidopsis early flowering3 increases salt tolerance by suppressing salt stress response pathways yasuhito sakuraba1, selin bulb ul 2, weilan piao1, giltsu choi3 and namchon paek1, 1department of plant science, plant genomics and breeding institute, and research institute of agriculture and life sciences, seoul national university, seoul 08826, korea. Recently, studies have shown that the exogenous application of melatonin improves plants ion homeostasis under salt stress. Salt tolerance is the relative ability of a plant to endure the effects of excess salts in the soil rooting medium in order to produce a satisfactory stand or yield. In the course of evolution, plants have developed several protecting mechanisms avoidance and tolerance so as to adapt to salt stress.
Therefore, we generated transgenic arabidopsis plants overexpressing zmcipk21 and examined the growth of these transgenic plants under salt stress. Effects of salinity and drought on growth, ionic relations. In this context, engineering crops to enhance salt tolerance mechanisms is a promising approach to address these challenges. However, it remains largely unknown how the chloroplastlocalized proteins affect plant response to salt stress. This section is referencing only the plant s observed tolerance or sensitivity to salt in the soil. Maintaining adequate soil water throughout the growing season is also essential to obtain reliable data. Dark septate endophyte improves salt tolerance of native. Salt stress is one of the major abiotic threats to plant life and plant agriculture worldwide and significantly reduces crop yield in affected areas. Although those species are grown at a much lower scale than major food, feed or fiber crops. Plant hormones in salt stress tolerance springerlink.
Salt stress induced plant senescence and chloroplast degradation. Salt stress causes an imbalance of cellular ions resulting in ion toxicity. The bases for plant variation in tolerance plants vary in tolerance plants differ greatly in their tolerance of salinity, as re. Here, we describe a salinity tolerance mechanism mediated by lipid droplets lds. There is only anecdotal information about salt tolerance in trees, much of which doesnt differentiate between spray and soil. Pdf soil salinity is a major abiotic stress affecting the performance of crop plants around the world adversely.
Application of hormones proved effective salt stress ameliorating approach. Salinity stress negatively impacts agricultural yield throughout the world affecting production whether it is for subsistence oreconomic gain. Moreover the salt induced inhibition of the up take of. Physiological mechanisms of salt stress tolerance in plants plant.
A novel approach to assess salt stress tolerance in. Effects of abiotic stress on plants the university of. Treatment of roots with mature ralf2223 peptides or salt stress causes the internalization of fer. Pdf role of phytohormones during salt stress tolerance. Review article molecular mechanisms of plant salinity. Stomatal response of the salttolerant genotype was not affected by salinity. To increase the plant salt tolerance, there is a need for understanding the mechanisms of salt limitation on plant growth and the mechanism of salt tolerance at the whole plant, organelle, and molecular levels. Salt stress promotes s1p proteasedependent release of mature ralf22 peptides. A wide range of studies and practices have been performed to induce salt tolerance mechanisms in plants, but their result in crop improvement has been limited due to lack of time and money.
Ecophysiology and responses of plants under salt stress. A plants first line of defense against abiotic stress is in its roots. Ros homeostasis in halophytes in the context of salinity. Salt stress tolerance level varies from one species to another and, for cereal crops, bread wheat is a moderately salttolerant crop maas and. Salt adaptation, ion homeostasis, transport determinants, stress singnaling. In several transgenic plants, overexpression of atnhx1 gene was reported to enhance plant salt tolerance considerably. Publications a variety of sorghum, sensitive to salinity, growing in sand culture and watered with a nutrient solution containing increasing concentrations of. Pdf plant growth regulators and their role in stress. Leucinerich repeat extensin proteins regulate plant salt. Sugar beets, a species with fairly high salt tolerance during vegetative growth, is more sensitive to salinity during germination than corn, which is saltsensitive during growth. Contrary to the notion that multiple traits introduced by breeding into crop plants are needed to implement salt tolerant plants, one of the main strategies for improving plant salt tolerance has been through the overexpression of single genes that are either induced by stress andor have been shown to be required for normal levels of tolerance.
Effects of salt stress on plant growth, stomatal response. Salinity cause both osmotic stress and ionic toxicity which hamper the plant productivity. As discussed above, it is very intriguing that fry1 mutant plants are less tolerant to salt, drought, or freezing stress despite enhanced expression of stress genes in the mutant. This has led to research into salt tolerance with the aim of improving crop plants. Skip confers osmotic tolerance during salt stress by. Arabidopsis early flowering3 increases salt tolerance by. The root is the first organ that responds to salt stress and plays an important role in salinity response 7.
If water is limiting, plants not only must endure water stress, but they are exposed to higher salt concentrations as they extract and concentrate the soil water. Salt and drought stress signal transduction consists of ionic and osmotic homeostasis signaling pathways, detoxification i. There are numerous potential solutions for mitigating salt stress, including genetic engineering of plants with salt tolerance agarwal et al. Halophytes are defined as plants that are adapted to live in soils containing high concentrations of salt and benefiting from it, and thus represent an ideal model to understand complex physiological and genetic mechanisms of salinity stress tolerance. Ecophysiology and responses of plants under salt stress this book will shed light on the effect of salt stress on plants development, proteomics, genomics, genetic engineering, and plant adaptations, among other topics.
A bifunctional xyloglucan galactosyltransferase is an. Salt stress tolerance is a complex trait, so the qtls related with salt tolerance have significant role in understanding the stress response and generating stress tolerant plants gorantla et al. Development of salt stress tolerance screening and. Salt stress imposes ion toxicity, nutrient deficiency, osmotic. Our results suggest that the lrxs, ralfs, and fer function as a module to transduce cellwall signals to regulate plant growth and salt stress tolerance. Among many glycoproteins within the plant secretory system, korrigan1 kor1, a membraneanchored endo. Salinity stress is one of the more prevailing abiotic stresses which results in significant losses in agricultural crop production, particularly in arid. Plant hormones in salt stress tolerance request pdf. Plant adaptations to salinity are of three distinct types.
Plants, as a sessile organism, rely on the endogenous regulators for the modulation of growth and development under severe stress conditions for their survival. After insertion into the endoplasmic reticulum, kor1 cycles between the transgolgi network tgn and the plasma. Omic approach is one of the recent tools that help us in understanding the physiology and biochemistry of the cells under salinity stress. Because abiotic stress is widely considered a detrimental effect, the research on this branch of the issue is extensive. Salt stress is one of most dramatic abiotic stresses, reduces crop yield significantly. However, salt tolerance might have much wider implications because transgenic salt tolerant plants often also tolerate other stresses including chilling, freezing, heat and drought. Soil salinity is a major limiting factor for crop productivity worldwide and is continuously increasing owing to climate change. Skip confers osmotic tolerance during salt stress by controlling alternative gene splicing in arabidopsis jinlinfeng 1, 24,jingjingli,zhaoxugao 1,3 4,yarulu,junyayu,qianzheng,shuningyan, wenjiao zhang 1, hang he3, ligeng ma2, and zhengge zhu, 1college of life sciences, hebei normal university, shijiazhuang, hebei 050021, china 2college of life sciences, capital normal university. Summary abiotic stress is responsible for the loss of crop yield and 17% and 20% crop loss is estimated by drought and salinity stress. The plant response to salinity consists of numerous processes that must function in coordination to alleviate both cellularhyperosmolarity and ion disequilibrium. Upregulation of several genes in response to salt stress are kmt1 and various hakkup types of genes. Soil salinity is a major abiotic stress in plant agriculture worldwide.