Intra and Inter-specific Variability of Salt Tolerance Mechanisms in Diospyros Genus (original) (raw)
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Agronomy
Agriculture needs solutions for adapting crops to increasing salinity globally. Research on physiological and molecular responses activated by salinity is needed to elucidate mechanisms of salinity tolerance. Transcriptome profiling (RNA-Seq) is a powerful tool to study the transcriptomic profile of genotypes under stress conditions. Persimmon species have different levels of tolerance to salinity, this variability may provide knowledge on persimmon species and development of salt--tolerant rootstocks. In this study, we conducted a physiological and transcriptomic profiling of roots and leaves in tolerant and sensitive plants of persimmon rootstock grown under saline and control conditions. Characterization of physiological responses along with gene expression changes in roots and leaves allowed the identification of several salt tolerance mechanisms related to ion transport and thermospermine synthesis. Differences were observed in putative H+/ATPases that allow transmembrane ionic...
PLOS ONE
Persimmon (Diospyros kaki Thunb.) production is facing important problems related to climate change in the Mediterranean areas. One of them is soil salinization caused by the decrease and change of the rainfall distribution. In this context, there is a need to develop cultivars adapted to the increasingly challenging soil conditions. In this study, a backcross between (D. kaki x D. virginiana) x D. kaki was conducted, to unravel the mechanism involved in salinity tolerance of persimmon. The backcross involved the two species most used as rootstock for persimmon production. Both species are clearly distinct in their level of tolerance to salinity. Variables related to growth, leaf gas exchange, leaf water relations and content of nutrients were significantly affected by saline stress in the backcross population. Water flow regulation appears as a mechanism of salt tolerance in persimmon via differences in water potential and transpiration rate, which reduces ion entrance in the plant. Genetic expression of eight putative orthologous genes involved in different mechanisms leading to salt tolerance was analyzed. Differences in expression levels among populations under saline or control treatment were found. The 'High affinity potassium transporter' (HKT1-like) reduced its expression levels in the roots in all studied populations. Results obtained allowed selection of tolerant rootstocks genotypes and describe the hypothesis about the mechanisms involved in salt tolerance in persimmon that will be useful for breeding salinity tolerant rootstocks.
Developing salt tolerant plants in a new century: A molecular biology approach
2003
Soil salinity is a major abiotic stress in plant agriculture strongly, influencing plant productivity world-wide. Classical breeding for salt tolerance in crop plants has been attempted to improve field performance without success. Therefore, an alternative strategy is to generate salt tolerant plants through genetic engineering. Several species and experimental approaches have been used in order to identify those genes that are important for salt tolerance. Due to high level of salt tolerance, halophytes are good candidates to identify salt tolerance genes. However, other species such as yeast and glycophytes have also been employed. Three approaches are commonly used to identify genes important for salt tolerance. The first approach is to identify genes involved in processes known to be critical for salt tolerance (osmolyte synthesis, ion homeostasis, etc.). The second approach is to identify genes whose expression is regulated by salt stress. This is relatively simply and applicable to any plant species. Genetic amenability of some species allows the third approach, which consists in the identification of salt tolerance determinants based on functionality. At the moment, there is a large number of reports in the literature claiming that plants with increased salt tolerance have been obtained. The main problem is that different plant species, stage of development, organs, promoters and salt conditions used it is difficult to compare the degree of salt tolerance conferred by different genes. In this review, we discuss progress made towards understanding the molecular elements involved in salt stress responses that have been used in transgenic approaches to improve salt tolerance.
Identification and characterization of a salt tolerance-responsive gene (at GRP9) of arabidopsis
Progress in Natural Science, 2003
Salinity is one of the major limitations to wheat production worldwide. This study was designed to evaluate the level of genetic variation among 150 internationally derived wheat genotypes for salinity tolerance at germination, seedling and adult plant stages, with the aim of identifying new genetic resources with desirable adaptation characteristics for breeding programmes and further genetic studies. In all the growth stages, genotype and salt treatment effects were observed. Salt stress caused 33 %, 51 % and 82 % reductions in germination vigor, seedling shoot dry matter and seed grain yield, respectively. The rate of root and shoot water loss due to salt stress exhibited significant negative correlation with shoot K + , but not with shoot Na + and shoot K + /Na + ratio. The genotypes showed a wide spectrum of response to salt stress across the growth stages; however, four genotypes, Altay2000, 14IWWYTIR-19 and UZ-11CWA-8 (tolerant) and Bobur (sensitive), exhibited consistent responses to salinity across the three growth stages. The tolerant genotypes possessed better ability to maintain stable osmotic potential, low Na + accumulation, higher shoot K + concentrations, higher rates of PSII activity, maximal photochemical efficiency and lower nonphotochemical quenching (NPQ), resulting in the significantly higher dry matter production observed under salt stress. The identified genotypes could be used as parents in breeding for new varieties with improved salt tolerance as well as in further genetic studies to uncover the genetic mechanisms governing salt stress response in wheat.
Potential Breeding Strategies for Improving Salt Tolerance in Crop Plants
Journal of Plant Growth Regulation, 2022
Salinity is one of the significant abiotic stresses that negatively affect plant production processes, growth, and development, which ultimately reduce yield. Plants adapt specific mechanisms to withstand saline conditions and activate diverse salt tolerance genes to counter osmotic and oxidative stresses induced by salinity. Genetic development in salinity tolerance is quite complex, while advancement has made less progress than expectation over the past few decades. Generating an explosion of genetics-and genomics-related information and technology in recent decades pledge to deliver innovative and advanced resources for the potential production of tolerant genotypes. Despite considerable progress in defining the primary salinity tolerance mechanisms, main obstacles are yet to be solved in the translation and incorporation of the resulting molecular knowledge into the plant breeding activities. Diverse approaches are proposed to enhance plant breeding efficacy to increase plant productivity in saline environments. Understanding the genetics of salt tolerance is a difficult task because multiple genes and pathways are involved. Important advances in tools and methods for updating and manipulating plant genomics knowledge provide detailed insights and dissect the salinity tolerance mechanism accomplished by the breeding goals. Genome-wide analyses (GWA) identify SNP variations and functional effects that appear to be the way of the future for developing salinity-tolerant plants. Gene discovery to manipulate the molecular mechanisms which underlie the complex phenotype of salinity tolerance methods, identification of genes, QTL, association mapping, linkage, and functional genomics, such as transcript identifying and proteins related to salinity, is necessary. The present analysis also discussed some of the opportunities and challenges, focusing on molecular breeding strategies used in conjunction with other crop development approaches to growing elite salt-tolerant lines.
Molecular Mechanisms of Salt Tolerance in Plants Article ID: 41060
Salinity is a significant stressor that hinders the growth and productivity of plants in many parts of the world, resulting from the increasing use of low-quality irrigation water and soil salinization. To develop salt-tolerant plant varieties for these affected areas, it is essential to have a comprehensive understanding of how plants respond to salinity stress at various levels and to integrate molecular tools with physiological and biochemical techniques. Plant adaptation or tolerance to salinity stress involves a complex interplay of physiological traits, metabolic pathways, and gene networks. Recent research has identified various adaptive responses to salinity stress at the molecular, cellular, metabolic, and physiological levels. However, the mechanisms underlying salinity tolerance are still not fully understood.
Salt-tolerant genes from halophytes are potential key players of salt tolerance in glycophytes
Environmental and Experimental Botany, 2016
Crop productivity strongly depends on several biotic and abiotic factors. Salinity is one of the most important abiotic factors, besides drought, extreme temperatures, light and metal stress. The enhanced burden of secondary salinization induced through anthropogenic activities increases pressure on glycophytic crop plants. The recent isolation and characterization of salt tolerance genes encoding signaling components from halophytes, which naturally grow in high salinity, has provided tools for the development of transgenic crop plants with improved salt tolerance and economically beneficial traits. In addition understanding of the differences between glycophytes and halophytes with respect to levels of salinity tolerance is also one of the prerequisite to achieve this goal. Based on the recent developments in mechanisms of salt tolerance in halophytes, we will explore the potential of introducing salt tolerance by choosing the available genes from both dicotyledonous and monocotyledonous halophytes, including the salt overly sensitive system (SOS)-related cation/proton antiporters of plasma (NHX/SOS1) and vacuolar membranes (NHX), energy-related pumps, such as plasma membrane and vacuolar H + adenosine triphosphatase (PM & V-H + ATPase), vacuolar H + pyrophosphatases (V-H + PPase) and potassium transporter genes. Various halophyte genes responsible for other processes, such as crosstalk signaling, osmotic solutes production and reactive oxygen species (ROS) suppression, which also enhance salt tolerance will be described. In addition, the transgenic overexpression of halophytic genes in crops (rice, peanut, finger millet, soybean, tomato, alfalfa, jatropha, etc.) will be discussed as a successful mechanism for the induction of salt tolerance. Moreover, the advances in genetic engineering technology for the production of genetically modified crops to achieve the improved salinity tolerance under field conditions will also be discussed. 2015 Elsevier B.V. All rights reserved.
Plant Physiology, 2010
To investigate early salt acclimation mechanisms in a salt-tolerant poplar species (Populus euphratica), the kinetics of molecular, metabolic, and physiological changes during a 24-h salt exposure were measured. Three distinct phases of salt stress were identified by analyses of the osmotic pressure and the shoot water potential: dehydration, salt accumulation, and osmotic restoration associated with ionic stress. The duration and intensity of these phases differed between leaves and roots. Transcriptome analysis using P. euphratica-specific microarrays revealed clusters of coexpressed genes in these phases, with only 3% overlapping salt-responsive genes in leaves and roots. Acclimation of cellular metabolism to high salt concentrations involved remodeling of amino acid and protein biosynthesis and increased expression of molecular chaperones (dehydrins, osmotin). Leaves suffered initially from dehydration, which resulted in changes in transcript levels of mitochondrial and photosynthetic genes, indicating adjustment of energy metabolism. Initially, decreases in stress-related genes were found, whereas increases occurred only when leaves had restored the osmotic balance by salt accumulation. Comparative in silico analysis of the poplar stress regulon with Arabidopsis (Arabidopsis thaliana) orthologs was used as a strategy to reduce the number of candidate genes for functional analysis. Analysis of Arabidopsis knockout lines identified a lipocalin-like gene (AtTIL) and a gene encoding a protein with previously unknown functions (AtSIS) to play roles in salt tolerance. In conclusion, by dissecting the stress transcriptome of tolerant species, novel genes important for salt endurance can be identified.
New Molecular Approaches to Improving Salt Tolerance in Crop Plants
Annals of Botany, 1998
The last century has seen enormous gains in plant productivity and in resistance to a variety of pests and diseases through much innovative plant breeding and more recently molecular engineering to prevent plant damage by insects. In contrast, improvements to salt and drought tolerance in crop and ornamental plants has been elusive, partially because they are quantitative traits and part of the multigenic responses detectable under salt\drought stress conditions. However, the rapidly expanding base of information on molecular strategies in plant adaptation to stress is likely to improve experimental strategies to achieve improved tolerance. Recently studies of salinity tolerance in crop plants have ranged from genetic mapping to molecular characterization of salt\drought induced gene products. With our increasing understanding of biochemical pathways and mechanisms that participate in plant stress responses it has also become apparent that many of these responses are common protective mechanisms that can be activated by salt, drought and cold, albeit sometimes through different signalling pathways. This review focuses on recent progress in molecular engineering to improve salt tolerance in plants in context of our current knowledge of metabolic changes elicited by salt\drought stress and the known plant characteristics useful for salt tolerance. While it is instructive to draw parallels between molecular mechanisms responsive to salt-stress with accumulating evidence from studies of related abiotic stress-responses, more data are needed to delineate those mechanisms specific for salt tolerance. Also discussed is the alternative genetic strategy that combines single-step selection of salt tolerant cells in culture, followed by regeneration of salt tolerant plants and identification of genes important in the acquired salt tolerance. Currently, transgenic plants have been used to test the effect of overexpression of specific prokaryotic or plant genes, known to be up-regulated by salt\drought stress. The incremental success of these experiments indicates a potentially useful role for these stress-induced genes in achieving long term tolerance. In addition, it is possible that enhanced expression of gene products that function in physiological systems especially sensitive to disruption by salt, could incrementally improve salt tolerance. Current knowledge points towards a need to reconcile our findings that many genes are induced by stress with the practical limitations of overexpressing all of them in a plant in a tissue specific manner that would maintain developmental control as needed. New approaches are being developed towards being able to manipulate expression of functionally related classes of genes by characterization of signalling pathways in salt\drought stress and characterization and cloning of transcription factors that regulate the expression of many genes that could contribute to salt\drought tolerance. Transcription factors that regulate functionally related genes could be particularly attractive targets for such investigations, since they may also function in regulating quantitative traits. Transgenic manipulation of such transcription factors should help us understand more about multigene regulation and its relationship to tolerance.