Stress Tolerance In Plant Species Research Articles

Pectin demethylation-mediated cell wall Na+ retention positively regulates salt stress tolerance in oilseed rape.

Integrated phenomics, ionomics, genomics, transcriptomics, and functional analyses present novel insights into the role of pectin demethylation-mediated cell wall Na+ retention in positively regulating salt tolerance in oilseed rape. Genetic variations in salt stress tolerance identified in rapeseed genotypes highlight the complicated regulatory mechanisms. Westar is ubiquitously used as a transgenic receptor cultivar, while ZS11 is widely grown as a high-production and good-quality cultivar. In this study, Westar was found to outperform ZS11 under salt stress. Through cell component isolation, non-invasive micro-test, X-ray energy spectrum analysis, and ionomic profile characterization, pectin demethylation-mediated cell wall Na+ retention was proposed to be a major regulator responsible for differential salt tolerance between Westar and ZS11. Integrated analyses of genome-wide DNA variations, differential expression profiling, and gene co-expression networks identified BnaC9.PME47, encoding a pectin methylesterase, as a positive regulator conferring salt tolerance in rapeseed. BnaC9.PME47, located in two reported QTL regions for salt tolerance, was strongly induced by salt stress and localized on the cell wall. Natural variation of the promoter regions conferred higher expression of BnaC9.PME47 in Westar than in several salt-sensitive rapeseed genotypes. Loss of function of AtPME47 resulted in the hypersensitivity of Arabidopsis plants to salt stress. The integrated multiomics analyses revealed novel insights into pectin demethylation-mediated cell wall Na+ retention in regulating differential salt tolerance in allotetraploid rapeseed genotypes. Furthermore, these analyses have provided key information regarding the rapid dissection of quantitative trait genes responsible for nutrient stress tolerance in plant species with complex genomes.

Morphology, photosynthetic physiology and biochemistry of nine herbaceous plants under water stress.

Global climate warming and shifts in rainfall patterns are expected to trigger increases in the frequency and magnitude of drought and/or waterlogging stress in plants. To cope with water stress, plants develop diverse tactics. However, the adoption capability and mechanism vary depending upon the plant species identity as well as stress duration and intensity. The objectives of this study were to evaluate the species-dependent responses of alpine herbaceous species to water stress. Nine herbaceous species were subjected to different water stresses (including moderate drought and moderate waterlogging) in pot culture using a randomized complete block design with three replications for each treatment. We hypothesized that water stress would negatively impact plant growth and metabolism. We found considerable interspecies differences in morphological, physiological, and biochemical responses when plants were exposed to the same water regime. In addition, we observed pronounced interactive effects of water regime and plant species identity on plant height, root length, root/shoot ratio, biomass, and contents of chlorophyll a, chlorophyll b, chlorophyll (a+b), carotenoids, malondialdehyde, soluble sugar, betaine, soluble protein and proline, implying that plants respond to water regime differently. Our findings may cast new light on the ecological restoration of grasslands and wetlands in the Qinghai-Tibetan Plateau by helping to select stress-tolerant plant species.

Photochemical analysis for selection of stress tolerant plant

This electronic document is a “live” template and already defin This study was carried out to selection of abiotic stress tolerant plant species of sixty-eight plant species at Hantaek Botanical Garden in Korean using photochemical analysis. Many abiotic stresses have led to a decline in agricultural productivity and the disappearance of ecologically important plant species. Chlorophyll a fluorescence is a powerful tool to measure environmental stress response in plants. The polyphasic OJIP fluorescence transient was used to evaluate the behavior of Photosystem II (PSII) and Photosystem I (PSI) during the entire experiment period (from July to August). The photochemical reaction showed higher maximal chlorophyll fluorescence (Fp) intensity under heat and wet stress in forty-one plant species. In twenty seven plant species, chlorophyll fluorescence intensity showed a significant decrease.
 In wet stress, the fluorescence parameters related with electron transport on PSII and PSI reduced over twenty percent. As a result of the identifying under heat and wet stress, energy dissipation per reaction center (DIo/RC) was heavily affected.
 It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective in the selection of stress tolerant plants.

Fly-Ash Pollution Modulates Growth, Biochemical Attributes, Antioxidant Activity and Gene Expression in Pithecellobium Dulce (Roxb) Benth.

This study investigates the effect of fly ash (FA) on the Pithecellobium dulce (Roxb) Benth. trees growing at three different locations. FA stress caused significant changes in different leaf attributes like sugar, protein contents, photosynthetic pigments, nitrate content and nitrate reductase activity in foliar tissues of plants growing at a highly contaminated site, as compared to a low-pollution site. Lower rates of stomatal conductance (SC) were observed in P. dulce leaves under fly ash stress conditions that drastically reduced net photosynthetic rate (PN); however, intercellular carbon dioxide concentration and stomatal index (SI) showed an increase under the same stress conditions. On the other hand, significant increase was also observed in the proline, sulphur and nitrogen contents. A significant increase in oxidative stress and, consequently, in antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxidase dismutase (SOD) and Air pollution tolerance index were discovered at three different sites. The transcriptional expression of antioxidant and stress responsive genes was higher at HPS as compared to two other two sites of the study. Taken together the results demonstrated that the P. dulce is best suited as a fly ash stress tolerant plant species with the potential to provide an alternative for the reclamation of fly ash affected soils.

Mycorrhizal features and leaf traits covary at the community level during primary succession

Abstract The mycorrhizal association between fungi and plants is thought to be an important component of the functional diversity of plant communities, although evidence is weak. We explored community-level changes to mycorrhizal features and leaf traits along a primary successional gradient on a sedimentation coast. We found that community weighted mean values of mycorrhizal features and leaf traits varied systematically along the successional series, representing a transition from communities dominated by more stress-tolerant plant species (less mycorrhizal colonization and lower specific leaf area) to less stress-tolerant plant species (higher mycorrhizal colonization and specific leaf area). Despite the co-variation in leaf traits and mycorrhizal features at the community level, only mycorrhizal features showed an increasing functional diversity with successional age. These results suggest that mycorrhizal fungi should not be forgotten in trait-based plant community ecology.

The hydrogen sulfide, a downstream signaling molecule of hydrogen peroxide and nitric oxide, involves spermidine-regulated transcription factors and antioxidant defense in white clover in response to dehydration

Hydrogen sulfide (H2S) nowadays is regarded as a novel gaseous signaling molecule in plants during environmental stress response. The spermidine (Spd), an important plant growth regulator, plays critical roles in regulating stress tolerance in plant species. Objectives of this study were to examine whether Spd could act as a H2S signaling activator to regulate stress-responsive transcription factors (TFs) and antioxidant defense and to further explore the possible crosstalk among Spd-induced hydrogen peroxide (H2O2), nitric oxide (NO), and H2S signaling in leaves of white clover. Results showed that dehydration or exogenous application of Spd could significantly increase L/D-cysteine desulfhydrate (L/DCD) activities and then cause a quick accumulation of H2S, followed by significant improvement of antioxidant enzyme (SOD, CAT, GPOX, APX, GR, DHAR, and MDHAR) activities and transcript levels of TFs (bZIP37, bZIP107, DREB2, DREB4, and WRKY108715) and genes encoding antioxidant enzymes. The inhibitors (AOA and NH2OH) of L/DCD activities could effectively attenuate dehydration- or Spd-induced these effects in leaves. Additionally, dehydration-induced increase in H2S accumulation, L/DCD and antioxidant enzyme activities, and genes expression were remarkably abolished by the application of Spd biosynthesis inhibitor (DCHA), whereas exogenous Spd significantly alleviate the inhibitory effect of DCHA on these parameters under dehydration condition. This indicated that H2S which was derived from L/DCD pathway might act as a downstream signaling of Spd, and Spd-activated H2S signaling was involved in dehydration-regulated TFs and antioxidant defense associated with dehydration tolerance. Further analyses found that Spd-induced H2O2 production could not be attenuated by scavengers of NO and H2S, but the scavenger of H2O2 effectively inhibited Spd-induced increases in NO and H2S. The Spd-induced H2S signaling was also substantially inhibited by the application of the NO scavenger. The result implied that Spd-induced H2O2 could be an upstream signal molecule of NO and H2S, and the Spd-induced H2S might act as the downstream signaling of NO in leaves. These obtained results provide the basic evidence to understand Spd-regulated signal transduction in white clover.

Structural and functional characteristics of buffer strip vegetation in an agricultural landscape – high potential for nutrient removal but low potential for plant biodiversity

Vegetated buffer strips constitute a transition zone between terrestrial and aquatic ecosystems and provide several ecosystem services. Buffer strips are often applied as a mitigation measure against diffuse pollution in agricultural areas, primarily because they may retain nutrients and in this way help protect the aquatic environment. Additionally, they can improve biodiversity in an otherwise homogenous landscape and may therefore have a value in their own right. In the present study, we characterized the structural and functional features of the vegetation in Danish buffer strips using a nationwide dataset to explore: i) their floristic quality in terms of species diversity and conservation value and ii) based on their functional characteristics, their potential to retain nutrients. Moreover, we analyzed how the structural and functional characteristics varied along gradients in the environmental features of the catchment. We found that the floristic quality of the buffer vegetation was generally low, exhibiting an average of only 3.3% of the number of species of conservation interest. Instead, Danish buffer strips were dominated by widespread and productive species that are tolerant of anthropogenic impacts in the catchment. The abundance of highly productive plant species was positively related to high intensity land use, whereas the abundance of stress-tolerant plant species was positively related to low intensity land use. The high productivity of the buffer strips implies a large bio-storage potential, and these areas might therefore offer an opportunity to remove nutrients by harvesting the plant biomass. We discuss how Danish buffer strips could be exploited via appropriate management (e.g. harvesting) to maximize nutrient retention and at the same time improve floristic quality.

The membrane tethered transcription factor EcbZIP17 from finger millet promotes plant growth and enhances tolerance to abiotic stresses

The occurrence of various stresses, as the outcome of global climate change, results in the yield losses of crop plants. Prospecting of genes in stress tolerant plant species may help to protect and improve their agronomic performance. Finger millet (Eleusine coracana L.) is a valuable source of superior genes and alleles for stress tolerance. In this study, we isolated a novel endoplasmic reticulum (ER) membrane tethered bZIP transcription factor from finger millet, EcbZIP17. Transgenic tobacco plants overexpressing this gene showed better vegetative growth and seed yield compared with wild type (WT) plants under optimal growth conditions and confirmed upregulation of brassinosteroid signalling genes. Under various abiotic stresses, such as 250 mM NaCl, 10% PEG6000, 400 mM mannitol, water withdrawal, and heat stress, the transgenic plants showed higher germination rate, biomass, primary and secondary root formation, and recovery rate, compared with WT plants. The transgenic plants exposed to an ER stress inducer resulted in greater leaf diameter and plant height as well as higher expression of the ER stress-responsive genes BiP, PDIL, and CRT1. Overall, our results indicated that EcbZIP17 improves plant growth at optimal conditions through brassinosteroid signalling and provide tolerance to various environmental stresses via ER signalling pathways.

Genome-wide sequential, evolutionary, organizational and expression analyses of phenylpropanoid biosynthesis associated MYB domain transcription factors in Arabidopsis

The MYB gene family represents one of the largest groups of transcription factors in plants. Recent evidences have also demonstrated key role of MYB transcription factors in regulating the expression of major genes involved in the biosynthesis of phenylpropanoid compounds which confer biotic and abiotic stress tolerance in plant species. However, no comprehensive genome-wide analysis of the phenylpropanoid pathway-associated MYB transcription factors has been reported thus far. In this study, 11 Arabidopsis MYB proteins, such as MYB3, MYB4, MYB7, MYB11, MYB12, MYB32, MYB75, MYB90, MYB111, MYB113, and MYB114 were initially identified considering their reported regulatory function in phenylpropanoid biosynthesis pathway. Subsequent genome-wide analysis have identified the corresponding homologues from Glycine max, Vigna radiata, Oryza sativa, and Zea mays, while homologous of Arabidopsis MYB75, MYB90, MYB113, and MYB114 were not detected in rice and maize genomes. The identified MYB proteins were classified into three groups (I-III) based on phylogeny. Sequence and domain analysis revealed presence of two conserved DNA binding MYB domains in the selected MYB proteins. Promoter analysis indicated presence of cis-regulatory elements related to light signaling, development, and stress response. Expression analysis of selected Arabidopsis MYB genes revealed their function in plant development and abiotic stress response, consistent with gene ontology annotations. Together, these results provide a useful framework for further experimental studies for the functional characterization of the target MYB genes in the context of regulation of phenylpropanoid biosynthesis and plant stress response.

Stilbene accumulation and expression of stilbene biosynthesis pathway genes in wild grapevine Vitis amurensis Rupr.

We detected and quantified six stilbenes ( cis -piceid, t -piceid, t -ε-viniferin, cis -ε-viniferin, t -resveratrol, and t -δ-viniferin) in the leaves, petioles, berry skins, and seeds of wild-growing Vitis amurensis . The highest content of stilbenes and expression of stilbene biosynthesis genes were in the probes collected in the autumn and after ultraviolet elicitation. Stilbenes, including the best-studied stilbene resveratrol, are known to display valuable bioactivities and protect plants against various pathogens. There is a lack of studies on stilbene quantities and spectrum combined with an analysis of the stilbene biosynthesis pathway gene expression in Vitaceae species, despite grapevine is an important source of stilbenes. This study presents an analysis of stilbene spectrum, stilbene content, and expression of stilbene biosynthesis genes both in natural conditions and after ultraviolet (UV-C) elicitation in the leaves, petioles, berry skins, and seeds of wild-growing Vitis amurensis, a highly stress-tolerant plant species. Using HPLC analysis, we detected six main stilbenes: cis-piceid (up to 0.257mg/g of dry weight (DW) of plant material), t-piceid (up to 0.055mg/g DW), t-ε-viniferin (up to 0.122mg/g DW), cis-ε-viniferin (up to 0.031mg/g DW), t-resveratrol (from 0.004 to 0.121mg/g DW), and t-δ-viniferin (up to 0.019mg/g DW). The stilbenes were actively synthesized in the leaves (total stilbenes 0.39mg/g DW) and berry skins (total stilbenes 0.249mg/g DW) of V. amurensis collected in the autumn. qRT-PCR revealed that the stilbene synthase (STS), resveratrol O-glucosyltransferase (Glu1), and polyphenol oxidase (PPO1) genes were actively expressed in the analyzed tissues. The resveratrol methyltransferase (Romt1) gene, which is known to catalyze biosynthesis of pterostilbene, was also expressed, but no pterostilbene has been detected in V. amurensis. The content of all detected stilbenes and expression of stilbene biosynthesis genes increased after UV-C treatment, except for Romt1. The data are important for understanding the stilbene biosynthesis in grapevine.

Analysis of bHLH coding genes using gene co-expression network approach.

Network analysis provides a powerful framework for the interpretation of data. It uses novel reference network-based metrices for module evolution. These could be used to identify module of highly connected genes showing variation in co-expression network. In this study, a co-expression network-based approach was used for analyzing the genes from microarray data. Our approach consists of a simple but robust rank-based network construction. The publicly available gene expression data of Solanum tuberosum under cold and heat stresses were considered to create and analyze a gene co-expression network. The analysis provide highly co-expressed module of bHLH coding genes based on correlation values. Our approach was to analyze the variation of genes expression, according to the time period of stress through co-expression network approach. As the result, the seed genes were identified showing multiple connections with other genes in the samecluster. Seed genes were found to be vary in different time periods of stress. These analyzed seed genes may be utilized further as marker genes for developing the stress tolerant plant species.

Plastid Terminal Oxidase as a Route to Improving Plant Stress Tolerance: Known Knowns and Known Unknowns.

A plastid-localized terminal oxidase, PTox, was first described due to its role in chloroplast development, with plants lacking PTox producing white sectors on their leaves. This phenotype is explained as being due to PTox playing a role in carotenoid biosynthesis, as a cofactor of phytoene desaturase. Co-occurrence of PTox with a chloroplast-localized NADPH dehydrogenase (NDH) has suggested the possibility of a functional respiratory pathway in plastids. Evidence has also been found that, in certain stress-tolerant plant species, PTox can act as an electron acceptor from PSII, making it a candidate for engineering stress-tolerant crops. However, attempts to induce such a pathway via overexpression of the PTox protein have failed to date. Here we review the current understanding of PTox function in higher plants and discuss possible barriers to inducing PTox activity to improve stress tolerance.

Saltgrass, a Minimum Water and Nutrient Requirement Halophytic Plant Species for Sustainable Agriculture in Desert Regions

Context: Desertification of arable lands due to global warming and water shortage mandates use of low-quality water for irrigation. Using low-quality water imposes more stress on plants which are already under stress. Thus, there is an urgent need for finding stress tolerant plant species to survive/sustain under such stressful conditions. Since the native plants are already growing under such conditions and are adapted to these stresses, they are the most suitable candidates to be manipulated under the minimum cultural practices and minimum inputs for use under stress. If stress tolerant species/genotypes of the native plants are identified, there would be a substantial savings in cultural practices and inputs in using them. Aim: This grass has multi usages, including animal feed, soil conservation, saline soils reclamation, use in desert landscaping, and combating desertification. The objectives of this study were to find the most salinity and drought tolerant of various saltgrass genotypes for use in arid regions, where limited water supplies coupled with saline soils result in drought and salinity stresses. Materials and Methods: Various genotypes of saltgrass were studied in a greenhouse either hydroponically in culture solution for salt tolerance or in large galvanized cans contained fritted clay for drought tolerance. For the salinity stress tolerance, twelve inland saltgrass clones were studied in a greenhouse, using hydroponics technique to evaluate their growth responses under salt stress. Four salt treatments (EC 6, 20, 34, and 48 dS/m salinity stress) were replicated 3 times in a randomized complete block design experiment. Grasses were grown under these conditions for 10 weeks. During this period, shoots were clipped bi-weekly, clippings were oven dried at 75°C and dry matter (DM) weights were recorded, shoot and root lengths were also measured. At the last harvest, roots were also harvested, oven dried, and DM weights were determined. Grass quality was weekly evaluated and recorded. Although all the grasses showed a high level of salinity tolerance, there was a wide range of variations observed in salt tolerance of these saltgrass clones. For the drought tolerance study, 21 saltgrass clones were studied to evaluate their growth responses under drought stress. Plants were grown under normal condition for 6 months for complete establishment. Then, they were deprived from water for 4 months. Plant shoots were harvested weekly and oven dried at 75°C for DM weight determination. At each harvest, percentages of plant green covers were also estimated and recorded. Both the shoot dry weights and the percent of plant visual green cover decreased as drought period progressed. Results: Although all the grasses exhibited a high level of drought tolerance, there was a wide range of variations observed in various clones' responses. The superior salinity and drought stress tolerant genotypes were identified to be used for biological salinity control or reclamation of desert saline soils and combating desertification. Conclusion: My investigations at the University of Arizona on saltgrass (Distichlis spicata L.), a halophytic plant species, have indicated that this plant has an excellent drought and salinity tolerance with a great potential to be used under harsh environmental conditions.

Genome-wide identification of galactinol synthase (GolS) genes in Solanum lycopersicum and Brachypodium distachyon

GolS genes stand as potential candidate genes for molecular breeding and/or engineering programs in order for improving abiotic stress tolerance in plant species. In this study, a total of six galactinol synthase (GolS) genes/proteins were retrieved for Solanum lycopersicum and Brachypodium distachyon. GolS protein sequences were identified to include glyco_transf_8 (PF01501) domain structure, and to have a close molecular weight (36.40–39.59kDa) and amino acid length (318–347 aa) with a slightly acidic pI (5.35–6.40). The sub-cellular location was mainly predicted as cytoplasmic. S. lycopersicum genes located on chr 1 and 2, and included one segmental duplication while genes of B. distachyon were only on chr 1 with one tandem duplication. GolS sequences were found to have well conserved motif structures. Cis-acting analysis was performed for three abiotic stress responsive elements, including ABA responsive element (ABRE), dehydration and cold responsive elements (DRE/CRT) and low-temperature responsive element (LTRE). ABRE elements were found in all GolS genes, except for SlGolS4; DRE/CRT was not detected in any GolS genes and LTRE element found in SlGolS1 and BdGolS1 genes. AU analysis in UTR and ORF regions indicated that SlGolS and BdGolS mRNAs may have a short half-life. SlGolS3 and SlGolS4 genes may generate more stable transcripts since they included AATTAAA motif for polyadenylation signal POLASIG2. Seconder structures of SlGolS proteins were well conserved than that of BdGolS. Some structural divergences were detected in 3D structures and predicted binding sites exhibited various patterns in GolS proteins.

A sucrose:fructan-6-fructosyltransferase (6-SFT) gene from Psathyrostachys huashanica confers abiotic stress tolerance in tobacco

Fructans are accessible carbohydrate reserves in various plant species, which possess many physiological functions including anti-oxidation, stabilizing subcellular structures, and osmotic adjustment. In addition, fructans may play important roles in stress tolerance in plant species. In this study, we isolated a Psathyrostachys huashanica (2n=2x=14, NsNs) sucrose:fructan-6-fructosyltransferase (Ph-6-SFT) using homologous cloning and genomic walking. Sequencing and gene structure analysis showed that Ph-6-SFT contains four exons and three introns, with a transcript of 2207bp. Sequence analysis indicated that the coding sequence of Ph-6-SFT is 1851bp long and it encodes 616 amino acids, where the structure shares high similarity with 6-SFTs from other plants. Furthermore, Ph-6-SFT was transferred into tobacco (Nicotiana tabacum L.) cv. W38 via Agrobacterium-mediated transformation. Compared with the wild-type plants, the transgenic tobacco plants exhibited a much higher tolerance of drought, cold, and high salinity. In all conditions, physiological studies showed that the tolerance of transgenic plants was associated with the accumulation of carbohydrate and proline, but reductions in malondialdehyde. Our results suggest that the 6-SFT gene from P. huashanica enhanced stress tolerance in tobacco plants and it may be applied as a genetic tool for improving stress tolerance in other crops.

Stress tolerant plant species spread in the road-net

Roads are known for being corridors for not only migration of small animals, but also expansive, invasive and halophytic plants. At least sixteen wildly growing halophytes and many other salt-tolerant species were found along various types of roads in the Czech Republic. The most halophytes belonged to the families of Poaceae (23%) and Asteraceae (20%). Since many plants growing along roads are weeds, there is a real danger that these plants will invade nearby agricultural crops. Thus biological degradation of agricultural areas can be started.

Stress tolerant plant species spread in the road-net

Roads are known for being corridors for not only migration of small animals, but also expansive, invasive and halophytic plants. At least sixteen wildly growing halophytes and many other salt-tolerant species were found along various types of roads in the Czech Republic. The most halophytes belonged to the families of Poaceae (23%) and Asteraceae (20%). Since many plants growing along roads are weeds, there is a real danger that these plants will invade nearby agricultural crops. Thus biological degradation of agricultural areas can be started.

The Association Among Gene Expression Responses to Nine Abiotic Stress Treatments in Arabidopsis thaliana

The identification and analysis of genes exhibiting large expression responses to several different types of stress may provide insights into the functional basis of multiple stress tolerance in plant species. This study considered whole-genome transcriptional profiles from Arabidopsis thaliana root and shoot organs under nine abiotic stress conditions (cold, osmotic stress, salt, drought, genotoxic stress, ultraviolet light, oxidative stress, wounding, and high temperature) and at six different time points of stress exposure (0.5, 1, 3, 6, 12, and 24 hr). In roots, genomewide correlations between transcriptional responses to different stress treatments peaked following 1 hr of stress exposure, while in shoots, correlations tended to increase following 6 hr of stress exposure. The generality of stress responses at the transcriptional level was therefore time and organ dependent. A total of 67 genes were identified as exhibiting a statistically significant pattern of gene expression characterized by large transcriptional responses to all nine stress treatments. Most genes were identified from early to middle (1-6 hr) time points of stress exposure. Analysis of this gene set indicated that cell rescue/defense/virulence, energy, and metabolism functional classes were overrepresented, providing novel insight into the functional basis of multiple stress tolerance in Arabidopsis.

Evaluation of environmental stress-tolerance in barley varieties by capillary electrophoresis

Varieties of barley were cultured with and without drought stress and an osmoregulatory cellu- lar component, glycine betaine, was determined by capillary electrophoresis. The relation between the betaine levels and stress-tolerance in the varieties was surveyed. The salt stress-tol- erant and -sensitive varieties were well discriminated by the betaine levels in the seedlings of bar- ley cultured under stressed and unstressed conditions. Also, the betaine levels could discrimi- nate between African and Japanese varieties, presumably due to the climate difference between the two areas. It was found that glycine betaine is a good candidate as a probe in selecting envi- ronmental stress-tolerant plant species.

Genetic engineering of polyamine and carbohydrate metabolism for osmotic stress tolerance in higher plants

Plant growth and productivity are greatly affected by various stress factors. The molecular mechanisms of stress tolerance in plant species have been well established. Metabolic pathways involving the synthesis of metabolites such as polyamines, carbohydrates, proline and glycine betaine have been shown to be associated with stress tolerance. Introduction of the stress-induced genes involved in these pathways from tolerant species to sensitive plants seems to be a promising approach to confer stress tolerance in plants. In cases where single gene is not enough to confer tolerance, metabolic engineering necessitates the introduction of multiple transgenes in plants.