Analysis of Seaweed Extract-induced Transcriptome Leads to Identification of a Negative Regulator of Salt Tolerance in Arabidopsis

Successful development of plants resistant to salinity stress is problematic as a result of the complex polygenic natures of salt tolerance. Previously, alkaline extracts of the brown seaweed Ascophyllum nodosum have shown promise in enhancing plant tolerance toward abiotic stresses. To understand the underlying molecular mechanisms, the whole genome transcriptome of Arabidopsis undergoing salt stress was analyzed by microarray analysis after treatment with the chemical components of A. nodosum extracts (ANE). Treatment with ANE induced many positive regulators of salt tolerance in addition to downregulating numerous other genes. Using T-DNA insertion mutants within these downregulated genes, we examined the potential for a novel source of enhanced NaCl tolerance through removal of negative regulators of NaCl stress responses within Arabidopsis. Several potential target mutations were identified with enhanced salt-tolerant phenotypes. A T-DNA insertion within the promoter of a putative Pectin Methyl Esterase Inhibitor (PMEI) gene (At1g62760) was found to be resistant to salinity stress and was further characterized. This T-DNA insertion mutant was designated as pmei1-1. The phenotype of pmei1-1 seedlings included increased primary root growth in vitro and improved biomass accumulation under NaCl stress. Additionally, modified transcript levels of dehydration-responsive genes, including RD29A, were observed in pmei1-1 plants. Taken together, these results suggest a role for PMEI as a negative regulator of NaCl resistance and that chemical stress-induced transcriptome analysis may lead to identification of additional novel regulators of abiotic stress tolerance in plants, the use of which would have significant implications for agriculture globally.

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Low Mannitol Concentrations in Arabidopsis thaliana Expressing Ectocarpus Genes Improve Salt Tolerance

Plants ◽

10.3390/plants9111508 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1508

Author(s):

Pramod Rathor ◽

Tudor Borza ◽

Yanhui Liu ◽

Yuan Qin ◽

Sophia Stone ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Salt Tolerance ◽

Transgenic Plants ◽

Salinity Stress ◽

Stress Responses ◽

Molecular Mechanisms ◽

Ion Homeostasis ◽

Biotic And Abiotic Stress ◽

Expression Of Genes ◽

Wide Range

Mannitol is abundant in a wide range of organisms, playing important roles in biotic and abiotic stress responses. Nonetheless, mannitol is not produced by a vast majority of plants, including many important crop plants. Mannitol-producing transgenic plants displayed improved tolerance to salt stresses though mannitol production was rather low, in the µM range, compared to mM range found in plants that innately produce mannitol. Little is known about the molecular mechanisms underlying salt tolerance triggered by low concentrations of mannitol. Reported here is the production of mannitol in Arabidopsis thaliana, by expressing two mannitol biosynthesis genes from the brown alga Ectocarpus sp. strain Ec32. To date, no brown algal genes have been successfully expressed in land plants. Expression of mannitol-1-phosphate dehydrogenase and mannitol-1-phosphatase genes was associated with the production of 42.3–52.7 nmol g−1 fresh weight of mannitol, which was sufficient to impart salinity and temperature stress tolerance. Transcriptomics revealed significant differences in the expression of numerous genes, in standard and salinity stress conditions, including genes involved in K+ homeostasis, ROS signaling, plant development, photosynthesis, ABA signaling and secondary metabolism. These results suggest that the improved tolerance to salinity stress observed in transgenic plants producing mannitol in µM range is achieved by the activation of a significant number of genes, many of which are involved in priming and modulating the expression of genes involved in a variety of functions including hormone signaling, osmotic and oxidative stress, and ion homeostasis.

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A unique AtSar1D-AtRabD2a nexus modulates autophagosome biogenesis in Arabidopsis thaliana

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2021293118 ◽

2021 ◽

Vol 118 (17) ◽

pp. e2021293118

Author(s):

Yonglun Zeng ◽

Baiying Li ◽

Changyang Ji ◽

Lei Feng ◽

Fangfang Niu ◽

...

Keyword(s):

Stress Responses ◽

Higher Plants ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Secretory Proteins ◽

Insertion Mutant ◽

Intermediate Metabolites ◽

Dna Insertion ◽

Autophagy Pathway ◽

Copii Vesicles

In eukaryotes, secretory proteins traffic from the endoplasmic reticulum (ER) to the Golgi apparatus via coat protein complex II (COPII) vesicles. Intriguingly, during nutrient starvation, the COPII machinery acts constructively as a membrane source for autophagosomes during autophagy to maintain cellular homeostasis by recycling intermediate metabolites. In higher plants, essential roles of autophagy have been implicated in plant development and stress responses. Nonetheless, the membrane sources of autophagosomes, especially the participation of the COPII machinery in the autophagic pathway and autophagosome biogenesis, remains elusive in plants. Here, we provided evidence in support of a novel role of a specific Sar1 homolog AtSar1d in plant autophagy in concert with a unique Rab1/Ypt1 homolog AtRabD2a. First, proteomic analysis of the plant ATG (autophagy-related gene) interactome uncovered the mechanistic connections between ATG machinery and specific COPII components including AtSar1d and Sec23s, while a dominant negative mutant of AtSar1d exhibited distinct inhibition on YFP-ATG8 vacuolar degradation upon autophagic induction. Second, a transfer DNA insertion mutant of AtSar1d displayed starvation-related phenotypes. Third, AtSar1d regulated autophagosome progression through specific recognition of ATG8e by a noncanonical motif. Fourth, we demonstrated that a plant-unique Rab1/Ypt1 homolog AtRabD2a coordinates with AtSar1d to function as the molecular switch in mediating the COPII functions in the autophagy pathway. AtRabD2a appears to be essential for bridging the specific AtSar1d-positive COPII vesicles to the autophagy initiation complex and therefore contributes to autophagosome formation in plants. Taken together, we identified a plant-specific nexus of AtSar1d-AtRabD2a in regulating autophagosome biogenesis.

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PsrA, the Pseudomonas Sigma Regulator, Controls Regulators of Epiphytic Fitness, Quorum-Sensing Signals, and Plant Interactions in Pseudomonas syringae pv. tomato Strain DC3000

Applied and Environmental Microbiology ◽

10.1128/aem.02445-06 ◽

2007 ◽

Vol 73 (11) ◽

pp. 3684-3694 ◽

Cited By ~ 43

Author(s):

Asita Chatterjee ◽

Yaya Cui ◽

Hiroaki Hasegawa ◽

Arun K. Chatterjee

Keyword(s):

Quorum Sensing ◽

Pseudomonas Syringae ◽

Stress Responses ◽

Sigma Factor ◽

Rna Binding ◽

Negative Regulator ◽

Insertion Mutant ◽

Plant Interactions ◽

Mobility Shift ◽

Quorum Sensing Signals

ABSTRACT Pseudomonas syringae pv. tomato strain DC3000, a pathogen of tomato and Arabidopsis, occurs as an epiphyte. It produces N-acyl homoserine lactones (AHLs) which apparently function as quorum-sensing signals. A Tn5 insertion mutant of DC3000, designated PsrA− (Psr is for Pseudomonas sigma regulator), overexpresses psyR (a LuxR-type regulator of psyI) and psyI (the gene for AHL synthase), and it produces a ca. 8-fold-higher level of AHL than does DC3000. The mutant is impaired in its ability to elicit the hypersensitive reaction and is attenuated in its virulence in tomato. These phenotypes correlate with reduced expression of hrpL, the gene for an alternate sigma factor, as well as several hrp and hop genes during early stages of incubation in a Hrp-inducing medium. PsrA also positively controls rpoS, the gene for an alternate sigma factor known to control various stress responses. By contrast, PsrA negatively regulates rsmA1, an RNA-binding protein gene known to function as negative regulator, and aefR, a tetR-like gene known to control AHL production and epiphytic fitness in P. syringae pv. syringae. Gel mobility shift assays and other lines of evidence demonstrate a direct interaction of PsrA protein with rpoS promoter DNA and aefR operator DNA. In addition, PsrA negatively autoregulates and binds the psrA operator. In an AefR− mutant, the expression of psyR and psyI and AHL production are lower than those in DC3000, the AefR+ parent. In an RpoS− mutant, on the other hand, the levels of AHL and transcripts of psyR and psyI are much higher than those in the RpoS+ parent, DC3000. We present evidence, albeit indirect, that the RpoS effect occurs via psyR. Thus, AefR positively regulates AHL production, whereas RpoS has a strong negative effect. We show that AefR and RpoS do not regulate PsrA and that the PsrA effect on AHL production is exerted via its cumulative, but independent, effects on both AefR and RpoS.

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Comparative Phenotypic and Transcriptomic Analysis Reveals Key Responses of Upland Cotton to Salinity Stress During Postgermination

Frontiers in Plant Science ◽

10.3389/fpls.2021.639104 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jingxia Zhang ◽

Pei Zhang ◽

Xuehan Huo ◽

Yang Gao ◽

Yu Chen ◽

...

Keyword(s):

Salinity Stress ◽

Salinity Tolerance ◽

Molecular Mechanisms ◽

Germination Rate ◽

Primary Root ◽

Carotenoid Biosynthesis ◽

Mapk Signaling ◽

Ethylene Response Factor ◽

Sod Activity ◽

As Stress

To understand the molecular mechanisms of salinity tolerance during seed germination and post-germination stages, this study characterized phenotypic and transcriptome responses of two cotton cultivars during salinity stress. The two cultivars were salt-tolerant (ST) LMY37 and salt-sensitive (SS) ZM12, with the former exhibiting higher germination rate, growth, and primary-root fresh weight under salinity stress. Transcriptomic comparison revealed that up-regulation of differentially expressed genes (DEGs) was the main characteristic of transcriptional regulation in ST, while SS DEGs were mainly down-regulated. GO and KEGG analyses uncovered both common and specific responses in ST and SS. Common processes, such as reactive oxygen species (ROS) metabolism and cell wall biosynthesis, may be general responses to salinity in cotton. In contrast, DEGs involved in MAPK-signaling pathway activated by ROS, carotenoid biosynthesis pathway and cysteine and methionine metabolism pathway [producing the precursors of stress hormone abscisic acid (ABA) and ethylene (ET), respectively] as well as stress tolerance related transcription factor genes, showed significant expression differences between ST and SS. These differences might be the molecular basis leading to contrasting salinity tolerance. Silencing of GhERF12, an ethylene response factor gene, caused higher salinity sensitivity and increased ROS accumulation after salinity stress. In addition, peroxidase (POD) and superoxide dismutase (SOD) activity obviously declined after silencing GhERF12. These results suggest that GhERF12 is involved in salinity tolerance during early development. This study provides a novel and comprehensive perspective to understand key mechanisms of salinity tolerance and explores candidate genes that may be useful in developing stress-tolerant crops through biotechnology.

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Balancing salinity stress responses in halophytes and non-halophytes: a comparison between Thellungiella and Arabidopsis thaliana

Functional Plant Biology ◽

10.1071/fp12299 ◽

2013 ◽

Vol 40 (9) ◽

pp. 819 ◽

Cited By ~ 27

Author(s):

Dorothea Bartels ◽

Challabathula Dinakar

Keyword(s):

Arabidopsis Thaliana ◽

Salt Tolerance ◽

Salinity Tolerance ◽

Stress Responses ◽

Molecular Mechanisms ◽

Light Stress ◽

Stress Factors ◽

Natural Environments ◽

Terrestrial Plants ◽

Abiotic Stress Factors

Salinity is one of the major abiotic stress factors that drastically reduces agricultural productivity. In natural environments salinity often occurs together with other stresses such as dehydration, light stress or high temperature. Plants cope with ionic stress, dehydration and osmotic stress caused by high salinity through a variety of mechanisms at different levels involving physiological, biochemical and molecular processes. Halophytic plants exist successfully in stressful saline environments, but most of the terrestrial plants including all crop plants are glycophytes with varying levels of salt tolerance. An array of physiological, structural and biochemical adaptations in halophytes make them suitable models to study the molecular mechanisms associated with salinity tolerance. Comparative analysis of plants that differ in their abilities to tolerate salinity will aid in better understanding the phenomenon of salinity tolerance. The halophyte Thellungiella salsuginea has been used as a model for studying plant salt tolerance. In this review, T. salsuginea and the glycophyte Arabidopsis thaliana are compared with regards to their biochemical, physiological and molecular responses to salinity. In addition recent developments are presented for improvement of salinity tolerance in glycophytic plants using genes from halophytes.

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Transcriptome Analysis of Salt Stress Response in Roots of Halophyte Zoysia macrostachya

International Journal of Agriculture and Biology ◽

10.17957/ijab/15.1705 ◽

2021 ◽

Vol 25 (03) ◽

pp. 591-600

Author(s):

Huaguang Hu

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Transcriptome Analysis ◽

Molecular Mechanisms ◽

Expression Profiles ◽

Transcript Abundance ◽

Nacl Stress ◽

Ros Scavenging ◽

Salt Stress Response ◽

Sequencing Platform

Zoysia macrostachya Franch. et Sav. is a halophyte with very strong tolerance to salinity, which can serve as an alternative turfgrass for landscaping in saline-alkali land and provide the salt-tolerance genes for turfgrass breeding. To further illustrate the salt-tolerance mechanisms in this species at molecular level, the roots transcriptome of Z. macrostachya was investigated under salt stress using the Illumina sequencing platform. Altogether 47,325 unigenes were assembled, among which, 32,542 (68.76%) were annotated, and 87.61% clean reads were mapped to the unigenes. Specifically, 14,558 unigenes were shown to be the differentially expressed genes (DEGs) following exposure to 710 mM NaCl stress compared with control, including 7972 up-regulated and 6586 down-regulated DEGs. Among these DEGs, 24 were associated with the reactive oxygen species (ROS) scavenging system, 61 were found to be related to K+ and Na+ transportation, and 16 were related to the metabolism of osmotic adjustment substances. Additionally, 2327 DEGs that encoded the transcription factors (TFs) were also identified. The expression profiles for 10 DEGs examined through quantitative real-time PCR conformed to the individual alterations of transcript abundance verified through RNA-Seq. Taken together, results of transcriptome analysis in this study provided useful insights for salt-tolerance molecular mechanisms of Z. macrostachya. Furthermore, these DEGs under salt stress provided important clues for future salt-tolerance genes cloning of Z. macrostachya. © 2021 Friends Science Publishers

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CRK2 enhances salt tolerance in Arabidopsis thaliana by regulating endocytosis and callose deposition in connection with PLDα1

10.1101/487009 ◽

2018 ◽

Cited By ~ 1

Author(s):

Kerri Hunter ◽

Sachie Kimura ◽

Anne Rokka ◽

Cuong Tran ◽

Masatsugu Toyota ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Salt Stress ◽

Salt Tolerance ◽

Subcellular Localization ◽

Stress Responses ◽

Negative Regulator ◽

Biotic And Abiotic Stress ◽

Callose Deposition ◽

Receptor Like Kinase ◽

Stress Dependent

AbstractHigh salinity has become an increasingly prevalent source of stress to which plants need to adapt. The receptor-like protein kinases (RLKs), including the cysteine-rich receptor-like kinase (CRK) subfamily, are a highly expanded family of transmembrane proteins in plants and are largely responsible for communication between cells and the extracellular environment. Various CRKs have been implicated in biotic and abiotic stress responses, however their functions on a cellular level remain largely uncharacterized. Here we have shown that CRK2 enhances salt tolerance at the germination stage in Arabidopsis thaliana. We identified CRK2 as a negative regulator of endocytosis, under both normal growth conditions and salt stress. We also established that functional CRK2 is required for salt-induced callose deposition. In doing so, we revealed a novel role for callose deposition, in response to increased salinity, and demonstrated its importance for salt tolerance during germination. Using fluorescently tagged proteins we observed specific changes in CRK2’s subcellular localization in response to various stress treatments. Many of CRK2’s cellular functions were dependent on phospholipase D (PLD) activity, as were the subcellular localization changes. Thus we propose that CRK2 acts downstream of PLD during salt stress to regulate endocytosis and promote callose deposition, and that CRK2 adopts specific stress-dependent subcellular localization patterns in order to carry out its functions.One sentence summaryThe receptor-like kinase CRK2 acts in connection with PLDα1 to regulate endocytosis and callose deposition at plasmodesmata, enhancing salt tolerance in Arabidopsis thaliana.

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Plant ionic relation and whole-plant physiological responses to waterlogging, salinity and their combination in barley

Functional Plant Biology ◽

10.1071/fp16385 ◽

2017 ◽

Vol 44 (9) ◽

pp. 941 ◽

Cited By ~ 8

Author(s):

Zhinous Falakboland ◽

Meixue Zhou ◽

Fanrong Zeng ◽

Ali Kiani-Pouya ◽

Lana Shabala ◽

...

Keyword(s):

Stress Tolerance ◽

Salinity Stress ◽

Molecular Mechanisms ◽

Photochemical Efficiency ◽

Damage Index ◽

Nacl Stress ◽

Plant Performance ◽

Combined Stress ◽

Salinity Stress Tolerance ◽

Stress Damage

Waterlogging and salinity stresses significantly affect crop growth and global food production, and these stresses are often interrelated because waterlogging can lead to land salinisation by transporting salts to the surface. Although the physiological and molecular mechanisms of plant responses to each of these environmental constraints have been studied in detail, fewer studies have dealt with potential mechanisms underlying plant tolerance to the combined stress. This gap in knowledge is jeopardising the success of breeding programs. In the present work we studied the physiological and agronomical responses of 12 barley varieties contrasting in salinity stress tolerance to waterlogging (WL), salinity (NaCl) and combined (WL/NaCl) stresses. Stress damage symptoms were much greater in plants under combined WL/NaCl stress than those under separate stresses. The shoot biomass, chlorophyll content, maximum photochemical efficiency of PSII and shoot K+ concentration were significantly reduced under WL/NaCl conditions, whereas shoot Na+ concentration increased. Plants exposed to salinity stress showed lower damage indexes compared with WL. Chlorophyll fluorescence Fv/Fm value showed the highest correlation with the stress damage index under WL/NaCl conditions (r = –0.751) compared with other measured physiological traits, so was nominated as a good parameter to rank the tolerance of varieties. Average FW was reduced to 73 ± 2, 52 ± 1 and 23 ± 2 percent of the control under NaCl, WL and combined WL/NaCl treatments respectively. Generally, the adverse effect of WL/NaCl stress was much greater in salt-sensitive varieties than in more tolerant varieties. Na+ concentrations of the shoot under control conditions were 97 ± 10 µmol g–1 DW, and increased to 1519 ± 123, 179 ± 11 and 2733 ± 248 µmol g–1 under NaCl, WL and combined WL/NaCl stresses respectively. K+ concentrations were 1378 ± 66, 1260 ± 74, 1270 ± 79 and 411 ± 92 µmol g–1 DW under control, NaCl, WL and combined WL/NaCl stresses respectively. No significant correlation was found between the overall salinity stress tolerance and amount of Na+ accumulated in plant shoots after 15 days of exposure to 250 mM NaCl stress. However, plants exposed to combined salinity and WL stress showed a negative correlation between shoot Na+ accumulation and extent of salinity damage. Overall, the reported results indicate that K+ reduction in the plants under combined WL/NaCl stress, but not stress-induced Na+ accumulation in the shoot, was the most critical feature in determining the overall plant performance under combined stress conditions.

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Seed biostimulant Bacillus sp. MGW9 improves the salt tolerance of maize during seed germination

AMB Express ◽

10.1186/s13568-021-01237-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Heqin Li ◽

Haiwang Yue ◽

Li Li ◽

Yu Liu ◽

Haiyan Zhang ◽

...

Keyword(s):

Salt Tolerance ◽

Seed Germination ◽

Salinity Stress ◽

Sugar Content ◽

Soluble Sugar ◽

Primary Root ◽

Dry Weight ◽

Fresh Weight ◽

Acetic Acid Production ◽

Seed Biopriming

AbstractCrop performance is seriously affected by high salt concentrations in soils. To develop improved seed pre-sowing treatment technologies, it is crucial to improve the salt tolerance of seed germination. Here, we isolated and identified the strain Bacillus sp. MGW9 and developed the seed biostimulant MGW9. The effects of seed biopriming with the seed biostimulant MGW9 in maize (Zea mays L.) under saline conditions were studied. The results show that the strain Bacillus sp. MGW9 has characteristics such as salt tolerance, nitrogen fixation, phosphorus dissolution, and indole-3-acetic acid production. Seed biopriming with the seed biostimulant MGW9 enhanced the performance of maize during seed germination under salinity stress, improving the germination energy, germination percentage, shoot/seedling length, primary root length, shoot/seedling fresh weight, shoot/seedling dry weight, root fresh weight and root dry weight. Seed biostimulant MGW9 biopriming also alleviated the salinity damage to maize by improving the relative water content, chlorophyll content, proline content, soluble sugar content, root activity, and activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, while decreasing the malondialdehyde content. In particular, the field seedling emergence of maize seeds in saline-alkali soil can be improved by biopriming with the seed biostimulant MGW9. Therefore, maize seed biopriming with the seed biostimulant MGW9 could be an effective approach to overcoming the inhibitory effects of salinity stress and promoting seed germination and seedling growth.

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Improved salt tolerance in transgenic tobacco by over-expression of poplar NAC13 gene

10.7287/peerj.preprints.27861 ◽

2019 ◽

Author(s):

Xuemei Zhang ◽

Zihan Cheng ◽

Kai Zhao ◽

Renhua Li ◽

Boru Zhou ◽

...

Keyword(s):

Transcription Factor ◽

Salt Stress ◽

Salt Tolerance ◽

Transgenic Tobacco ◽

Stress Responses ◽

Gene Networks ◽

Molecular Mechanisms ◽

Physiological Characterization ◽

Protein Functions ◽

Forest Genetic

Background: NACs are one of the major transcription factor families in plants which play an important role in plant growth and development, as well as in adverse stress responses. Methods: In this study, we cloned a salt-inducible NAC transcription factor gene (NAC13) from a poplar variety 84K, followed by transforming it into both tobacco and Arabidopsis. Results: Stable expression analysis of 35S::NAC13-GFP fusion protein in Arabidopsis indicated that NAC13 was localized to the nucleus. We also obtained five transgenic tobacco lines. Evidence from morphological and physiological characterization and salt treatment analyses indicated that the transgenic tobacco enhanced salt tolerance, suggesting that NAC13 gene may function as a positive regulator in tobacco responses to salt stress. Furthermore, evidence from yeast two-hybrid screening demonstrated that NAC13 protein functions as a transcriptional activator, with an activation domain located in the C-terminal region. Discussion: NAC13 gene plays an important role in response to salt stress in tobacco. Future studies are needed to shed light on molecular mechanisms of gene regulation and gene networks related to NAC13 gene in response to salt stress, which will provide a valuable theoretical basis for forest genetic breeding and resistant breeding.

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