Salt Adaptation Mechanisms Research Articles

Lipid metabolism improves salt tolerance of Salicornia europaea.

Salicornia europaea L., a succulent euhalophyte plant, has been found to exhibit optimal reproductive capabilities under appropriate salinity concentrations. However, the underlying metabolic changes are not yet fully understood. This study conducted a comprehensive analysis combining transcriptomic and lipidomic techniques to investigate the molecular mechanisms of lipid metabolism in response to different NaCl concentrations (0 and 200mM). Transcriptomic data demonstrated that salt treatment mainly affected processes including lipid biosynthesis, phosphatidylinositol signaling, and glycerophospholipid metabolism. The expression levels of several key genes involved in salt tolerance, namely SeSOS1, SeNHX1, SeVHA-A, SeVP1, and SePSS, were found to be upregulated upon NaCl treatment. A total of 485 lipid compounds were identified, of which 27 changed in abundance under salt treatment, including the enrichment of phospholipids and sphingolipids. Moreover, the increase in the double-bond index (DBI) was mainly due to phospholipids and sphingolipids. Comparing the acyl chain length (ACL) showed that the ACL coefficient of S1P significantly decreased under 200mM NaCl. This study suggests that S. europaea adapt to saline environments through altering phospholipids and sphingolipids to improve salt tolerance. The salinity response of S. europaea can provide important insights into the action of lipids and their salt adaptation mechanisms.

Profiling of conserved orthologs and miRNAs for understanding their role in salt tolerance mechanism of Sesuvium portulacastrum L.

Sesuvium portulacastrum is a facultative halophyte capable of thriving in a saline environment. Despite molecular studies conducted to unravel its salt adaptation mechanism, there is a paucity of information on the role of salt-responsive orthologs and microRNAs (miRNAs) in this halophyte. Here, we searched the orthology to identify salt-responsive orthologs and miRNA targets of Sesuvium using the Arabidopsis genome. The relative fold change of orthologs, conserved miRNAs, and miRNA targets of Sesuvium was analyzed under 100mM (LS) and 250mM NaCl (HS) treatment at 24h using qRT-PCR. The comparison between the expression of Sesuvium orthologs and Arabidopsis orthologs (Arabidopsis eFP browser database) was used to identify differentially expressed genes. Upon salt treatment, we found that SpCIPK3 (1.95-fold in LS and 2.90-fold in HS) in Sesuvium roots, and SpNHX7 (1.61-fold in LS and 6.39-fold in HS) and, SpSTPK2 (2.54-fold in LS and 7.65-fold in HS) in Sesuvium leaves were upregulated in a salt concentration-specific manner. In Arabidopsis, these genes were either downregulated or did not show significant variation, implicating its significance in the halophytic nature of Sesuvium. Furthermore, miRNAs like miR394a, miR396a, and miR397a exhibited a negative correlation with their targets-Frigida interacting protein 1, Cysteine proteinases superfamily protein, and Putative laccase, respectively under different salt treatments. The study revealed that the high salt tolerance in Sesuvium is associated with distinct transcriptional reprogramming, hence, to gain holistic mechanistic insights, global-scale profiling is required.

Nitrogen removal from high-saline municipal wastewater via anammox-based process driven by both nitritation and denitratation

Nitrogen removal from saline municipal wastewater has recently attracted attention; thus, developing energy-efficient technology such as anaerobic ammonium oxidation (anammox) for advanced nitrogen removal of hypersaline wastewater is significant. In this study, the long-term salt adaptation and evolution mechanisms of an anammox-based process driven by both nitritation (NH4+→NO2—, PN) and denitratation (NO3—→NO2—, PD) were investigated under salinities ranging from 1.0% to 3.0% (10–30 g NaCl/L). At 1.0% salinity, PN evolved into the major nitrite production pathway with thorough suppression of nitrite oxidation. At 1.5% salinity, nitrite reduction was inhibited along with suspended sludge loss due to poor sludge settleability. Under 2.0% salinity with only-biofilm, the highest nitrogen removal efficiency (81.2%) was observed with influent and effluent total inorganic nitrogen concentrations of 44.5 and 8.2 mg N/L, respectively. Notably, results showed that anammox bacteria occupied up to 1.07% of the microbial community (qPCR: 1.14×1011 copies/(g dry sludge)) and has strong adaptability to salinity. With salinity increases, anammox contribution kept over 85% and Ca. Kuenenia (0.57%→0.22%) was more tolerant than Ca. Brocadia (0.46%→0.02%). Metagenomic sequencing revealed that the multiple nitrite substrates production by Nitrosomonas (amoA-enriched), Denitratisoma and Denitromonas (narG-enriched) guaranteed the high anammox contribution. This study provides a multifaceted understanding of the anammox-based process, which can enable improved application in real saline wastewater treatment.

Rationally tailoring the halophilicity of an amylolytic enzyme for application in dehydrating conditions

Rationally engineering mesophilic enzymes to function efficiently in dehydrating conditions is of great interest since saline and hypersaline environments are prevailing in many industrial processes. Here, targeted mutagenesis and structural comparison identified that the surface charge distribution is a structure feature in determining the halophilicity of α-amylase Ha-Amy, which enables to rationally tailor protein halophilicity by engineering local charge density on protein surface. Importantly, such modification can be applied to non-catalytic domains, which is highly appreciated in protein engineering in consideration of minimizing the adverse effects on catalytic efficiency. Our results not only provide more insights into the protein salt-adaptation mechanisms but allow to confer salt-tolerant property on mesophilic proteins for actual application in dehydrating conditions.

不同分布区胀果甘草原生境土壤微生物群落结构特征及其影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 不同分布区胀果甘草原生境土壤微生物群落结构特征及其影响因素 DOI: 10.5846/stxb202108022098 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31760046） Soil microbial community structure and its influencing factors in original habitat of Glycyrrhiza inflata in different distribution areas Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:胀果甘草（Glycyrrhiza inflata）主要分布于新疆、甘肃的荒漠区，是耐盐性最强的药用甘草，在改良盐碱地土壤中发挥着重要作用，其原生境土壤微生物群落结构特征是揭示种群分布影响因素及盐碱地修复机制的重要依据。从胀果甘草5个主产区采集原生境土壤，测定土壤理化指标，并采用高通量测序技术，结合Spearman、dbRDA等方法开展微生物群落组成及多样性特征研究，揭示不同分布区的优势微生物群落特征和影响因子。结果表明：真菌群落中曲霉属（Aspergillus）、地丝霉属（Geomyces）、镰刀菌属（Fusarium）和细菌群落中的寡养单胞菌属（Stenotrophomonas）、Marinimicrobium、Idiomarina是野生胀果甘草原生境土壤中的优势微生物类群。不同分布区的土壤真菌多样性和丰富度具有显著差异，但土壤细菌多样性和丰富度差异不显著；部分分布区土壤中的真菌和细菌种类差异较大。土壤理化因子中，土壤含水量和总含盐量对真菌和细菌的群落分布、丰富度有显著影响。原生境含水量与曲霉属（Aspergillus）、镰刀菌属（Fusarium）、链格孢属（Alternaria）、青霉属（Penicillium）真菌呈显著负相关；与Marinnimicrobium，Idiomarina、Aliifodinibius和需盐杆菌属（Salegentibacter）细菌呈显著正相关，与链霉菌属（Streptomyces）细菌呈显著负相关。原生境土壤总含盐量，与曲霉属（Aspergillus）、裸子囊菌属（Gymnoascus）、Aporospora真菌呈显著正相关，与镰刀菌属（Fusarium）、丝盖伞属（Inocybe）、硬皮马勃属（Scleroderma）真菌呈显著负相关；总盐含量与Marinimicrobium、Idiomarina、嗜盐单胞菌属（Halomonas）、Aliifodinibius、Salinimicrobium、需盐杆菌属（Salegentibacter）这6种细菌的丰富度存在显著正相关关系，与链霉菌属（Streptomyces）和鞘氨醇单胞菌属（Sphingomonas）细菌呈显著负相关。另外，土壤真菌和细菌的空间分布的异质性也与野生胀果甘草的生境类型和地理环境有关。原生境中丰富度高的嗜盐细菌可能与胀果甘草的盐适应和耐盐机制有密切关系。研究结果为野生胀果甘草的种群恢复、盐碱弃耕地的土壤功能修复研究提供理论依据。 Abstract:Glycyrrhiza inflata is mainly distributed in the desert areas of Xinjiang and Gansu. It is the most salt tolerant medicinal Glycyrrhiza, and plays an important role in improving saline alkali soil. The soil microbial community structure of original habitat is an important basis to reveal the influencing factors of population distribution and the restoration mechanism of saline alkali soil of Glycyrrhiza inflata. In this study, the original habitat soil was collected from five main production areas of Glycyrrhiza inflata, the soil physical and chemical indexes were measured, and the microbial community composition and diversity characteristics were studied by high-throughput sequencing technology combined with Spearman, dbRDA and other methods, so as to reveal the characteristics and influencing factors of dominant microbial communities in different distribution areas. The results showed that Aspergillus, Geomyces, Fusarium in the fungal community, and Stenotrophomonas, Marinimicrobium, and Idiomarina in the bacterial community were the dominant soil microbial groups of the wild Glycyrrhiza inflata habitat. There were significant differences in soil fungal diversity and richness in different distribution areas, but there was no significant difference in soil bacterial diversity and richness. The species of fungi and bacteria in some distribution areas were quite different. Among the soil physical and chemical factors, soil water content and total salinity had significant effects on the community distribution and richness of fungi and bacteria. In original habitat water content was significantly negatively correlated with Aspergillus, Fusarium, Alternaria, Penicillium; significantly positively correlated with Marinnimicrobium, Idiomarina, Aliifodinibius and Salegentibacter, and significantly negatively correlated with Streptomyces. In original habitat soil total salt content was significantly positively correlated with Aspergillus, Gymnoascus, Aporospora, and significantly negatively correlated with Fusarium, Inocybe, Scleroderma; total salt content was significantly correlated with six species of Marinimicrobium, Idiomarina, Halomonas, Aliifodinibius, Salinimicrobium, and Salegentibacter. There was a significant positive correlation between bacterial abundance and a significant negative correlation with Streptomyces and Sphingomonas. In addition, the heterogeneity of the spatial distribution of soil fungi and bacteria was also related to the habitat type and geographical environment of wild Glycyrrhiza inflata. Halomonas, Aliifodinibius and Salegentibacter in this study are all halophilic bacteria in the habitat of Glycyrrhiza inflata. The high abundance of halophilic bacteria in the original habitat may be closely related to the salt adaptation and salt tolerance mechanism of Glycyrrhiza inflata. The results provide a theoretical basis for the population restoration of wild Glycyrrhiza inflata and the soil function restoration of saline alkali abandoned farmland. 参考文献 相似文献 引证文献

Living with Salt

Living with Salt

Unveiling Purple Bacteria Salt Tolerance Mechanisms for Environmental Monitoring in Photo-Bioelectrochemical Systems

Photo-bioelectrochemical systems allow for the integration of photosynthetic bacteria at an electrode surface for the conversion of solar energy into electrical current.1 Among various applications, these systems open for the continuous monitoring of toxic compounds in the environment based on their cytotoxic effects on bacteria activity. However, a challenge for the on-field application is the exposure of bacterial cells to a diverse range of condition, requiring robust, versatile microorganisms capable of tolerating dynamic environments. Rhodobacter capsulatus (R. capsulatus) is a purple, photosynthetic bacterium with an outstanding versatile metabolism. Specifically, its versatility is thought to be due to a bacteria phage-like element, the R. capsulatus gene transfer agent (rcGTA), enabling horizontal gene transfer across microorganisms, which results in an expedited evolution to new environmental stresses. The rcGTA has been seen to facilitate resistance to antibiotics2 and provides a mechanism for adaptation to various environmental conditions. Integrating this bacterium with an electrode for photo-bioelectrochemical system development proves to be challenging due to the active redox center’s location inside of the thick cellular membrane. Previous work in our group has succeeded in mediating this redox active center employing monomeric quinones for mediating the extracellular electron transfer to the electrode.3 Current research is focused on engineering redox hydrogels to enhance the extracellular electron transfer in high saline, resulting in equal or higher currents compared to non-saline. To further improve photo-bioelectrocatalysis performance through adaptation of the cells to high saline conditions, we investigated the adaptation mechanism using techniques to study the rcGTA, and bioinformatics to evaluate differential expression of genes in both saline and non-saline conditions. Further research will be focused on harnessing these findings to decrease adaptation time to high salinities and evaluating the bioelectrochemical performance of these adapted strains through chronoamperometry and cyclic voltammetry experiments. The successful completion of this study will contribute towards the design of a photo-bioelectrochemical system for toxic compound detection in high saline conditions, and further increase our knowledge of salt adaptation mechanisms and the gene transfer agent of Rhodobacter capsulatus.

Transcriptome sequencing and functional analysis of Sedum lineare Thunb. upon salt stress

Soil salinization is one major constraint to plant geographical distribution, yield, and quality, and as an ideal plant for the "greening" of flat-roofed buildings, Sedum lineare Thunb. has strong tolerance against a variety of environmental adversities including salinity with the underlying mechanism still remaining unknown. In this study, we performed de novo transcriptome sequencing on leaf and root samples of NaCl-treated S. lineare Thunb. and identified 584 differentially expressed genes (DEGs), which were further annotated by gene function classification and pathway assignments using the public data repositories. In addition to the increased gene expression level verified by qRT-PCR, the elevated activities of the corresponding enzymes were also demonstrated for peroxidase (POD), glutathione peroxidases (GPX), and cysteine synthase (CSase) in the NaCl-treated roots. Furthermore, two highly inducible genes without known functions related to salt tolerance were selected to be overexpressed and tested for their effects on salt tolerance in the model plant, Arabidopsis thaliana. Upon 150mM NaCl treatment, 35S:SlCXE but not 35S:SlCYP72A transgenic Arabidopsis seedlings exhibited improved salt resistance as shown by the increased seed germination rates and longer primary roots of transgenic seedlings when compared to wild-type plants. Taken together, this work laid a foundation for a better understanding of the salt adaptation mechanism of S. lineare Thunb. and genes identified could serve as useful resources for the development of more salt-tolerant varieties of other species through genetic engineering.

Full-length transcriptome sequences of ephemeral plant Arabidopsis pumila provides insight into gene expression dynamics during continuous salt stress

BackgroundArabidopsis pumila is native to the desert region of northwest China and it is extraordinarily well adapted to the local semi-desert saline soil, thus providing a candidate plant system for environmental adaptation and salt-tolerance gene mining. However, understanding of the salt-adaptation mechanism of this species is limited because of genomic sequences scarcity. In the present study, the transcriptome profiles of A. pumila leaf tissues treated with 250 mM NaCl for 0, 0.5, 3, 6, 12, 24 and 48 h were analyzed using a combination of second-generation sequencing (SGS) and third-generation single-molecule real-time (SMRT) sequencing.ResultsCorrection of SMRT long reads by SGS short reads resulted in 59,328 transcripts. We found 8075 differentially expressed genes (DEGs) between salt-stressed tissues and controls, of which 483 were transcription factors and 1157 were transport proteins. Most DEGs were activated within 6 h of salt stress and their expression stabilized after 48 h; the number of DEGs was greatest within 12 h of salt stress. Gene annotation and functional analyses revealed that expression of genes associated with the osmotic and ionic phases rapidly and coordinately changed during the continuous salt stress in this species, and salt stress-related categories were highly enriched among these DEGs, including oxidation–reduction, transmembrane transport, transcription factor activity and ion channel activity. Orphan, MYB, HB, bHLH, C3H, PHD, bZIP, ARF and NAC TFs were most enriched in DEGs; ABCB1, CLC-A, CPK30, KEA2, KUP9, NHX1, SOS1, VHA-A and VP1 TPs were extensively up-regulated in salt-stressed samples, suggesting that they play important roles in slat tolerance. Importantly, further experimental studies identified a mitogen-activated protein kinase (MAPK) gene MAPKKK18 as continuously up-regulated throughout salt stress, suggesting its crucial role in salt tolerance. The expression patterns of the salt-responsive 24 genes resulted from quantitative real-time PCR were basically consistent with their transcript abundance changes identified by RNA-Seq.ConclusionThe full-length transcripts generated in this study provide a more accurate depiction of gene transcription of A. pumila. We identified potential genes involved in salt tolerance of A. pumila. These data present a genetic resource and facilitate better understanding of salt-adaptation mechanism for ephemeral plants.

Transcriptomic analysis reveals the molecular adaptation to NaCl stress in Zostera marina L.

The seagrass Zostera marina L. shows optimal growth in marine water and reduced growth under low salinity conditions. However, little is known about the molecular mechanisms underlying its adaptation to high salinity in Z. marina. In this study, transcriptomic analyses were performed using RNA-seq of the following two groups with different NaCl content: the CK group (seagrasses grown in the absence of NaCl) and the NaCl group (seagrasses grown in the presence of 400 mM NaCl for 6 h). Approximately 316 million high-quality reads were generated, and 87.9% of the data were mapped to the reference genome. Moreover, differentially expressed genes between the CK and NaCl groups were identified. According to a functional analysis, the up-regulated genes after the NaCl treatment were significantly enriched in nitrogen metabolism, calcium signalling and DNA replication while the down-regulated genes were significantly enriched in photosynthesis. A comparative transcriptomic analysis detected many differentially expressed genes and pathways required for adaptation to NaCl stress, providing a foundation for future studies investigating the molecular mechanisms of salt adaptation in Z. marina. We discuss how molecular changes in these processes may have contributed to the NaCl adaptation.

Key Metabolites and Mechanistic Changes for Salt Tolerance in an Experimentally Evolved Sulfate-Reducing Bacterium, Desulfovibrio vulgaris.

ABSTRACTRapid genetic and phenotypic adaptation of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough to salt stress was observed during experimental evolution. In order to identify key metabolites important for salt tolerance, a clone, ES10-5, which was isolated from population ES10 and allowed to experimentally evolve under salt stress for 5,000 generations, was analyzed and compared to clone ES9-11, which was isolated from population ES9 and had evolved under the same conditions for 1,200 generations. These two clones were chosen because they represented the best-adapted clones among six independently evolved populations. ES10-5 acquired new mutations in genes potentially involved in salt tolerance, in addition to the preexisting mutations and different mutations in the same genes as in ES9-11. Most basal abundance changes of metabolites and phospholipid fatty acids (PLFAs) were lower in ES10-5 than ES9-11, but an increase of glutamate and branched PLFA i17:1ω9c under high-salinity conditions was persistent. ES9-11 had decreased cell motility compared to the ancestor; in contrast, ES10-5 showed higher cell motility under both nonstress and high-salinity conditions. Both genotypes displayed better growth energy efficiencies than the ancestor under nonstress or high-salinity conditions. Consistently, ES10-5 did not display most of the basal transcriptional changes observed in ES9-11, but it showed increased expression of genes involved in glutamate biosynthesis, cation efflux, and energy metabolism under high salinity. These results demonstrated the role of glutamate as a key osmolyte and i17:1ω9c as the major PLFA for salt tolerance in D. vulgaris. The mechanistic changes in evolved genotypes suggested that growth energy efficiency might be a key factor for selection.

Identification and validation of reference genes for quantitative real-time PCR under salt stress in a halophyte, Sesuvium portulacastrum

Sesuvium portulacastrum L. is a facultative halophyte with potential applications in phytoremediation and phytodesalination and offers as a system to understand mechanisms of salt adaptation. However, studies on gene identification, characterization and transcriptomics of this halophyte are limited due the paucity of genome sequence information and validation of gene expression data through quantitative real time-PCR (qRT-PCR). qRT-PCR is a reliable method for exact quantification of gene expression, but is dependent upon the selection of suitable reference gene(s). In the present study, using Sesuvium RNA-Seq data, we identified ten reference genes such as elongation factor 1-α, ubiquitin-conjugating enzyme E2, TATA-box binding protein, DnaJ-like protein, β-tubulin, glyceraldehyde 3-phosphate dehydrogenase, eukaryotic initiation factor 4a, RNA-dependent RNA polymerase 1, α-tubulin and pentatricopeptide repeat and validated their stable expression in root and shoot tissues under 0, 100 and 250mM NaCl stress conditions. Five different statistical methods viz. Delta Ct, NormFinder, BestKeeper, geNorm and ReFinder were used to establish the most suitable reference genes for root (UCE 2, TBP, EF1-α) and shoot (α-TUB, EIF4a, EF1-α). Additionally, the expression of five salt responsive genes was calculated under salt stress using the best reference genes and compared with RNA-Seq data. The comparison between real time and RNA-Seq data showed a high correlation (r2=0.875), supporting the selection of the suitable reference genes. This study provides a good starting platform for successful gene quantification in S. portualcastrum.

Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity.

BackgroundSoil salinity affects growth and yield of crop plants. Plants respond to salinity by physiological and biochemical adjustments through a coordinated regulation and expression of a cascade of genes. Recently, halophytes have attracted attention of the biologists to understand their salt adaptation mechanisms. Spartina alterniflora (smooth cordgrass) is a Louisiana native monocot halophyte that can withstand salinity up to double the strength of sea water. To dissect the molecular mechanisms underlying its salinity adaptation, leaf and root transcriptome of S. alterniflora was sequenced using 454/GS-FLX.ResultsAltogether, 770,690 high quality reads with an average length 324-bp were assembled de novo into 73,131 contigs (average 577-bp long) with 5.9X sequence coverage. Most unigenes (95 %) annotated to proteins with known functions, and had more than 90 % similarity to rice genes. About 28 % unigenes were considered specific to S. alterniflora. Digital expression profiles revealed significant enrichment (P < 0.01) of transporters, vacuolar proton pump members and transcription factors under salt stress, which suggested the role of ion homeostasis and transcriptional regulation in the salinity adaptation of this grass. Also, 10,805 SSRs markers from 9457 unigenes were generated and validated through genetic diversity analysis among 13 accessions of S. alterniflora.ConclusionsThe present study explores the transcriptome of S. alterniflora to understand the gene regulation under salt stress in halophytes. The sequenced transcriptome (control and salt-regulated) of S. alterniflora provides a platform for further gene finding studies in grasses. This study and our previously published studies suggested that S. alterniflora is a rich reservoir of salt tolerance genes that can be used to develop salt tolerant cereal crops, especially rice, a major food crop of global importance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3017-3) contains supplementary material, which is available to authorized users.

Choline priming-induced plasma membrane lipid alterations contributed to improved wheat salt tolerance

Salt stress is a major environmental threat influencing crop growth and yield. The plasma membrane (PM) is believed to be one facet of the cellular mechanisms of salt adaptation. Choline priming has been reported to enhance salt tolerance of the sensitive wheat cultivar used in this work. The study was, therefore, undertaken to examine whether changes in the PM lipids will participate in choline-improved salt tolerance. The caryopses were primed in choline chloride (0, 5 and 10 mM) for 24 h. They were then germinated in sand for 10 days, watered with 1/4-strength modified Hoagland solution (MHS). The seedlings were grown in the sand, watered with MHS containing 150 mM NaCl for 3 weeks. Root PM was isolated by two-phase partitioning method and its lipid classes were determined. Choline maintained the PM total lipids, sterol and phospholipids, which were altered by NaCl. The PM sterols/phospholipids ratio was decreased by NaCl, whereas choline retained this ratio. Salt stress reduced the PM unsaturated fatty acids while increased its saturated fatty acids. Choline alleviated PM unsaturated/saturated ratio reduction. NaCl declined the PM phosphatidylcholine (PC), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) whereas increased phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE). Choline decreased PS and PE, while increased PC level. The PM cholesterol, campesterol and β-sitosterol were increased while stigmasterol was declined under NaCl. Choline increased stigmasterol whereas decreased cholesterol and campesterol. The alterations in the PM lipids were discussed in relation to choline-enhanced salt tolerance.

Salt tolerance research in date palm tree (Phoenix dactylifera L.), past, present, and future perspectives.

The date palm can adapt to extreme drought, to heat, and to relatively high levels of soil salinity. However, excessive amounts of salt due to irrigation with brackish water lead to a significant reduction in the productivity of the fruits as well as marked decrease in the viable numbers of the date palm trees. It is imperative that the nature of the existing salt-adaptation mechanism be understood in order to develop future date palm varieties that can tolerate excessive soil salinity. In this perspective article, several research strategies, obstacles, and precautions are discussed in light of recent advancements accomplished in this field and the properties of this species. In addition to a physiological characterization, we propose the use of a full range of OMICS technologies, coupled with reverse genetics approaches, aimed toward understanding the salt-adaption mechanism in the date palm. Information generated by these analyses should highlight transcriptional and posttranscriptional modifications controlling the salt-adaptation mechanisms. As an extremophile with a natural tolerance for a wide range of abiotic stresses, the date palm may represent a treasure trove of novel genetic resources for salinity tolerance.

High-throughput deep sequencing reveals that microRNAs play important roles in salt tolerance of euhalophyte Salicornia europaea

BackgroundmicroRNAs (miRNAs) are implicated in plant development processes and play pivotal roles in plant adaptation to environmental stresses. Salicornia europaea, a salt mash euhalophyte, is a suitable model plant to study salt adaptation mechanisms. S. europaea is also a vegetable, forage, and oilseed that can be used for saline land reclamation and biofuel precursor production on marginal lands. Despite its importance, no miRNA has been identified from S. europaea thus far.ResultsDeep sequencing was performed to investigate small RNA transcriptome of S. europaea. Two hundred and ten conserved miRNAs comprising 51 families and 31 novel miRNAs (including seven miRNA star sequences) belonging to 30 families were identified. About half (13 out of 31) of the novel miRNAs were only detected in salt-treated samples. The expression of 43 conserved and 13 novel miRNAs significantly changed in response to salinity. In addition, 53 conserved and 13 novel miRNAs were differentially expressed between the shoots and roots. Furthermore, 306 and 195 S. europaea unigenes were predicted to be targets of 41 conserved and 29 novel miRNA families, respectively. These targets encoded a wide range of proteins, and genes involved in transcription regulation constituted the largest category. Four of these genes encoding laccase, F-box family protein, SAC3/GANP family protein, and NADPH cytochrome P-450 reductase were validated using 5′-RACE.ConclusionsOur results indicate that specific miRNAs are tightly regulated by salinity in the shoots and/or roots of S. europaea, which may play important roles in salt tolerance of this euhalophyte. The S. europaea salt-responsive miRNAs and miRNAs that target transcription factors, nucleotide binding site-leucine-rich repeat proteins and enzymes involved in lignin biosynthesis as well as carbon and nitrogen metabolism may be applied in genetic engineering of crops with high stress tolerance, and genetic modification of biofuel crops with high biomass and regulatable lignin biosynthesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0451-3) contains supplementary material, which is available to authorized users.

NaCl胁迫下沙枣幼苗生长和阳离子吸收、运输与分配特性

PDF HTML阅读 XML下载 导出引用 引用提醒 NaCl胁迫下沙枣幼苗生长和阳离子吸收、运输与分配特性 DOI: 10.5846/stxb201303270530 作者: 作者单位: 林木遗传育种国家重点实验室，国家林业局盐碱地研究中心,林木遗传育种国家重点实验室，国家林业局盐碱地研究中心,林木遗传育种国家重点实验室;国家林业局盐碱地研究中心,林木遗传育种国家重点实验室;国家林业局盐碱地研究中心,北京市林业勘察设计院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家“十二五”科技支撑计划资助项目（2011BAD38B0102）；中央级公益性科研院所基本科研业务费专项资金资助项目（CAFYBB2011005-5） Growth, and cationic absorption, transportation and allocation of Elaeagnus angustifolia seedlings under NaCl stress Author: Affiliation: State Key Laboratory of Tree Genetics and Breeding;Research Center for Saline-alkali Land, State Forestry Administration,State Key Laboratory of Tree Genetics and Breeding;Research Center for Saline-alkali Land, State Forestry Administration,State Key Laboratory of Tree Genetics and Breeding;Research Center for Saline-alkali Land, State Forestry Administration,State Key Laboratory of Tree Genetics and Breeding;Research Center for Saline-alkali Land, State Forestry Administration,Beijing Forestry Survey and Design Institute Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:沙枣（Elaeagnus angustifolia L.）耐盐性强，是我国北方生态脆弱地区造林绿化的一个先锋树种。为探讨沙枣的盐适应机制，研究了不同浓度NaCl（0、100和200 mmol/L）胁迫30d对其水培幼苗生物量累积以及不同组织（根、茎、叶）K+、Na+、Ca2+和Mg2+吸收、运输与分配的影响。结果表明：盐胁迫不同程度地促进了沙枣苗根系生长；100 mmol/L NaCl胁迫对幼苗生物量累积无明显影响，而200 mmol/L则显著抑制了生物量累积；盐胁迫幼苗根、茎、叶中Na+含量以及K+-Na+选择性运输系数（SK，Na）和Ca2+-Na+选择性运输系数（SCa，Na）显著或大幅度增加，而K+、Ca2+、Mg2+含量以及K+/Na+、Ca2+/Na+和Mg2+/Na+比值则显著或大幅度下降；200 mmol/L NaCl胁迫沙枣根Na+含量和根Na+净累积量分别为22.15 mg/g干重和1.87 mg/株（是对照的16.20倍和20.06倍），根成为Na+净累积量增加幅度最大的组织和Na+含量最高的组织；200 mmol/L NaCl胁迫沙枣茎、叶中的Na+含量以及冠组织Na+净累积量分别高达5.15、7.71 mg/g干重和3.29 mg/株（是对照的7.22倍、9.58倍和5.45倍），但幼苗仍能正常生长。综合分析认为，沙枣的盐适应机制是根系拒盐和冠组织耐盐，主要通过根系的补偿生长效应、根系对Na+的聚积与限制作用以及冠组织对Na+的忍耐来实现的，同时也与根、茎和叶对K+、Ca2+选择性运输能力显著增强有关。 Abstract:As a salt-tolerant shrub/tree species, Elaeagnus angustifolia L. is widely planted for afforestation in many marginal lands or environmentally harsh conditions in northern China. Although E. angustifolia is well known for its strong adaptation to harsh conditions, the underpinning physiological mechanisms associated with ion transport and homeostasis under high-salt conditions have not been revealed. Has it developed some physiological mechanisms to avoid the high Na+ in soil or sequester the Na+ in some specific tissues or organs? The use of E. angustifolia to answer these questions can greatly enhance our understanding of the general physiological mechanisms that plants deploy to combat the environmental challenges.To unravel the underlying physiological mechanisms responsible for the extra-ordinary adaptation to high salt in E. angustifolia, we used the well-controlled water culture experiment in greenhouse to investigate the biomass accumulation, and the absorption, transportation and allocation of multiple ions including K+, Na+, Ca2+ and Mg2+ in different plant tissues (roots, stems and leaves) of E. angustifolia seedlings upon being challenged by different NaCl concentrations (0, 100 and 200 mmol/L) for 30 days. Interestingly, the root growth was stimulated to a different extent by salt stress. The biomass accumulation of E. angustifolia seedlings was not obviously affected by 100 mmol/L NaCl stress, whereas it was significantly inhibited by 200 mmol/L NaCl stress. Compared with non-salt control, the K+-Na+ selective transportation coefficients (SK, Na) and Ca2+-Na+ selective transportation coefficients (SCa, Na) of different plant tissues (roots, stems and leaves) under two salt concentrations were all significantly elevated, while the contents of K+, Ca2+ and Mg2+, and the ratios of K+/Na+, Ca2+/Na+ and Mg2+/Na+ in the three plant tissues were all significantly decreased. The Na+ concentration and net Na+ accumulation in 200 mmol/L NaCl-stressed seedlings' roots were 22.15 mg/g DW and 1.87 mg/plant, respectively, which were 16.20 and 20.06 times higher than that in the control roots, respectively. The concentration and the accumulating amplitude of Na+ in roots were more conspicuous than any of other two tissues, implicating that roots may contribute vitally to the observed salt-tolerance of E. angustifolia. The Na+ concentration in stems and leaves of 200 mmol/L NaCl-stressed seedlings increased to 5.15 and 7.71 mg/g DW, which were 7.22 and 9.58 times the content in corresponding control, respectively, and net Na+ accumulation in 200 mmol/L NaCl-stressed seedlings' shoots was 3.29 mg/plant (5.45 times as much as in control shoot). However, all seedlings stressed by two salt concentrations exhibited a normal growth, no typical salt-damaged symptoms like succulent shoot and abscised leaves in treated seedlings were observed, indicating that shoots (including stems and leaves) can tolerate high concentration's Na+ stress. In conclusion, our findings suggested that the salt-adaptation mechanisms of E. angustifolia are root salt-rejection and shoot salt-tolerance, which are primarily implemented by root growth stimulation, root Na+ accumulation and restriction, and shoot Na+ endurance, and are also correlated with a remarkably increased ability of K+ and Ca2+ selective transportation in roots, stems and leaves. 参考文献 相似文献 引证文献

Osmoadaptive Strategies of the ArchaeonHalococcus hamelinensisIsolated from a Hypersaline Stromatolite Environment

Biogenic stromatolites are sources of significant information on the evolution of microbial life. Despite their evolutionary significance, little is known about the mechanisms of osmoadaptation by microorganisms that comprise living stromatolites thriving in hypersaline environments. Osmoadaptive strategies for Halococcus hamelinensis, a novel halophilic archaeon recently isolated from living stromatolites in the hypersaline reaches of Shark Bay, were thus a particular interest in this study. To investigate the possibility of "salt-in-cytoplasm"-associated osmoadaptation for this archaeon, flame photometry studies were performed. From the results, it was evident that this halophilic archaeon did not accumulate intracellular K(+) ions when cells were exposed to either osmotic shock or conditions with gradual increments in salinity. These results were further supported by polymerase chain reaction (PCR) analyses where there was no evidence for the existence of homologous genes to an ATP-driven, high-affinity potassium uptake system in Halococcus hamelinensis. To identify an alternative salt adaptation mechanism associated with accumulation of compatible solutes for this archaeon, (1)H nuclear magnetic resonance (NMR) spectroscopy experiments were carried out. Results indicate that glycine betaine, trehalose, and glutamate are solutes likely to be involved in osmoregulation in this archeaon. Subsequent (1)H NMR analysis of cell extracts from this microorganism grown under various NaCl concentrations revealed that intracellular levels of glycine betaine increased with increasing concentrations of NaCl. This behavior of increasing glycine betaine concentration with increasing external NaCl is consistent with its identity as an osmolyte. In contrast, intracellular levels of trehalose were decreased in high concentrations of NaCl. This provides evidence that compatible solute accumulation appears to be the preferential salt regulation mechanism for this haloarchaeon, in contrast to the salt-in-cytoplasm strategy employed by many other halophilic archaea.

In the halotolerant Lobularia maritima (Brassicaceae) salt adaptation correlates with activation of the vacuolar H +-ATPase and the vacuolar Na +/H + antiporter

Lobularia maritima (Brassicaceae) is a facultative halophyte related to Arabidopsis thaliana and may be a suitable model to identify molecular mechanisms that regulate tolerance to salt stress in plants. Under the same salt stress conditions, the accumulation of sodium was similar in shoots and roots of Lobularia maritima and Arabidopsis thaliana, whereas the sodium to potassium ratio was less in Lobularia maritima. Aquaporins, the NHX-type Na(+)/H(+) antiporter, and the vacuolar ATPase are well established targets of regulation under salt stress that have a central role in the control of water status and cytoplasmic sodium homeostasis. Therefore, salt-dependent expression of transcripts encoding a PIP2;1 aquaporin, the Na(+)/H(+) antiporter NHX, and V-ATPase subunit E (VHA-E) was characterized in Lobularia maritima. Transcription of LmPIP2;1 was repressed in leaves and roots by treatment with 500mM NaCl. In contrast, salt stress stimulated the expression of LmNHX1 and LmVHA-E. Cell-specificity of the transcription of LmNHX1 was analyzed by fluorescence in situ PCR in leaf cross sections of Lobularia maritima. Expression of the gene was localized to the phloem and to mesophyll cells. In plants treated with 500 mM NaCl, transcription of LmNHX1 was stimulated in the mesophyll. The findings indicate divergent transcriptional responses of key mechanisms of salt adaptation in Lobularia maritima and suggest distinct regulation of sodium homeostasis and water flux under salt stress.

식물의 고염 스트레스에 대한 반응 및 적응기작

Plant responses to salinity stress is critical in determining the growth and development. Therefore, adaptability of plant to salinity stress is directly related with agriculture productivity. Salt adaptation is a result of the integrated functioning of numerous determinants that are regulated coordinately through an appropriate responsive signal transduction cascade. The cascade perceives the saline environment and exerts control over the essential mechanisms that are responsible for ion homeostasis and osmotic adjustment. Although little is known about the component elements of salt stress perception and the signaling cascade(s) in plant, the use of Arabidopsis plant as a molecular genetic tool has been provided important molecular nature of salt tolerance effectors and regulatory pathways. In this review, I summarize recent advances in understanding the molecular mechanisms of salt adaptation.