Halogeton Research Articles

Planting halophytes increases the rhizosphere ecosystem multifunctionality via reducing soil salinity

Soil salinization poses a significant global challenge, exerting adverse effects on both agriculture and ecosystems. Planting halophytes has the potential ability to improve saline-alkali land and enhance ecosystem multifunctionality (EMF). However, it remains unclear which halophytes are effective in improving saline-alkali land and what impact they have on the rhizosphere microbial communities and EMF. In this study, we evaluated the Na+ absorption capability of five halophytes (Grubovia dasyphylla, Halogeton glomeratus, Suaeda salsa, Bassia scoparia, and Reaumuria songarica) and assessed their rhizosphere microbial communities and EMF. The results showed that S. salsa possessed the highest shoot (3.13 mmol g−1) and root (0.92 mmol g−1) Na+ content, and its soil Na+ absorption, along with B. scoparia, was significantly higher than that of other plants. The soil pH, salinity, and Na+ content of the halophyte rhizospheres decreased by 6.21%, 23.49%, and 64.29%, respectively, when compared to the bulk soil. Extracellular enzymes in the halophyte rhizosphere soil, including α-glucosidase, β-glucosidase, β-1,4-N-acetyl-glucosaminidase, neutral phosphatase, and alkaline phosphatase, increased by 70.1%, 78.4%, 38.5%, 79.1%, and 64.9%, respectively. Furthermore, the halophyte rhizosphere exhibited higher network complexity of bacteria and fungi and EMF than bulk soil. The relative abundance of the dominant phyla Proteobacteria, Firmicutes, and Ascomycota in the halophyte rhizosphere soil increased by 9.4%, 8.3%, and 22.25%, respectively, and showed higher microbial network complexity compared to the bulk soil. Additionally, keystone taxa, including Muricauda, Nocardioides, and Pontibacter, were identified with notable effects on EMF. This study confirmed that euhalophytes are the best choice for saline-alkali land restoration. These findings provided a theoretical basis for the sustainable use of saline-alkali cultivated land.

HgS2, a novel salt-responsive gene from the Halophyte Halogeton glomeratus, confers salt tolerance in transgenic Arabidopsis.

Halophyte Halogeton glomeratus mostly grows in saline desert areas in arid and semi-arid regions and is able to adapt to adverse conditions such as salinity and drought. Earlier transcriptomic studies revealed activation of the HgS2 gene in the leaf of H. glomeratus seedlings when exposed to saline conditions. To identify the properties of HgS2 in H. glomeratus, we used yeast transformation and overexpression in Arabidopsis. Yeast cells genetically transformed with HgS2 exhibited K+ uptake and Na+ efflux compared with control (empty vector). Stable overexpression of HgS2 in Arabidopsis improved its resistance to salt stress and led to a notable rise in seed germination in salinity conditions compared to the wild type (WT). Transgenic Arabidopsis regulated ion homeostasis in plant cells by increasing Na+ absorption and decreasing K+ efflux in leaves, while reducing Na+ absorption and K+ efflux in roots. In addition, overexpression of HgS2 altered transcription levels of stress response genes and regulated different metabolic pathways in roots and leaves of Arabidopsis. These results offer new insights into the role of HgS2 in plants' salt tolerance.

Enhanced methane production by using phytoremediated Halogeton glomeratus as substrate via anaerobic digestion

The phytoremediated plant contains rich carbon resources, but the anaerobic digestion (AD) process can be inhibited due to high Heavy metals (HMs). In this study, the phytoremediated Halogeton glomeratus (H. glomeratus) was utilized in AD. Results showed that suitable HMs improved the AD efficiency, and the HMs were positively correlated to methane production and microbiota. Compared to CK (without HMs contaminated), H. glomeratus containing HMs (TG) enhanced methane production (increased 85.5%). Also, the highest VS removal rate of 66.5% were achieved. Furthermore, the increased of hydrolytic and acidogenic Acinetbacter and Hydrogenophaga improved substrates degradation. Besides, the methanogenic Methanosarcina increased from 6.5 to 89.5%, and the methanogenic pathway shifted from hydrogenotrophic methanogenesis to aceticlastic methanogenesis. Thus, substrates conversion to methane was improved. Finally, the HMs in digestion slurry were successfully removed and decreased its secondary pollution. This study provided a potential for the resourceful utilization of the phytoremediated plants with suitable HMs concentration.

Negative effects of long-term exposure to salinity, drought, and combined stresses on halophyte Halogeton glomeratus.

Plants are subjected to salt and drought stresses concurrently but our knowledge about the effects of combined stress on plants is limited, especially on halophytes. We aim to study if some diverse drought and salt tolerance traits in halophyte may explain their tolerance to salinity and drought stresses, individual and in combination, and identify key traits that influence growth under such stress conditions. Here, the halophyte Halogeton glomeratus was grown under control, single or combinations of 60 days drought and salt treatments, and morphophysiological responses were tested. Our results showed that drought, salinity, and combination of these two stressors decreased plant growth (shoot height, root length, and biomass), leaf photosynthetic pigments content (chlorophyll a, b, a + b and carotenoids), gas exchange parameters (Net photosynthesis rate [PN ], transpiration rate [E], stomatal conductance [gs ]), and water potential (ψw ), and the decreases were more prominent under combined drought and salinity treatment compared with these two stressors individually performed. Similarly, combined drought and salinity treatment induced more severe oxidative stress as indicated by more hydrogen peroxide (H2 O2 ) and malondialdehyde (MDA) accumulated. Nevertheless, H. glomeratus is equipped with specific mechanisms to protect itself against drought and salt stresses, including upregulation of superoxide dismutases (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6) activities and accumulation of osmoprotectants (Na+ , Cl- , and soluble sugar). Our results indicated that photosynthetic pigments content, gas exchange parameters, water potential, APX activity, CAT activity, soluble sugar, H2 O2 , and MDA are valuable screening criteria for drought and salt, alone or combined, and provide the tolerant assessment of H. glomeratus.

Metabolomics Analyses Provide Insights Into Nutritional Value and Abiotic Stress Tolerance in Halophyte Halogeton glomeratus.

Halogeton glomeratus is a succulent annual herbaceous halophyte belonging to the Chenopodiaceae family, has attracted wide attention as a promising candidate for phytoremediation and as an oilseed crop and noodle-improver. More importantly, H. glomeratus has important medicinal value in traditional Chinese medicine. However, there are few comprehensive studies on the nutrients, particularly secondary metabolites. Here, we adopted untargeted metabolomics to compare the differences in metabolites of different tissues (root, stem, leaf, and seed) and identify the compounds related to pharmacological effects and response to abiotic stress in H. glomeratus. A total of 2,152 metabolites were identified, and the metabolic profiles of root, stem, leaf, and seed samples were clearly separated. More than 50% of the metabolites showed significant differences among root, stem, leaf, and seed. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of differential metabolites suggested an extensive alteration in the metabolome among the different organs. Furthermore, the identified metabolites related to pharmacological effects and response to abiotic stress included flavones, flavonols, flavandiols, glucosinolates, isoquinolines, pyridines, indoles, amino acids, lipids, carbohydrates, and ATP-binding cassette transporters. These metabolites have application in treating human cardiovascular diseases, cancers, diabetes, and heart disease, induce sleeping and have nutritive value. In plants, they are related to osmotic adjustment, alleviating cell damage, adjusting membrane lipid action and avoiding toxins. To the best of our knowledge, this is the first metabolomics-based report to overview the metabolite compounds in H. glomeratus and provide a reference for future development and utilization of H. glomeratus.

In vitro regeneration system of Halogeton glomeratus: an important halophyte

Halogeton glomeratus (H. glomeratus) is one of the most important halophytes in Asia, and the research on the genes and salt-tolerant mechanisms of this species is limited because of the lack of an optimal and efficient in vitro regeneration system. Here, we developed an efficient plant regeneration protocol using H. glomeratus leaves as explants, which has not been previously reported. High-quality calli were successfully obtained from the H. glomeratus leaves at a frequency of 100% supplemented with 2.00 mg/L 2,4-dichlorophenoxyacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose; the optimum callus subculture medium is 1.00 mg/L 2,4-dichlorophenoxyacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose. Shoots were regenerated on shoot induction medium at a frequency of 100% added with 0.50 mg/L 6-benzylaminopurine, 2.00 mg/L kinetin, 0.20 mg/L naphthaleneacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose; then, shoots grew up on shoot regeneration medium. Finally, roots were regenerated from the shoots on Murashige and Skoog medium with high efficiency. This study firstly offers a rapid and efficient system for plantlet regeneration from leaves of H. glomeratus. Whether our protocol applies well to other tissue regeneration of H. glomeratus needs further confirmation. This work will facilitate basic research and salt-tolerant mechanisms of this important halophyte species.

Influences of Heavy Metals and Salt on Seed Germination and Seedling Characteristics of Halophyte Halogeton glomeratus.

Heavy metals pollution and salinization of soils are widely distributed in agricultural soils. This study investigated the effects of five heavy metals and five heavy metals-contaminated salt on seed germination and seedling growth of halophyte Halogeton glomeratus (H. glomeratus). The results showed that seed germination, fresh weight (FW), dry weight (DW), radicles relative viability and ion contents (Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+) of H. glomeratus were affected by different heavy metals and heavy metal-polluted 100mM NaCl treatments. Ion contents in plumules increased with the increase of heavy metal concentrations with or without NaCl addition. Moreover, the accumulation levels of metals in the concentrations of Cu2+, Zn2+ and Pb2+ supplying 100mM NaCl were higher than that without NaCl treatment. This can provide new insights into the value of H. glomeratus for phytoremediation of soil affected by heavy metals and also in combination with salinity.

Effects of chloride and sulfate salts on seed germination of halophytes from dry alpine climate

A soil’s ionic profile along with other climatic factors influences seed germination in natural habitats. This study evaluates the role of different chloride and sulfate salts during germination of three halophytes (Halogeton glomeratus, Lepidium latifolium, and Peganum harmala) distributed in temperate salt playa habitats of Pakistan. Seeds were germinated in six salts concentrations (0 to 500 mM) under five temperature regimes (5/15 to 25/35 °C) and two photoperiods (12 h photoperiod and 24 h-dark). Germination percentage and germination velocity decreased with an increase in salt concentration and corresponding osmotic potentials. Germination of H. glomeratus and L. latifolium in iso-osmotic solutions of various salts was faster in K+ salts compared to Na+ and Mg2+ while in P. harmala germination was higher in Mg2+ and Na+ salts. H. glomeratus and L. latifolium were more tolerant to SO42− than Cl− salts, however, P. harmala was unaffected by anion. Optimal temperature was 20/30 °C for germination of all species irrespective of salt type. Sulfate seems to be less inhibitory only during germination of H. glomeratus in complete dark. The climatic condition of dry alpine habitat allows selected species to germinate at moderate temperature regimes (April–May) in the presence of light. High ionic concentration in soil may inhibit germination of all species but P. harmala appears to be more adapted in comparison to others. High sulfate soil content may favor seedling recruitment of H. glomeratus (annual plant) under mountain cracks.

Analysis and evaluation on seed nutrition of halophyte Halogeton glomeratus in arid region of northwest China

Analysis and evaluation on seed nutrition of halophyte Halogeton glomeratus in arid region of northwest China

Comparative transcriptome analysis of genes involved in Na+ transport in the leaves of halophyte Halogeton glomeratus

Compartmentalization of Na+ into vacuoles is considered to be the most critical aspect of salt tolerance in H. glomeratus, an annual, succulent halophyte. Previous analysis of transcriptome involved in the H. glomeratus salt stress response relied on next-generation sequencing technologies that limit the capture of accurately spliced, full-length isoforms. To gain deeper insights into its salt stress response, we used the H. glomeratus Iso-Seq transcriptome database as a reference, and subsequent next-generation sequencing was subjected to various NaCl concentrations of leaves from plants revealed 115 upregulated and 87 downregulated differentially expressed isoforms (core DEIs). The majority of the core DEIs were involved in carbohydrate metabolism and energy production and conversion. In contrast, levels of known isoforms encoding Na+ transporters did not change significantly under salt stress. However, 16 core DEIs of unknown function were predicted to possess transmembrane domains, suggesting that these candidate isoforms could be involved in Na+ transport in H. glomeratus. These results suggest a potential means for identification of novel Na+ transporters, in addition to providing a foundation for further investigation of Na+ transport networks in halophytes.

Niche opportunities for invasive annual plants in dryland ecosystems are controlled by disturbance, trophic interactions, and rainfall.

Resource availability and biotic interactions control opportunities for the establishment and expansion of invasive species. Studies on biotic resistance to plant invasions have typically focused on competition and occasionally on herbivory, while resource-oriented studies have focused on water or nutrient pulses. Through synthesizing these approaches, we identify conditions that create invasion opportunities. In a nested fully factorial experiment, we examined how chronic alterations in water availability and rodent density influenced the density of invasive species in both the Mojave Desert and the Great Basin Desert after fire. We used structural equation modeling to examine the direct and mediated effects controlling the density of invasives in both deserts. In the first 2 years after our controlled burn in the Great Basin, we observed that fire had a direct effect on increasing the invasive forb Halogeton glomeratus as well as a mediated effect through reducing rodent densities and herbivory. 4 years after the burn, the invasive annual grass Bromus tectorum was suppressing Halogeton glomeratus in mammal exclusion plots. There was a clear transition from years where invasives were controlled by disturbance and trophic interactions to years were resource availability and competition controlled invasive density. Similarly, in the Mojave Desert we observed a strong early influence of trophic processes on invasives, with Schismus arabicus benefitted by rodents and Bromus rubens negatively influenced by rodents. In the Mojave Desert, post-fire conditions became less important in controlling the abundance of invasives over time, while Bromus rubens was consistently benefitted by increases in fall rainfall.

Transcriptome sequencing and comparative analysis of differentially-expressed isoforms in the roots of Halogeton glomeratus under salt stress

Although Halogeton glomeratus (H. glomeratus) has been confirmed to have a unique mechanism to regulate Na+ efflux from the cytoplasm and compartmentalize Na+ into leaf vacuoles, little is known about the salt tolerance mechanisms of roots under salinity stress. In the present study, transcripts were sequenced using the BGISEQ-500 sequencing platform (BGI, Wuhan, China). After quality control, approximately 24.08 million clean reads were obtained and the average mapping ratio to the reference gene was 70.00%. When comparing salt-treated samples with the control, a total of 550, 590, 1411 and 2063 DEIs were identified at 2, 6, 24 and 72h, respectively. Numerous differentially-expressed isoforms that play important roles in response and adaptation to salt condition are related to metabolic processes, cellular processes, single-organism processes, localization, biological regulation, responses to stimulus, binding, catalytic activity and transporter activity. Fifty-eight salt-induced isoforms were common to different stages of salt stress; most of these DEIs were related to signal transduction and transporters, which maybe the core isoforms regulating Na+ uptake and transport in the roots of H. glomeratus. The expression patterns of 18 DEIs that were detected by quantitative real-time polymerase chain reaction were consistent with their respective changes in transcript abundance as identified by RNA-Seq technology. The present study thoroughly explored potential isoforms involved in salt tolerance on H. glomeratus roots at five time points. Our results may serve as an important resource for the H. glomeratus research community, improving our understanding of salt tolerance in halophyte survival under high salinity stress.

Salinity tolerance of three competing rangeland plant species: Studies in hydroponic culture.

Halogeton (Halogeton glomeratus) is an invasive species that displaces Gardner's saltbush (Atriplex gardneri) on saline rangelands, whereas, forage kochia (Bassia prostrata) potentially can rehabilitate these ecosystems. Salinity tolerance has been hypothesized as the predominant factor affecting frequency of these species. This study compared relative salinity tolerance of these species, and tall wheatgrass (Thinopyrum ponticum) and alfalfa (Medicago sativa). Plants were evaluated in hydroponics, eliminating the confounding effects of drought, for 28 days at 0, 150, 200, 300, 400, 600, and 800 mmol/L NaCl. Survival, growth, and ion accumulation were determined. Alfalfa and tall wheatgrass shoot mass were reduced to 32% of the control at 150 mmol/L. Forage kochia survived to 600 mmol/L, but mass was reduced at all salinity levels. Halogeton and Gardner's saltbush increased or maintained shoot mass up to 400 mmol/L. Furthermore, both actively accumulated sodium in shoots, indicating that Na+ was the principle ion in osmotic adjustment, whereas, forage kochia exhibited passive (linear) Na+ accumulation as salinity increased. This study confirmed the halophytic nature of these three species, but, moreover, discovered that Gardner's saltbush was as saline tolerant as halogeton, whereas, forage kochia was less tolerant. Therefore, factors other than salinity tolerance drive these species’ differential persistence in saline‐desert ecosystems.

Biologically Active Compounds from Halogeton glomeratus

Biologically Active Compounds from Halogeton glomeratus

Accumulation of heavy metals in native plants growing on mining-influenced sites in Jinchang: a typical industrial city (China)

Such activities as mining, metal ore smelting and the discharging of mining wastes lead to heavy metal contamination. Phytoremediation, including phytoextraction and phytostabilization, has been considered for a long time to be effective in remediating metal-polluted soils. This research assessed the chance of 40 plants (35 species) distributing on mining-influenced sites for phytoremediation purposes. The results showed that total soil Ni, Cu, Cd, Cr and Co concentrations were in the ranges of 107–3045, 116–2580, 7.1–22.7, 115–897 and 23.2–144.3 mg kg−1, respectively, whereas heavy metal contents in plants were in the ranges of 0.60–435.61, 2.41–298.31, 0.03–32.10, 0.08–88.20 and 0.11–28.52 mg kg−1, respectively. Therefore, no species can be used for phytoextraction purposes because no hyperaccumulator was identified. Salsola passerine, Stipa capillata, Cynanchum Chinense and Halogeton glomeratus with translocation factor (TF) > 1 for all five metals were considered to be accumulators. All plants were observed to hold a bioconcentration factor (BCF) 1, reflecting its low metal accumulation potential. Among the species studied, Oxytropis aciphylla, Salix matsudana, Tamarix hispida, Robinia pseudoacacia, Picea crassifolia, Lycium barbarum and Phragmites communis had both a BCF and TF < 1 for all five metals and were considered the most suitable for the phytostabilization of metal-polluted sites.

Competitive interactions between an exotic annual, Halogeton glomeratus, and 10 North American native species

Invasive plant species diminish ecosystem integrity and limit restoration success when they compete with reintroduced native species. The invasive annual forb halogeton ( Halogeton glomeratus (M. Bieb.) C.A. Mey. [Chenopodiaceae]) is increasing in abundance on disturbed lands and energy extraction sites in the Intermountain West. Successful seedings in the presence of halogeton in the past relied on competitive nonnative forage species. Because disturbance increases nutrient availability in otherwise stressful environments, we hypothesized that annual native species may be more competitive at the seedling stage than are perennial natives. We hypothesized that annuals would increase aboveground growth in the presence of the exotic while perennials would increase allocation to root growth. We documented growth and survival of halogeton in the presence of 10 species native to the western North American basin shrublands and in monocultures. Sporobolus cryptandrus (Torr.) A. Gray (Poaceae), Gaillardia aristata Pursh (Asteraceae), and Helianthus annuus L. (Asteraceae) reduced survival of halogeton ( Sporobolus and Gaillardia had greater biomass while Helianthus grew taller in the presence of halogeton than when grown with conspecifics. Halogeton aboveground growth was less when grown with H. annuus and Cleome serrulata Pursh (Capparaceae) (2 annual forbs). Annuals that demonstrated rapid biomass production also limited survival of halogeton. In general, perennials did not differ in aboveground tissue allocation in competition with halogeton. We suggest reclamation seedling establishment may be improved by including native annuals with the potential for rapid aboveground growth on arid land restoration sites where halogeton seedbanks persist.

Forage Kochia and Russian Wildrye Potential for Rehabilitating Gardner’s Saltbush Ecosystems Degraded by Halogeton

Gardner’s saltbush ecosystems are increasingly being invaded by halogeton (Halogeton glomeratus [M. Bieb.] C.A. Mey.), an annual halophyte that increases soil surface salinity and reduces plant biodiversity. Thus, a study was established in the Flaming Gorge National Recreation Area within the lower Green River Basin of Wyoming to evaluate the potential for rehabilitating halogeton-dominated Gardner’s saltbush ecosystems with forage kochia (Bassia prostrata [L.] A.J. Scott), Russian wildrye (Psathyrostachys juncea [Fisch.] Nevski), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth), and Gardner’s saltbush (Atriplex garneri [Moq.] D. Dietr.). A seeding evaluation, with and without prior disking, was conducted to determine ability of these species to establish. A transplant evaluation determined the effect of established plants on halogeton frequency at four 10-cm intervals (10–20, 20–30, 30–40, and 40–50 cm) distal from transplants. Gardner’s saltbush, tall wheatgrass, and Indian ricegrass did not establish in the seeded study or persist beyond the first year in transplant study. In contrast, Russian wildrye and forage kochia established and persisted, with Russian wildrye establishment higher (P = 0.05) in the disked treatment compared with no-till (4.5 and 1.7 plants m−2, respectively) and no-till favoring (P = 0.05) forage kochia establishment (2.3 and 0.8 plants m−2, respectively). Transplants of these two species reduced halogeton frequency by 52% relative to the control. Moreover, this interference of halogeton establishment by Russian wildrye and forage kochia had extended to 50 cm distal from transplant by the second year of the study. By the third year (2014), transplant survival and halogeton frequency were highly correlated (r = −0.61, P = 0.0001), indicating the importance of plant persistence. Results indicate that Russian wildrye and forage kochia can establish and reduce halogeton frequency, thereby providing an opportunity for rehabilitation of halogeton-invaded areas.

Comparative Proteomic Analysis of Cultured Suspension Cells of the Halophyte Halogeton glomeratus by iTRAQ Provides Insights into Response Mechanisms to Salt Stress.

Soil salinity severely threatens land use capability and crop yields worldwide. An analysis of the molecular mechanisms of salt tolerance in halophytes will contribute to the development of salt-tolerant crops. In this study, a combination of physiological characteristics and iTRAQ-based proteomic approaches was conducted to investigate the molecular mechanisms underlying the salt response of suspension cell cultures of halophytic Halogeton glomeratus. These cells showed halophytic growth responses comparable to those of the whole plant. In total, 97 up-regulated proteins and 192 down-regulated proteins were identified as common to both 200 and 400 mM NaCl concentration treatments. Such salinity responsive proteins were mainly involved in energy, carbohydrate metabolism, stress defense, protein metabolism, signal transduction, cell growth, and cytoskeleton metabolism. Effective regulatory protein expression related to energy, stress defense, and carbohydrate metabolism play important roles in the salt-tolerance of H. glomeratus suspension cell cultures. However, known proteins regulating Na+ efflux from the cytoplasm and its compartmentalization into the vacuole did not change significantly under salinity stress suggesting our existing knowledge concerning Na+ extrusion and compartmentalization in halophytes needs to be evaluated further. Such data are discussed in the context of our current understandings of the mechanisms involved in the salinity response of the halophyte, H. glomeratus.

Oilseed halophytes: a potential source of biodiesel using saline degraded lands

The financial and technical aspects of using edible plants as a biodiesel source have been studied extensively, but research on the potential use of salt resistant, non-edible plants for this purpose remains relatively underexplored. Data available on salt tolerance range, seed oil content, composition of fatty acid methyl esters (FAME) and engine performance parameters – Iodine Value (IV), Cetane Number (CN) and Saponification Number (SN) – of 20 salt-resistant plants were examined to assess their suitability for use as diesel engine fuel. Most of the test species were perennial from family Amaranthaceae, exhibiting high salt tolerance. The quantity of their seed oil ranged from 10–30% while nine species contained >25% oil. The SN, IV and CN values varied from 130–206, 29–156 and 38–81, respectively. Based on the above mentioned parameters, seven halophytic plant species – Salicornia fruticosa, Cressa cretica, Arthrocnemum macrostachyum, Alhagi maurorum, Halogeton glomeratus, Kosteletzkya virginica and Atriplex rosea – appear to be promising biodiesel candidates. These non-food plants which can grow using saline resources and have an oil composition suitable for engine efficiency are more salt resistant than Jatropha or other glycophytic feedstock to serve in a bioenergy farming system. Cultivation of such plants for biodiesel production has the additional advantage of reclaiming degraded lands with the environmental benefit of carbon sequestration.

Transcriptomic profiling of the salt-stress response in the halophyte Halogeton glomeratus.

BackgroundHalogeton glomeratus (H. glomeratus) is an extreme halophyte that is widely distributed in arid regions, including foothills, the Gobi desert of northwest China, and the marginal loess of Central Asia. However, research on the salt-tolerant mechanisms and genes of this species are limited because of a lack of genomic sequences. In the present study, the transcriptome of H. glomeratus was analyzed using next-generation sequencing technology to identify genes involved in salt tolerance and better understand mechanisms of salt response in the halophyte H. glomeratus.ResultsIllumina RNA-sequencing was performed in five sequencing libraries that were prepared from samples treated with 200 mM NaCl for 6, 12, 24, and 72 h and a control sample to investigate changes in the H. glomeratus transcriptome in response to salt stress. The de novo assembly of five transcriptomes identified 50,267 transcripts. Among these transcripts, 31,496 (62.66%) were annotated, including 44 Gene Ontology (GO) terms and 128 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Compared with transcriptomes from the control and NaCl-treated samples, there were 2,223, 5,643, 7,510 and 10,908 genes that were differentially expressed after exposure to NaCl for 6, 12, 24, and 72 h, respectively. One hundred and eighteen salt-induced genes were common to at least two stages of salt stress, and 291 up-regulated genes were common to various stages of salt stress. Numerous genes that are related to ion transport, reactive oxygen species scavenging, energy metabolism, hormone-response pathways, and responses to biotic and abiotic stress appear to play a significant role in adaptation to salinity conditions in this species. The detection of expression patterns of 18 salt-induced genes by quantitative real-time polymerase chain reaction were basically consistent with their changes in transcript abundance determined by RNA sequencing.ConclusionsOur findings provide a genomic sequence resource for functional genetic assignments of an extreme halophyte, H. glomeratus. We believe that the transcriptome datasets will help elucidate the genetic basis of this species’ response to a salt environment and develop stress-tolerant crops based on favorable wild genetic resources.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1373-z) contains supplementary material, which is available to authorized users.