Suaeda Salsa Research Articles

Description and characterization of three endophytic Bacillaceae from the halophyte Suaeda salsa: Paenalkalicoccus suaedae gen. nov., sp. nov., Cytobacillus suaedae sp. nov., and Bacillus suaedae sp. nov.

Three strains of members of the family Bacillaceae, which can inhibit the growth of some Gram-stain-positive strains, designated M4U3P1T, HD4P25T and RD4P76T, were isolated from Suaeda salsa halophytes in Baotou, Inner Mongolia, PR China. A phylogenetic analysis based on the 16S rRNA gene and the whole genome sequences revealed that HD4P25T clustered with Cytobacillus luteolus YIM 93174T with a similarity of 98.4 %, and RD4P76T shared the highest similarity of 16S rRNA gene with Bacillus mesophilus SA4T (97.5 %). M4U3P1T clustered with strains of genera Salipaludibacillus and Alkalicoccus based on whole-genome sequence analyses, but its 16S rRNA gene had the highest similarity to 'Evansella tamaricis' EGI 80668 (96.1 %). The average nucleotide's identity by blast (ANIb) and digital DNA-DNA hybridization (dDDH) values of the three isolated strains to their close relatives were well below the threshold value for identifying a novel species.On the basis of the phylogenetic, physiological and phenotypic results, Paenalkalicoccus suaedae gen. nov., sp. nov. [type strain M4U3P1T (=CGMCC 1.17076T=JCM 33851T)], Cytobacillus suaedae sp. nov. [type strain HD4P25T (=CGMCC 1.18651T =JCM 34524T)], and Bacillus suaedae sp. nov. [type strain RD4P76T (=CGMCC 1.18659T=JCM 34525T)] were proposed, respectively. All three species are ubiquitous in the bulk saline-alkaline soils, but only the species represented by strain RD4P76T was widely distributed in the rhizosphere soil, the above-ground part and the roots of S. salsa. The species represented by M4U3P1T can be detected in the roots of S. salsa, and rarely detected in the above-ground parts of S. salsa. The species represented by HD4P25T was rarely detected in the interior of S. salsa. The three strains could inhibit some of the Gram-stain-positive bacteria (i.e. members of the genera Planococcus, Zhihengliuella and Sanguibacter) in the saline-alkali soil. A genomic analysis of these three strains revealed that they can synthesize different antagonistic compounds, such as aminobenzoate and bacitracin or subtilisin.

Effects of simulated precipitation changes on plant community characteristics of wetland in the Yellow River Delta, China

Under the changing climate scenario, changes in precipitation regimes are expected to alter soil water and salinity conditions, with consequences on the characteristics of plant community in estuarine wetland. Here, we used a six-year (2015-2020) precipitation manipulation experiment to examine how plant community characteristics responded to precipitation changes in the Yellow River Delta. The results showed that soil electrical conductivity significantly decreased, while soil moisture significantly increased with increasing precipitation. Precipitation changes altered plant community composition. Increased precipitation reduced the absolute dominance of Suaeda glauca and Suaeda salsa, but increased that of Triarrhena sacchariflora and Imperata cylindrica. Shannon index and Margalef richness index of plant community significantly increased with increasing precipitation. Compared with the control, both decreased and increased precipitation decreased the plant community abundance, frequency and coverage. The treatment of 60% increased precipitation significantly decreased plant community frequency by 54.9%, while the 60% decreased precipitation, 40% decreased precipitation, 40% increased precipitation and 60% increased precipitation treatment significantly decreased plant abundance by 38.9%, 33.8%, 35.8% and 45.7%, respectively. The aboveground biomass significantly increased with increasing precipitation, but aboveground plant biomass under 60% increased precipitation treatment being lower than that reducing under 40% increased precipitation treatment, probably due to the negative effects of flooding stress. In addition, Margalef richness index had a significantly positive relationship with aboveground biomass. Aboveground biomass, Shannon diversity index, Margalef richness index, and Simpson diversity index were negatively related to soil electrical conductivity, and aboveground plant biomass was positively related to soil moisture. Our results revealed that precipitation changes regulate growth characteristics, species composition, and diversity of plant community by altering soil water and salinity conditions in a coastal wetland.

Proteomic analysis revealed modulations of carbon and nitrogen by arbuscular mycorrhizal fungi associated with the halophyte Suaeda salsa in a moderately saline environment

AbstractHalophytes can grow well in moderately salty habitats that restrain most plant growth. Arbuscular mycorrhizal fungi (AMF) can assist its host plants to effectively mitigate salinity stress. However, less information is available on the molecular mechanisms of AMF related to halophytes in adapting to moderate saline environments. A pot experiment was undertaken to detect the effects of AMF on the carbon (C), nitrogen (N) and phosphorus (P) concentrations in the halophyte Suaeda salsa which was grown at 100 mM NaCl and the underlying proteomic modulating mechanisms. The results proved that AMF decreased the N and P concentrations, increased the C, N and P accumulations and the C:N and C:P ratios. Proteomic analysis screened 581 differentially abundant proteins (DAP), which were mostly categorized in carbohydrate metabolism, energy metabolism and folding, sorting and degradation pathways. The enrichment analysis illuminated that the DAPs were assembled in 'carbon fixation in photosynthetic organisms,' 'nitrogen metabolism' and 'N‐glycan biosynthesis' pathways, which might be associated with the stoichiometric changes. The integrative proteomic and transcriptomic analysis detected 64 DAP whose regulations were concordant with those of the corresponding differentially expressed genes. Furthermore, these proteins were enriched in 'carbon fixation in photosynthetic organisms' and some amino acid metabolism pathways. The modulations of these pathways might be correlated with C and N allocations and plant growth in moderate saline conditions. The study supplements the comprehension of the roles of AMF in halophytes grown in saline ecosystems.

Variation in Bacterial Community Structures and Functions as Indicators of Response to the Restoration of Suaeda salsa: A Case Study of the Restoration in the Beidaihe Coastal Wetland.

Microbes play an essential role in the restoration of degraded coastal wetlands. However, few studies have focused on the role of key bacteria in the restoration process. Here, Suaeda salsa was planted to recover the biodiversity in the degraded Beidaihe coastal wetland. We monitored omics and soil environmental factors to understand the complex relationship between the bacterial community and wetland health during the restoration period. After planting S. salsa in the degraded area, the soil quality was improved in the later stage of restoration (LPR). Bacterial α-diversity increased with restoration and was positively correlated with TOC. Proteobacteria is the dominant bacterial phylum during the restoration period, and Bacteroidetes, Planctomycetes, Gemmatimonadetes, and Acidobacteria were sensitive to the planting restoration. Random forest analysis picked 30 key OTUs, showing the key bacterial variation of successful restoration. The result indicated that the sum of the relative abundances of key bacterial OTUs was more than 2% in the health wetland. The β-diversity showed that the growth of S. salsa reshaped the soil bacterial community structure and function in the LPR, which recovered to the level in the control area. Putative biogeochemical functions showed that symbionts and aromatic compound degradation were dominant bacterial functions in the growth period of S. salsa. Our study proposed a new indicator to assess wetland health and the planting restoration of S. salsa increased bacteria groups with the ability of symbionts and aromatic compound degradation in the Beidaihe coastal wetland. This study expanded our knowledge of coastal wetland restoration and its ecological contributions.

Teaching reform and practice of bioengineering comprehensive experiment based on virtual simulation technology

Bioengineering majors require students to acquire excellent abilities of thinking and analyzing complex problems and have high requirements for students' comprehensive practical skills. Because of the professional characteristics, it is necessary to develop students' abilities to solve complex problems via the teaching of a series of experiments. Therefore, it is particularly important to reform the traditional experiment teaching for students majoring in bioengineering to improve the teaching quality, which have great significance for the cultivation of comprehensive talents. In this study, with the advantages of geographical location and resources to cultivate application-oriented innovative talents, the course group of Comprehensive Experiment of Bioengineering has designed the course based on virtual simulation technology in Binzhou University. Taking the experiment of extraction and bioactivity analysis of Suaeda salsa (growing in the Yellow River Delta) polysaccharide in fermentation as a case, we studied the course design idea, experimental process, teaching method and result analysis, and have improved the teaching performance. This case analysis provides new ideas and content reference for the teaching reform of similar courses.

Distribution and Influencing Factors of Metals in Surface Soil from the Yellow River Delta, China

To study metal enrichment and identify the influencing factors, 106 surface soils were collected in the Yellow River delta, including ten vegetation types. Concentrations of 10 different metals, including As, Cd, Cr, Ni, Cu, Pb, Zn, Mn, Al, Fe, and physicochemical properties pH, salinity, particle size were detected. The pH value was 7.35~9.17, and the salinity was in the range of 0.01~2.00%. The average value of silt was 76.18%, which was the main particle size for 99% of the samples. The mean concentrations of As, Cd, Cr, and Ni were higher than the background value of Shandong Province or the background value of yellow soil in China. A higher concentration of Fe occurred in Phragmites australis (mean concentration 2.50%) and paddy field. The concentrations of Cd, Cr, Ni, Cu, Pb and Zn were lower in the Suaeda salsa soil. The Nemerow pollution index indicated that 79% of all samples showed low-level metal pollution, and 7% of all samples showed moderate-level metal pollution. In the areas with higher salinity, the concentrations of As were higher, while the concentrations of Cd and Ni were lower. The correlation analysis showed that with increasing pH, the concentrations of As and Zn decreased significantly. The metal concentrations had a significant positive correlation with clay, except for As.

Nitrogen-Salt Interaction Adjusts Root Development and Ion Accumulation of the Halophyte Suaeda salsa.

Nitrogen (N) application might exert a great impact on root (biomass, length) distribution, which possibly contributes to ion and nutrient uptakes. Here, we address the effects of N application on these characteristics to detect how N improves its salt tolerance. Suaeda salsa was subjected to four salt levels (0.5, 1.0, 1.5, and 2.0%) and three N treatments (-N: 0, 0.25, and 0.50 g·kg−1) in soil column experiments. The N applications performed a “dose effect” that significantly enhanced the growth of Suaeda at low salt levels, while negative effects were displayed at high salt levels. Moderate N markedly benefited from and uptake, which was approximately 111 mg and 146 mg per plant at a salt level of 1.0%. Exposure to a certain N application significantly enhanced topsoil root length at salt levels of 0.5% and 1.0%, and it was higher by 0.766 m and 1.256 m under N50 treatment than that under N0 treatment, whereas the higher salt levels accelerate subsoil root growth regardless of N treatment. Therefore, its interactive effects on root development and ion uptake were present, which would provide further theoretical basis for improving saline soil amelioration by N application. Regression analysis always showed that topsoil root length generated more positive and significant influences on ion uptake and vegetative growth than total root length. The results suggested that N application is beneficial to salt tolerance by altering root allocation so as to raise its elongation and gather more ions for halophyte in the topsoil.

Cell Wall Components and Extensibility Regulate Root Growth in Suaeda salsa and Spinacia oleracea under Salinity.

Understanding the role of root cell walls in the mechanism of plant tolerance to salinity requires elucidation of the changes caused by salinity in the interactions between the mechanical properties of the cell walls and root growth, and between the chemical composition of the cell walls and root growth. Here, we investigated cell wall composition and extensibility of roots by growing a halophyte (Suaeda salsa) and a glycophyte (Spinacia oleracea) species under an NaCl concentration gradient. Root growth was inhibited by increased salinity in both species. However, root growth was more strongly reduced in S. oleracea than in S. salsa. Salinity reduced cell wall extensibility in S. oleracea significantly, whereas treatment with up to 200 mM NaCl increased it in S. salsa. Meanwhile, S. salsa root cell walls exhibited relatively high cell wall stiffness under 300 mM NaCl treatment, which resist wall deformation under such stress conditions. There was no decrease in pectin content with salinity treatment in the cell walls of the elongation zone of S. salsa roots. Conversely, a decrease in pectin content was noted with increasing salinity in S. oleracea, which might be due to Na+ accumulation. Cellulose content and uronic acid proportions in pectin increased with salinity in both species. Our results suggest that (1) cell wall pectin plays important roles in cell wall extension in both species under salinity, and that the salt tolerance of glycophyte S. oleracea is affected by the pectin; (2) cellulose limits root elongation under saline conditions in both species, but in halophytes, a high cell wall content and the proportion of cellulose in cell walls may be a salt tolerance mechanism that protects the stability of cell structure under salt stress; and (3) the role of the cell wall in root growth under salinity is more prominent in the glycophyte than in the halophyte.

The behavior of birds digging pits and foraging in the degraded coastal wetland promotes the restoration of vegetation

Birds are a very important part of the coastal wetland ecosystem, and they are also ecosystem engineers who can affect the abiotic environment and biological processes through their own behavior. Understanding the ecosystem engineering effect of birds in the coastal wetland ecosystem plays an important role in the ecological restoration of coastal wetlands. Through field investigation, the effects of pit digging and foraging behavior of coastal birds led by Grus grus and Anas poecilorhyncha on the topography and soil environmental physical and chemical indicators in the vegetation degradation area were studied, so as to promote the restoration of Suaeda salsa vegetation. The results showed that birds’ digging and foraging behavior in the degraded vegetation area changed the micro topography and soil environment in the degraded area, resulting in a significant decrease in soil hardness and soil salinity, while soil moisture content and soil carbon and nitrogen nutrition index were significantly higher than those in the degraded flat area without the influence of birds; in addition, the pit micro terrain environment improved by bird activities can significantly improve the seed retention, seedling colonization and adult survival of Suaeda salsa, and effectively promote the restoration of Suaeda salsa in the vegetation degradation area. Inspired by the change of microtopography by birds to promote vegetation restoration, it is proposed that we can try to artificially simulate and transform the microtopography environment in the degraded area, and promote the vegetation restoration in the degraded area of coastal wetlands through human intervention, which has important guiding significance for the ecological restoration of coastal wetlands.

Soil characteristics and ecological thresholds of Suaeda salsa wetlands

ABSTRACT Suaeda salsa is an annual euhalophyte in estuarine wetlands. Soil properties of wetlands have an important influence on S. salsa growth. Therefore, the soil ecological thresholds is valuable for the restoration of degraded S. salsa wetlands. The objectives of this present study were to analyze the soil physicochemical properties and evaluate the soil ecological thresholds in the typical degraded areas for S. salsa growth. Soil text components became coarser with increased sand contents and less clay contents, as the higher degree of wetland degradation. Meanwhile, the salt contents in different soil depths gradually increased with the increased degree of degradation of wetlands. Evident changes in soil water content, organic matter content, and cations concentrations were not observed, while the concentrations of these factors were higher in the soil layer of 0–10 cm than those in the 20–30 cm. The soil pH in the 0–10 cm soil layer was lower than that in the 20–30 cm. The content of the three available nutrients did not change evidently with the increasing degree of degradation. The optimum thresholds of soil salinity and water content were 7.073–16.613 g/kg and 31.8–63.2%, respectively.

Effects of Spartina alterniflora invasion on the benthic invertebrate community in intertidal wetlands

AbstractExotic species invasions have profound effects on native ecosystems, with the ecological effects of non‐native plants being especially pervasive. We investigated the impacts of a plant invasion on benthic invertebrate assemblages in intertidal wetlands of the Yellow River Delta, comparing benthic communities associated with exotic Spartina alterniflora against those associated with native plants (Tamarix chinensis, Suaeda salsa, and mudflat). Our study surprisingly found that the density, diversity, and richness of benthic invertebrates associated with S. alterniflora were higher than with native habitats. Multivariate analysis also revealed that the structure of benthic invertebrates in S. alterniflora habitats was different than in T. chinensis and mudflat habitats. The structure of invertebrates associated with the invasive S. alterniflora and native S. salsa was more similar, although the dominant species differed. Indicator species analyses indicated that each habitat was characterized by unique taxa. S. alterniflora invasion increased the beta diversity of the community, with the species turnover component being of most importance. Mollusks were most likely to be influenced by Spartina invasions. Given the extent of the S. alterniflora invasion in the Yellow River Delta, altered benthic invertebrate communities will likely have important implications for the ecology of the intertidal wetland ecosystems and deserve increased attention.

Positive effects of NaCl on the photoreaction and carbon assimilation efficiency in Suaeda salsa

Suaeda salsa L. is a typical euhalophyte and can be used as a model halophyte for research on salt tolerance. S. salsa seedlings were cultured with 0, 200 and 500 mM NaCl for 2 and 14 days. The results revealed that 200 mM NaCl promoted the shoot dry weight, net photosynthetic rate (Pn), chlorophyll content, electron transfer rate, NADPH level, activities of ferredoxin-NADP oxidoreductase, ribulose-1, 5-bisphosphate carboxylase (Rubisco) and Rubisco activase, particularly the Rubisco activity, chlorophyll content and Pn, when the seedlings were treated with 200 mM NaCl for 14 days. Moreover, 500 mM NaCl had no adverse effects on those parameters. In conclusion, NaCl improved the photoreaction and carbon assimilation efficiency of S. salsa. The increased Rubisco activity and chlorophyll content may play critical roles in the enhancement of the photosynthetic efficiency in S. salsa under saline conditions, which may explain why S. salsa can produce the highest biomass at approximately 200 mM NaCl.

Comparison of biochar properties from 5 kinds of halophyte produced by slow pyrolysis at 500 \xb0C

Glycophyte biomass-derived biochars are currently concerned in most studies. However, little attention is given to the characteristics of halophyte-derived biochars. In this study, five typical halophytes of euhalophytes (Suaeda altissima, Suaeda salsa, and Kalidium foliatum), recretohalophytes (Phragmites australis), and pseudohalophytes (Tamarix chinensis) which are widely distributed in the arid and semiarid regions of northwestern China were selected for producing biochars with a slow pyrolysis process at 500 °C for 1 h. The harvested biochars were characterized in elemental content, pores, surface area, and surface charges, and then their potential value as a soil conditioner was evaluated. The results showed that the halophyte-derived biochars had variable ash and Na+ contents, ranging from 7.26 to 23.64% and 1.06 to 33.93 g kg−1 respectively. The EC value of the biochars ranged from 1.76 to 23.45 mS cm−1. The biochar derived from Suaeda altissima had a very low specific surface area (SSA), 3.50 m2 g−1, while that derived from Phragmites australis (BPA) had a very high SSA, 344.02 m2 g−1. All the biochars carried both positive and negative charges. Kalidium foliatum biochar (BKF) possessed more negative charges, while Suaeda altissima biochar (BSA) contained more positive charges. In general, the halophyte biochars had a higher ash content and lower point of zero net charge (PZNC) value, compared with the biochars derived from glycophytes, which would imply their higher potential value as an acidic soil conditioner.

Plant Adaptability and Vegetation Differentiation in the Coastal Beaches of Yellow-Bohai Sea in China.

To identify the key soil factors influencing the vegetation differentiation in the coastal tidal flats of the Yellow−Bohai Sea in China, this study investigated the corresponding relationship between the Spartina alterniflora (SA), Suaeda salsa (SS), and Phragmites australis (PA) communities and their respective soil factors with published data, and combined the ecological strategy for analysis. The results showed a corresponding relationship between community and soil factors. The SA community had a lower bulk density (BD) and higher soil total nitrogen (TN), and the SS community was the opposite, while the PA community had the lowest salinity and higher TN. BD, salinity and TN acted as the main soil factors driving vegetation differentiation, but the explained proportion of the three factors to vegetation differentiation changed by season and region. Considering that higher TN facilitates the competitors, salinity represents the environmental stresses, and BD is positively related to the frequency of perturbation in the specific habitat in the study area, SA, SS and PA could be recognized as C–S, S–R and C strategic species to some extent. It is likely that some coexistent mechanisms for invasive and local species will be developed, especially the SS community which seriously shrunk recently but served as an important habitat for waterfowls in tidal flat habitats.

Responses of soil nutrient contents and eco-stoichiometric characteristics to fiddler crab activities in coastal wetland of the yellow river delta

The four typical wetlands of Phragmites australis wetland (TPa), Tamarix chinensis wetland (Tc), Suaeda salsa wetland (Ss) and Spartina alterniflora wetland (Sa) in the Yellow River Delta were selected to clarify the spatial heterogeneity of soil nutrients and their ecological stoichiometric characteristics under fiddler crab activities. The results showed that soil particle size, soil salinity and pH in Tc, TPa and Ss were greatly changed by fiddler crab activities. The averaged contents of TOC and TN in wetlands with fiddler crab activities (FC) were higher than those in wetlands without fiddler crab activities (CK). The averaged NH4+-N contents of FC group in Tc, Ss and Sa were 93.42%, 52.14% and 20.05% higher than those of CK group (p<0.05), respectively. The averaged NO3−-N contents of Tc and Sa in FC group were 89.79% and 167.70% higher than those of CK group (p<0.01), respectively. The variation tendency of C/N and C/P in four wetland types were greatly similar with the TOC, and N/P was similar with TN. Multi-ANOVA results showed that soil carbon and nitrogen were significantly influenced by fiddler crab activities and wetland types (p<0.05). The PCA and RDA analysis results indicated that the bioturbation from fiddler crab made the influencing factors of nutrient elements diversified. The fiddler crab activities were favorable to the soil nutrients accumulation and could reduce the nitrogen limitation of coastal ecosystem. Our results should be of importance to insight the biogeochemical process of soil nutrient elements differentiation by fiddler crab activities in coastal wetlands.

Transcriptomic analysis reveals the molecular mechanisms of arbuscular mycorrhizal fungi and nitrilotriacetic acid on Suaeda salsa tolerance to combined stress of cadmium and salt

Halophytes are dominant plants in the phytoremediation of heavy metal contaminated saline soils. Arbuscular mycorrhizal (AM) fungi can improve plant abiotic stress tolerance and chelating agents nitrilotriacetic acid (NTA) can alleviate heavy metal stress. However, the combined effects and mechanisms of two amendments on halophytes grown in heavy metal contaminated saline soils are largely unknown. Pot experiment was conducted to explore the molecular mechanisms of Funneliformis mosseae (Fm) and NTA (10 mmol·kg−1) on Suaeda salsa tolerance to combined stress of Cd (5 mg·kg−1) and NaCl (2.5 g·kg−1). The results showed that AM fungi and NTA promoted growth of S. salsa, increased accumulations of Na+, Cd and mineral elements, but decreased Na+, Cd and malondialdehyde (MDA) concentrations in shoots under combined stress. Transcriptomic analysis presented various regulation pathways of the single or combined application of AM fungi and NTA on S. salsa. The identified differentially expressed genes (DEGs) in (Fm+NTA)/CK were mainly involved in antioxidant defense, osmoregulation, and photosynthesis; the DEGs in (Fm+NTA)/Fm were related to the maintenance of the cell membrane integrity and plant abiotic stress tolerance; and the DEGs in (Fm+NTA)/NTA were related to the enhancement ability of secondary cell wall synthesis and transcription factor. Our study provides new insights into the molecular mechanisms of AM fungi and NTA on halophytes tolerance to combined stress of heavy metal and salt.

Plant-plant interactions of Phragmites australis and Suaeda salsa as mediated by combined influences of salinity and tidal level changes

Plant-plant interactions of Phragmites australis and Suaeda salsa as mediated by combined influences of salinity and tidal level changes

Effects of wetland plant biochars on heavy metal immobilization and enzyme activity in soils from the Yellow River estuary.

The purpose of this study was to assess the effects of wetland plant biochars on the enzyme activity in heavy metal contaminated soil. The biochars were produced from Phragmites australis (PB), Suaeda salsa (SB), and Tamarix chinensis (TB) under different pyrolysis temperatures and times. The detected pyrolysis products showed that the ash, pH, electrical conductivity, and carbon content of the biochars increased significantly, while the production rate of the biochars decreased with increasing pyrolysis temperature and time. The results of the adsorption experiments indicated that biochar addition could effectively reduce the concentration of Pb and/or Cd in the Pb2+/Cd2+ single or mixed solutions, but the Pb2+ and Cd2+ in the mixed solution indicated a competitive adsorption. A 30-day incubation experiment was conducted using salt marsh soil amended with different biochar application rates to investigate the short-term effects of biochar addition on Pb and Cd immobilization. The PB and SB significantly immobilized Pb within the first 15days, but Pb remobilized within the next 15-day period. In contrast, TB addition did not significantly fix Pb. Moreover, biochar addition promoted the conversion of Cd from the residue to the less immobile fractions. The addition of three types of plant biochar had no significant effect on the urease activity in wetland soil but significantly increased soil sucrase activity. PB and SB significantly promoted catalase activity, while TB significantly inhibited soil catalase activity. According to the adsorption effect, the fixation effect, and the promotion of enzyme activities, the Suaeda salsa biochars are suitable for the remediation of heavy metal pollution in wetland soils.

Metabolic differences of two constructive species in saline-alkali grassland in China

BackgroundSalinization of soil is an urgent problem that restricts agroforestry production and environmental protection. Substantial accumulation of metal ions or highly alkaline soil alters plant metabolites and may even cause plant death. To explore the differences in the response strategies between Suaeda salsa (S. salsa) and Puccinellia tenuiflora (P. tenuiflora), two main constructive species that survive in saline-alkali soil, their metabolic differences were characterized.ResultMetabolomics was conducted to study the role of metabolic differences between S. salsa and P. tenuiflora under saline-alkali stress. A total of 68 significantly different metabolites were identified by GC-MS, including 9 sugars, 13 amino acids, 8 alcohols, and 34 acids. A more detailed analysis indicated that P. tenuiflora utilizes sugars more effectively and may be saline-alkali tolerant via sugar consumption, while S. salsa utilizes mainly amino acids, alcohols, and acids to resist saline-alkali stress. Measurement of phenolic compounds showed that more C6C3C6-compounds accumulated in P. tenuiflora, while more C6C1-compounds, phenolic compounds that can be used as signalling molecules to defend against stress, accumulated in S. salsa.ConclusionsOur observations suggest that S. salsa resists the toxicity of saline-alkali stress using aboveground organs and that P. tenuiflora eliminates this toxicity via roots. S. salsa has a stronger habitat transformation ability and can provide better habitat for other plants.

The Effects of Suaeda salsa/Zea mays L. Intercropping on Plant Growth and Soil Chemical Characteristics in Saline Soil

Halophytes possess the capacity to uptake high levels of salt through physiological processes and their root architecture. Here, we investigated whether halophyte/non-halophyte intercropping in saline soil benefits plant growth and contains root-dialogue between interspecific species. Field and pot experiments were conducted to determine the plant biomasses and salt and nutrient distributions in three suaeda (Suaeda salsa)/maize (Zea mays L.) intercropping systems, set up by non-barrier, nylon-barrier, and plastic-barrier between plant roots. The suaeda/maize intercropping obviously transferred more Na+ to the suaeda root zone and decreased salt and Na+ contents. However, the biomass of the non-barrier-treated maize was significantly lower than that of the nylon and plastic barrier-treated maize. There was lower available N content in the soil of the non-barrier treated groups compared with the plastic barrier-treated groups. In addition, the pH was lower, and the available nutrient content was higher in the nylon barrier, which suggested that rhizospheric processes might occur between the two species. Therefore, we concluded that the suaeda/maize intercropping would be beneficial to the salt removal, but it caused an adverse effect for maize growth due to interspecific competition, and also revealed potential rhizospheric effects through the role of roots. This study provides an effective way for the improvement of saline land.