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Launaea sarmentosa is a valuable medicinal plant with adaptability in saline areas, but it is still unclear how it responds to salinity. For the first time, the present study examined the plant's changes under different soil salinities generated by 50, 100, 200, and 400 mM NaCl in order to elucidate its responses in terms of growth, photosynthesis, water uptake, osmotic adjustment, ion homeostasis, and oxidative stress defense to salinity. The results showed that the plant's growth was enhanced by 50 mM NaCl with an 18.07% increase in dry biomass compared to the control, whereas higher salinity levels reduced its growth with a 6.39–54.85% decrease in dry biomass. The plant's growth response indicates that it had tolerance to salinity levels up to 400 mM NaCl. The accumulation of photosynthetic pigments, including chlorophylls (a + b) and carotenoids, was enhanced under salinity, except for a reduced accumulation under 400 mM NaCl. Relative water content decreased while proline content increased in the salt-stressed plants. Moreover, the salt-stressed plants reduced their K+ and NO3− content along with increases in Na+ and Cl− content. The high salt stress level also caused oxidative stress in the plants, which was revealed through the accumulation of malondialdehyde and hydrogen peroxide content. In addition, the salt-stressed plants had increased total phenolic content and the activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase. These physiological and biochemical changes suggest that L. sarmentosa evolved adaptive mechanisms in photosynthesis, osmotic adjustment, ion homeostasis, and antioxidant defense for growing under salt stress. [ABSTRACT FROM AUTHOR]

Abstract Grangea maderaspatana is a valuable medicinal plant growing in salt-affected areas, but its tolerance capability, physiological and biochemical responses to salinity is still unclear. To understand these traits, this study examined effects of salinity at different levels (50-400 mM NaCl) on plant growth and its responses. The results shown that the plant’s dry biomass decreased with increasing salinity levels of 100-400 mM NaCl, but its growth was maintained at 400 mM NaCl level with a dry biomass equal to 0.45 times that of the control, indicating that G. maderaspatana had a tolerance ability to high salinity. The plant also had adaptive responses to the salinity. The content of leaf chlorophylls and carotenoids were retained, even enhanced by 50-200 mM NaCl, suggesting a high adaptation of photosynthesis. Proline, Na+, and Cl- was highly accumulated while the accumulation of K+ and NO3 - was maintained with 200-400 mM NaCl, indicating that the plant had adaptive mechanisms for osmotic adjustment and ion homeostasis. Antioxidative activities of catalase, superoxide dismutase, and peroxidase were enhanced by the salinity. These findings are useful information for understanding salt tolerance mechanisms and for utilization of this medicinal plant in saline agriculture.

Halophytes not only tolerate to salinity, but also promote their growth under a suitable saline condition (referred to as halophilism). Tetagonia tetragonioides is a halophyte that its growth is promoted by NaCl salinity up to 100 mM, but the mechanism of halophilism has not been elucidated. The present study examined responses in the plant’s growth, photosynthesis, and water uptake under the halophilism condition. The results the fresh and dry biomass were increased by 35.86 and 37.04% compared to the plant grown without salt, respectively. The growth enhancement of plant was contributed by the growth of both shoots and roots. Leaf chlorophyll content was also increased 1.10 times under the halophilism condition. Relative water content was not significantly increased, but proline content was increased 15.93 – 52.31 times with increasing salinity levels. These results suggest mechanisms that regulated photosynthesis and water uptake for the halophilism.

Utilizing salt-tolerant plants is a cost-effective strategy for agricultural production on salinized land. However, little is known about the mechanism of dandelion (Taraxacum mongolicum Hand.-Mazz.) in response to saline stress and caffeic acid biosynthesis. We investigated the morphological and physiological variations of two dandelions, namely, "BINPU2" (dandelion A) and "TANGHAI" (dandelion B) under gradient NaCl concentrations (0, 0.3%, 0.5%, 0.7%, and 0.9%), and analyzed potential mechanisms through a comparison analysis of transcriptomes in the two dandelions. Dandelion A had a high leaf weight; high ρ-coumaric acid, caffeic acid, ferulic acid, and caffeoyl shikimic acid contents; and high activities of POD and Pro. The maximum content of four kinds of phenolic acids mostly occurred in the 0.7% NaCl treatment. In this saline treatment, 2468 and 3238 differentially expressed genes (DEGs) in dandelion A and B were found, of which 1456 and 1369 DEGs in the two dandelions, respectively, showed up-regulation, indicating that more up-regulated DEGs in dandelion A may cause its high salt tolerance. Further, Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that dandelion salt response and caffeic acid metabolism were mainly enriched in the phenylpropanoid biosynthesis pathway (ko00940) and response to ethylene (GO: 0009723). The caffeic acid biosynthesis pathway was reconstructed based on DEGs which were annotated to PAL, C4H, 4CL, HCT, C3′H, and CSE. Most of these genes showed a down-regulated mode, except for parts of DEGs of 4CL (TbA05G077650 and TbA07G073600), HCT (TbA03G009110, TbA03G009080, and novel.16880), and COMT (novel.13839). In addition, more up-regulated transcription factors (TFs) of ethylene TFs in dandelion A were found, but the TFs of ERF104, CEJ1, and ERF3 in the two dandelions under saline stress showed an opposite expression pattern. These up-regulated genes could enhance dandelion salt tolerance, and down-regulated DEGs in the caffeic acid biosynthesis pathway, especially CSE (TbA08G014310) and COMT (TbA04G07330), could be important candidate genes in the synthesis of caffeic acid under saline stress. The above findings revealed the potential mechanisms of salt response and caffeic acid metabolism in dandelion under saline stress, and provide references for salt-tolerant plant breeding and cultivation on saline–alkali land in the future. [ABSTRACT FROM AUTHOR]

Launaea sarmentosa is a valuable medicinal plant with adaptability in saline areas, but it is still unclear how it responds to salinity. For the first time, the present study examined the plant’s changes under different soil salinities generated by 50, 100, 200, and 400 mM NaCl in order to elucidate its responses in terms of growth, photosynthesis, water uptake, osmotic adjustment, ion homeostasis, and oxidative stress defense to salinity. The results showed that the plant’s growth was enhanced by 50 mM NaCl with an 18.07% increase in dry biomass compared to the control, whereas higher salinity levels reduced its growth with a 6.39–54.85% decrease in dry biomass. The plant’s growth response indicates that it had tolerance to salinity levels up to 400 mM NaCl. The accumulation of photosynthetic pigments, including chlorophylls (a + b) and carotenoids, was enhanced under salinity, except for a reduced accumulation under 400 mM NaCl. Relative water content decreased while proline content increased in the salt-stressed plants. Moreover, the salt-stressed plants reduced their K+ and NO3− content along with increases in Na+ and Cl− content. The high salt stress level also caused oxidative stress in the plants, which was revealed through the accumulation of malondialdehyde and hydrogen peroxide content. In addition, the salt-stressed plants had increased total phenolic content and the activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase. These physiological and biochemical changes suggest that L. sarmentosa evolved adaptive mechanisms in photosynthesis, osmotic adjustment, ion homeostasis, and antioxidant defense for growing under salt stress.

Salinty and alkali are the serious stress in arid and semiarid area, which has a bad effect on plant growth. It is necessary for us to explore the variety of microbial community and the activity of enzyme in rhizosphere of Pennisetum giganteum(giant juncao)under saline-alkali environment. As a result, we set up the experiment with seven different kinds of saline-alkali concentrations, analyze the difference significance and correlation of physiological data under different saline-alkali concentrations with the method of SPSS, and analyzed the diversities of microbial communities with the method of Illumina high-throughput sequencing. The results were as follows:(1)The composition of microbial communities in rhizosphere soil of giant juncao differed at different saline-alkali stresses; The dominant groups were Sordariomycetes(68.5%), Eurotiomycetes(16.3%), Chloroflexia(8.5%), Bacteroidia(13.5%), Gemmatimonadetes(5.6%)and δ-Proteobacteria(3.7%)at the 12‰ saline-alkali concentration; The relative abundance of the Dothideomycetes(27.7%)and Anaerolineae(2.4%)was sharply reduced to 2.5% and 0.007% when the saline-alkali concentration increased from 6‰ to 12‰; The Chao and Shannon indexes of the rhizosphere microbial community of giant juncao decreased with increasing saline-alkali concentration, and were significantly correlated with soil saline-alkali concentration(P<0.01).(2)The low concentration of saline-alkali stress had a positive effect on activities of urease, polyphenol oxidase and alkaline phosphatase in rhizophere soil of giant juncao, but activities of polyphenol oxidase, alkaline phosphatase and sucrase were inhibited when the saline-alkali concentration of soil exceeded 8‰; After planting giant juncao, the content of soil organic matter increased significantly(P<0.05)and the saline-alkali concentration were reduced significantly(P<0.05); The neutralizing ability to soil alkalinity gradually weakened with the increasing saline-alkali concentration, and the neutralizing ability of soil salinity gradually weakened when the concentration exceeded to 8‰; When the saline-alkali concentration was 6‰, the production of giant juncao was the highest and the soil had higher contents of available nutrients and organic matter. The research indicates that growing giant juncao is beneficial to improving the fertility of saline-alkali soil by adjusting the enzyme concentration to better adapt to the medium and low concentration saline-alkali soil environment, and producing the corresponding dominant flora to adapt to the environment in different degrees of saline-alkali soil. [ABSTRACT FROM AUTHOR]

Dielectric properties of saline soil (SS) and Salicornia perennans Willd (SPW) were measured at a frequency of 1.41 GHz using a bridge-type laboratory setup and different volume fractions of water in the samples. Experimental dependences of the refractive index and absorption factor on a volume fraction of water were approximated by piecewise-broken lines with break two points corresponding to maximum volume fractions of bound water in the samples. In the SS and SPW, we identified three categories of water with different dielectric properties. Using the empirical dependences refractive index, absorption factor on a volume fraction of water and the refraction model, dielectric parameters of bound and free water from the samples were calculated. Based on the experimental data and model representations, the possibility of using the unified approach to the description of dielectric properties of SS and SPW was discussed. To describe the dependences of the refractive index and absorption factor of SS and SPW volume fraction of water, the refraction model is used. [ABSTRACT FROM AUTHOR]

ABSTRACT Salinity is an important abiotic stress affecting plant growth. We have known that plants can recruit beneficial microbes from the surrounding soil. However, the ecological functions of the core microbiome in salt-tolerant plants, together with their driving factors, remain largely unexplored. Here, we employed both amplicon and shotgun metagenomic sequencing to investigate the microbiome and function signatures of bulk soil and rhizocompartment samples from three salt-tolerant plants (legumes Glycine soja and Sesbania cannabina and nonlegume Sorghum bicolor). Strong filtration effects for microbes and functional genes were found in the rhizocompartments following a spatial gradient. The dominant bacteria belonged to Ensifer for legumes and Bacillus for S. bicolor. Although different salt-tolerant plants harbored distinct bacterial communities, they all enriched genes involved in cell motility, Na+ transport, and plant growth-promoting function (e.g., nitrogen fixation and phosphate solubilization) in rhizoplane soils, implying that the microbiome assembly of salt-tolerant plants might depend on the ecological functions of microbes rather than microbial taxa. Moreover, three metagenome-assembled genomes affiliated to Ensifer were obtained, and their genetic basis for salt stress alleviation were predicted. Soil pH, electrical conductivity, and total nitrogen were the most important driving factors for explaining the above microbial and functional gene selection. Correspondingly, the growth of an endophyte, Ensifer meliloti CL09, was enhanced by providing root exudates, suggesting that root exudates might be one of factors in the selection of rhizosphere and endosphere microbiota. Overall, this study reveals the ecological functions of the populations inhabiting the root of salt-tolerant plants. IMPORTANCE Salinity is an important but little-studied abiotic stressor affecting plant growth. Although several previous reports have examined salt-tolerant plant microbial communities, we still lack a comprehensive understanding about the functional characteristics and genomic information of this population. The results of this study revealed the root-enriched and -depleted bacterial groups, and found three salt-tolerant plants harbored different bacterial populations. The prediction of three metagenome-assembled genomes confirmed the critical role of root dominant species in helping plants tolerate salt stress. Further analysis indicated that plants enriched microbiome from soil according to their ecological functions but not microbial taxa. This highlights the importance of microbial function in enhancing plant adaptability to saline soil and implies that we should pay more attention to microbial function and not only to taxonomic information. Ultimately, these results provide insight for future agriculture using the various functions of microorganisms on the saline soil.

ABSTRACT Soil salinization is one of the major land degradation processes that decreases soil fertility and crop production worldwide. In this study, a long-term coastal saline soil remediation experiment was conducted with three salt-tolerant plant species: Lycium chinense Mill. (LCM), Tamarix chinensis Lour. (TCL), and Gossypium hirsutum Linn. (GHL). The three plant species successfully remediated the saline soil but showed different efficacies. The archaeal, bacterial, and fungal communities in barren soil and in four rhizocompartments (distal-rhizosphere soil, proximal-rhizosphere soil, rhizoplane, and endosphere) of the three plant species were assessed. All three plant species significantly decreased the richness of the archaeal communities but increased that of the bacterial and fungal communities in both the rhizosphere and rhizoplane compared with those in the barren soil. The archaeal and bacterial community structures were strongly influenced by the rhizocompartment, while specific fungal communities were recruited by different plant species. The microbial taxa whose abundance either increased or decreased significantly during remediation were identified. Soil electrical conductivity (EC) was identified as the main factor driving the variation in microbial community composition between the remediated and barren soil, and total nitrogen (TN), total carbon (TC), and available potassium (AK) were the main factors driving the differences among plant species. This report provides new insights into the responses of the root zone microbial communities of different salt-tolerant plant species during phytoremediation. IMPORTANCE Despite knowing that phytoremediation by salt-tolerant plants is an effective technology for ameliorating saline soils and that microorganisms contribute significantly to plant stress tolerance and soil fertility, we still lack a comprehensive understanding of how microbes respond to the growth of salt-tolerant plants and the subsequent decline in soil salinity. The results of this study revealed different response patterns among bacterial, archaeal, and fungal communities and indicated that the decline in archaeal abundance might be a sign of successful remediation of coastal saline soils. The recruitment of specific fungal communities by different plant species indicated the importance of fungi in plant species-specific remediation functions. We also identified the taxa that may play key roles during remediation, and these taxa could potentially be used as indicators of phytoremediation. Overall, these findings highlight the importance of microbes in the phytoremediation of saline soil and suggest that the mechanisms involved are plant species specific.

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A series of investigations was conducted to treat saline domestic sewage using constructed wetlands. Twelve emergent plant species were planted in experimental units and fed with saline domestic sewage. All species were classified into three clusters using cluster analysis based on the average values of relative growth rate, nutrient uptake, root biomass and activity. The species of Cluster I, includingCanna indica,Phragmites australisandScirpus validus, had strong potential for the purification. The above plants were employed again to treat saline domestic sewage under different influent salinities concentrations. For the influent salinity of 0.5, 1.0 and 1.5%, average treatment performances of planted units were found to be 61.5–70.5% for COD, 59.3–68.4% for–N, 61.9–70.4% for TN and 40.4–47.3% for TP. With increasing influent salinity to 2.0%, the removal efficiencies were dropped significantly. It was similar to the change of the soil enzyme activity in the experiment units. Activities of urease and cellulase declined significantly when influent salinity increased to 2.0%. The lower soil enzyme activity in the treatments receiving wastewater at 2.0% indicated that saline domestic sewage had an adverse effect on microbial activities. [ABSTRACT FROM PUBLISHER]

To our knowledge there has been no research on Aeluropus littoralis as a halophyte plant, when grown in soil contaminated with cadmium (Cd). Hence, the ability of A. littoralis to take up Cd and some nutrients was investigated in a pot experiment. Five levels of soil Cd concentration were tested (15, 30, 60, 120 and 240 mg Cd kg−1 soil). Plants were harvested at three different times and analyzed for Cd, N, P, K, Mg, Mn, Cu, Fe and Zn concentrations. Plant biomass decreased as a result of excess Cd. Cadmium concentration in plant shoots increased with increasing Cd supply, significantly affecting the plant nutrient content. An excess Cd supply increased macronutrient and decreased micronutrient concentrations in the plant. Although, the research process will become more complicated, this new approach may help to investigate the tolerance of A. littoralis to Cd stress for use in phytoremediation. [ABSTRACT FROM AUTHOR]

Abstract: A series of investigations was conducted to evaluate the feasibility of using constructed treatment wetlands to remove pollutants from saline wastewater. Eight emergent plants; cattail, sedge, water grass, Asia crabgrass, salt meadow cordgrass, kallar grass, vetiver grass and Amazon, were planted in experimental plots and fed with municipal wastewater that was spiked with sodium chloride (NaCl) to simulate a saline concentration of approximately 14–16mScm−1. All macrophytes were found tolerant under the tested conditions except Amazon and vetiver grass. Nutrient assimilation of salt tolerant species was in the range of 0.006–0.061 and 0.0002–0.0024gm−2d−1 for nitrogen and phosphorus, respectively. Treatment performances of planted units were found to be 72.4–78.9% for BOD5, 43.2–56.0% for SS, 67.4–76.5% for NH3-N and 28.9–44.9% for TP. The most satisfactory plant growth and nitrogen assimilation were found for cattail (Typha angustifolia) though the plant growth was limited, whereas Asia crabgrass (Digitaria bicornis) was superior for BOD5 removal. Both were evaluated again in a continuous flow constructed wetland system receiving saline feed processing wastewater. A high removal rate regularly occurred in long-term operating conditions. The reduction in BOD5, SS, NH3-N and TP was in the range of 44.4–67.9%, 41.4–70.4%, 18.0–65.3% and 12.2–40.5%, respectively. Asia crabgrass often provided higher removal especially for BOD5 and SS removal. Nutrient enriched wastewater promoted flourishing growth of algae and plankton in the surface flow system, which tended to reduce treatment performance. [Copyright &y& Elsevier]

Salinity is an important abiotic stress affecting plant growth. We have known that plants can recruit beneficial microbes from the surrounding soil. However, the ecological functions of the core microbiome in salt-tolerant plants, together with their driving factors, remain largely unexplored. Here, we employed both amplicon and shotgun metagenomic sequencing to investigate the microbiome and function signatures of bulk soil and rhizocompartment samples from three salt-tolerant plants (legumes Glycine soja and Sesbania cannabina and nonlegume Sorghum bicolor). Strong filtration effects for microbes and functional genes were found in the rhizocompartments following a spatial gradient. The dominant bacteria belonged to Ensifer for legumes and Bacillus for S. bicolor . Although different salt-tolerant plants harbored distinct bacterial communities, they all enriched genes involved in cell motility, Na + transport, and plant growth-promoting function (e.g., nitrogen fixation and phosphate solubilization) in rhizoplane soils, implying that the microbiome assembly of salt-tolerant plants might depend on the ecological functions of microbes rather than microbial taxa. Moreover, three metagenome-assembled genomes affiliated to Ensifer were obtained, and their genetic basis for salt stress alleviation were predicted. Soil pH, electrical conductivity, and total nitrogen were the most important driving factors for explaining the above microbial and functional gene selection. Correspondingly, the growth of an endophyte, Ensifer meliloti CL09, was enhanced by providing root exudates, suggesting that root exudates might be one of factors in the selection of rhizosphere and endosphere microbiota. Overall, this study reveals the ecological functions of the populations inhabiting the root of salt-tolerant plants. IMPORTANCE Salinity is an important but little-studied abiotic stressor affecting plant growth. Although several previous reports have examined salt-tolerant plant microbial communities, we still lack a comprehensive understanding about the functional characteristics and genomic information of this population. The results of this study revealed the root-enriched and -depleted bacterial groups, and found three salt-tolerant plants harbored different bacterial populations. The prediction of three metagenome-assembled genomes confirmed the critical role of root dominant species in helping plants tolerate salt stress. Further analysis indicated that plants enriched microbiome from soil according to their ecological functions but not microbial taxa. This highlights the importance of microbial function in enhancing plant adaptability to saline soil and implies that we should pay more attention to microbial function and not only to taxonomic information. Ultimately, these results provide insight for future agriculture using the various functions of microorganisms on the saline soil.

Soil salinization is one of the major land degradation processes that decreases soil fertility and crop production worldwide. In this study, a long-term coastal saline soil remediation experiment was conducted with three salt-tolerant plant species: Lycium chinense Mill. (LCM), Tamarix chinensis Lour. (TCL), and Gossypium hirsutum Linn. (GHL). The three plant species successfully remediated the saline soil but showed different efficacies. The archaeal, bacterial, and fungal communities in barren soil and in four rhizocompartments (distal-rhizosphere soil, proximal-rhizosphere soil, rhizoplane, and endosphere) of the three plant species were assessed. All three plant species significantly decreased the richness of the archaeal communities but increased that of the bacterial and fungal communities in both the rhizosphere and rhizoplane compared with those in the barren soil. The archaeal and bacterial community structures were strongly influenced by the rhizocompartment, while specific fungal communities were recruited by different plant species. The microbial taxa whose abundance either increased or decreased significantly during remediation were identified. Soil electrical conductivity (EC) was identified as the main factor driving the variation in microbial community composition between the remediated and barren soil, and total nitrogen (TN), total carbon (TC), and available potassium (AK) were the main factors driving the differences among plant species. This report provides new insights into the responses of the root zone microbial communities of different salt-tolerant plant species during phytoremediation. IMPORTANCE Despite knowing that phytoremediation by salt-tolerant plants is an effective technology for ameliorating saline soils and that microorganisms contribute significantly to plant stress tolerance and soil fertility, we still lack a comprehensive understanding of how microbes respond to the growth of salt-tolerant plants and the subsequent decline in soil salinity. The results of this study revealed different response patterns among bacterial, archaeal, and fungal communities and indicated that the decline in archaeal abundance might be a sign of successful remediation of coastal saline soils. The recruitment of specific fungal communities by different plant species indicated the importance of fungi in plant species-specific remediation functions. We also identified the taxa that may play key roles during remediation, and these taxa could potentially be used as indicators of phytoremediation. Overall, these findings highlight the importance of microbes in the phytoremediation of saline soil and suggest that the mechanisms involved are plant species specific., (Copyright © 2020 Wang et al.)

This paper presents several aspects regarding the anatomy of the vegetative organs of Iris halophila Pall., a salt-tolerant plant, more or less known as a medicinal plant. [ABSTRACT FROM AUTHOR]

To reveal the correlation between plant communities and soil chemical factors (pH, the total amount of soil soluble salt, TN, TP, SOM, K + , Na + , Ca 2+ , Mg 2+ , Cl - , SO 4 2- , HCO 3 - ) in Shandong coastal saline area, a field investigation of 81 samples was carried out and the chemical properties of the soil were analyzed. The results showed that a total of 85 species, 67 genera and 30 families of salt-tolerant plants were recorded. The top three dominant families were Compositae, Gramineae and Chenopodiaceae. The community could be divided into four types: Phragmites aus-tralis - Imperata cylindrical + Artemisia capillaris, Suaeda salsa + P. australis - A. capillaris + Kochia scoparia, P. australis - Typha orientalis + Apocynum venetum, P. australis - A. venetum. The CCA sequencing results showed that the soil total soluble salt and water-soluble ions were the key chemical factors affecting the distribution of salt-tolerant vegetation, followed by total nitrogen content. The community of P. australis - I. cylindrical + A. capillaris had richest species diversity among the four community types, and the resources of salt-tolerant plants were abundant. The species diversity of plant community showed a significant negative correlation with soil total soluble salts and water soluble salt ions content. The plant community diversity index would be reduced by the high saline soil.