Halophytic Species Research Articles

Insight into mechanisms of multiple stresses tolerance in a halophyte Aster tripolium subjected to salinity and heavy metal stress

The study aimed at comparing metabolic reactions of a halophyte Aster tripolium to abiotic stresses. Profiling of endogenous phytohormones, soluble carbohydrates and stress-related amino acids was conducted in plants exposed to moderate and high salinity (150 and 300 mM NaCl), and heavy metal salts CdCl2 or PbCl2 (100 and 200 μM).High NaCl and Pb doses inhibited growth of A. tripolium (Stress Tolerance Index STI) of 37% and 32–35%, respectively. The plants tolerated moderate salinity and Cd (STI = 91% and STI = 83–96%, respectively). Toxic metals accumulated mainly in the roots but Cd translocation to the shoots was also observed. The stressors did not affect total concentrations of the main growth promoting phytohormones but we observed enhanced deactivation of auxins and gibberellins, and reduced accumulation of jasmonate precursor. ABA content increased under stress except for moderate salinity. A common reaction was also activation of osmotic adjustment, however it was disparately manifested under salinity and metallic stress. The distinct responses to salinity and metallic stresses involved changes in carbohydrate profile and altered interplay between salicylic acid content and the pool of active gibberellins. The content of active jasmonates diversified A. tripolium reactions to salt excess and each of the heavy metals. This parameter was linked to the accumulation of ethylene precursor. The results of the study can be used to decipher potential co-tolerance mechanism of this halophyte species to multiple environmental stresses.

Accumulation potential of Atriplex halimus to zinc and lead combined with NaCl: Effects on physiological parameters and antioxidant enzymes activities

An experiment in this study was designed to investigate the effect of different concentrations of Zn2+ or Pb2+ (0, 200, 400 and 600 μM) with NaCl (0, 200 mM), on the morphological and physiological parameters as well as the antioxidative response of the halophytic species Atriplex halimus. Results showed that Pb2+ had no significant impact on biomass production while Zn2+ significantly affected plant development mainly at high concentration, 600 μM. Total chlorophyll content did not change significantly under elevation concentrations of Zn2+ when compared to control. However, there was a modest decrease in total chlorophyll concentration in the leaves of A. halimus grown in a medium supplemented with 600 μM Pb2+ and with combined stress Pb2+/NaCl. Zn2+ and Pb2+ contents in tissues were higher in the belowground organs of this halophyte. Overall results pointed out that application of different concentrations of Zn2+ or Pb2+ disturbed status of nutrients in A. halimus. Analysis of antioxidant enzymes [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] showed that the activity was diminished by increasing Zn2+ concentrations in the medium. Whereas, the addition of Pb2+ in the medium increased CAT activity and decreased APX activity.

Wild halophytic species as forage sources: Key aspects for plant breeding

AbstractThe use of wild halophytic species as forage resources in saline environments has gained increasing attention. Argentina ranks third in area of saline soils in the world, with a third of its territory showing various degrees of salinity, sodicity and/or alkalinity. On this type of soils, rangelands are the main forage resource for livestock production. Many wild species have forage potential and can also be used for the rehabilitation of rangelands and for intercropping. Information about these species, as well as on the physiological and genetic bases associated with salinity tolerance, provides relevant tools for efficient selection methods. This study addresses Argentine wild halophyte species with forage potential and describes selection criteria with an emphasis on the following taxa: (a) Poaceae: subfamily Chloridoideae and tribes Paniceae and Triticeae, (b) Fabaceae and (c) Amaranthaceae (formerly known as Chenopodiaceae). The review is intended to contribute to the general discussion on strategies for the improvement of wild plant genetic resources, using forage species naturally growing in saline soils in Argentina as a case study.

Modeling δ18O as an early indicator of regime shift arising from salinity stress in coastal vegetation

In many important coastal habitats, a combination of increasing soil salinization due to sea level rise, reduced precipitation and storm surges may induce regime shift from salinity-intolerant glycophytic vegetation to salinity-tolerant halophytic species. Early detection of regime shift due to salinity stress in vegetation may facilitate conservation efforts. It has been shown that the 18O value of water in the xylem of trees can be used as a surrogate for salinity in the rooting zone of plants. Coupling measured δ18O values in the tree xylem with simulated δ18O values in trees and salinity in the vadose zone can be used to investigate competitive responses of glycophytic versus halophytic trees. MANTRA-O18 simulations suggest that the impacts of salinization on diminishing the resilience of salinity-intolerant trees can be detected up to 25 years before the glycophytic trees are threatened with regime shift to halophytic species. This early detection provides critical lead time and valuable information and insights useful for planning adaptation strategy to mitigate against the adverse impacts of sea level rise and climate change.

Relict Anthropogenic Ecosystem from the Middle Ages: History of a Salt Marsh from Transylvania (Sic, N Romania)

ABSTRACTA paleoecological study was performed on a sediment core recovered from a former artificial lake – the Reedbed of Sic near Cluj-Napoca, Romania – in order to explore the history of water management and nearby salt mining, and its impact on the environment. From the Roman period, the area served as a recipient of salty wastewaters. The most significant shift in the sediment composition and macrofossil assemblages took place after 1000 AD, suggesting a significant upturn in salt mining. The impact of mining-related activities was further increased in the Middle Ages when, according to documentary sources, fishponds and watermills were constructed in the area. They led to the stabilisation of the water level in the lakebed, and enhanced the appearance of reed beds and the spread of secondary salt marsh vegetation. This biotop was later invaded by the Entzia macrescens, an agglutinated foraminiferal taxon, known mostly from the high intertidal marshes worldwide. In the investigated marshland, the dominance of halophytic species reached their acme in the seventeenth century, which coincides with the acme of mining activities. This medieval – early Modern Age industrial ecosystem survived the abandonment of salt mines and fishponds, being preserved until today.

Effect of NaCl on the photosynthetic pathways of halophytic leaf succulent Sedum uniflorum

The effect of NaCl on the photosynthetic pathways of the only halophytic subtropical species Sedum uniflorum was examined in the field in northern Taiwan and in the laboratory. Plants growing in the field exhibited CAM-cycling regardless of salt content in their tissues. In contrast, NaCl treatment in the laboratory induced CAM photosynthesis, while control plants exhibited a C3-CAM intermediacy. This high level of photosynthetic pathway variablility matches that of other Sedum species.

Clustering of halophytic species from Cyprus based on ionic contents

This paper presents the work conducted on the chemical constituents of some common and widely distributed halophyte taxa from Cyprus with the aim that these studies will help in the evaluation of halophytes for different economical purposes. The plant species of Crithmum maritimum L., Limbarda crithmoides (L.) Dumort, Atriplex portulacoides L., Salsola kali L., Atriplex halimus L., Limonium oleifolium Mill., L. meyeri (Boiss.) Kuntze; and Tetraena alba (L.f.) Beier & Thulin were collected in the middle of July. The shoot tissue and leaf samples were collected from the natural habitats and left for drying under air circulation followed by placing them in oven at 60 °C for 96 hours. The material was crushed using mortar and pestle and subjected to an analysis of macro- and micro-nutrients and biochemical compounds. K+/Na+ in the leaf tissues of the dicot species showed relatively high values depicting their behavior as Na+ includes but very low Cl- levels were recorded. Out of the species investigated here in 4 TFAA content was rather high. Values ranging from 0.5% to 1% dry weight were exhibited in one species. However, only 3 species showed very low TFAA values. Later may be due to low nitrogen availability in their environment. The phenetic analyses of eight halophyte species performed on the data matrix using Ntsys-pc program version 2.1 revealed that, cluster analysis of the overall results obtained here leads to 2 clusters. This discrimination appears to be as a result of their different abilities to accumulate either proline or glycine betaine.

Potential for Heightened Sulfur-Metabolic Capacity in Coastal Subtropical Microalgae

SummaryThe activities of microalgae support nutrient cycling that helps to sustain aquatic and terrestrial ecosystems. Most microalgal species, especially those from the subtropics, are genomically uncharacterized. Here we report the isolation and genomic characterization of 22 microalgal species from subtropical coastal regions belonging to multiple clades and three from temperate areas. Halotolerant strains including Halamphora, Dunaliella, Nannochloris, and Chloroidium comprised the majority of these isolates. The subtropical-based microalgae contained arrays of methyltransferase, pyridine nucleotide-disulfide oxidoreductase, abhydrolase, cystathionine synthase, and small-molecule transporter domains present at high relative abundance. We found that genes for sulfate transport, sulfotransferase, and glutathione S-transferase activities were especially abundant in subtropical, coastal microalgal species and halophytic species in general. Our metabolomics analyses indicate lineage- and habitat-specific sets of biomolecules implicated in niche-specific biological processes. This work effectively expands the collection of available microalgal genomes by ∼50%, and the generated resources provide perspectives for studying halophyte adaptive traits.

Impacts of bracteole removal and seeding rate on seedling emergence of halophyte shrubs: implications for rangeland rehabilitation in arid environments

Direct seeding techniques often result in unsatisfactory outcomes in rangeland rehabilitation, primarily because of low seedling emergence and poor establishment. Seed processing techniques aimed at improving seedling emergence have gained interest by pasture managers. The purpose of this study was to investigate the combined effects of bracteole removal and seeding rate on seedling emergence in seven halophytic species: Atriplex halimus, A. canescens, A. leucoclada, A. nummularia, A. lentiformis, Salsola vermiculata and Haloxylon aphyllum under semi-arid conditions in Tel Hadya (Syria). Each of these species was evaluated for seedling emergence under two seed treatments (bracteoles removed and non-removed bracteoles) with three seeding rates (10, 30 and 60 seeds per pot), in a completely randomised block design. The results showed a positive effect of seed treatment on seedling emergence for all studied species. The native A. halimus had the highest emergence percentages whereas the introduced A. mummularia, had the lowest. However, there were no significant effects of seeding rates on seedling emergence. These results showed that bracteole removal could improve germination and seedling emergence, and potentially increase the rate of establishment of the species studied. Therefore, when implementing rangeland rehabilitation projects, bracteole removal needs to be considered. The native S. vermiculata should be recommended for direct seeding in the West Asia and North Africa region given its high seedling emergence, known high palatability, nutritive value, and high auto-regeneration performance.

New floristic records from Central Europe 3 (reports 13–40)

The third part of the series includes 28 new chorological records of vascular plants from Austria, Czechia, Slovakia, Transcarpathian Ukraine and Romania. From Austria, new record of Hyoscyamus niger was reported. In Czechia in the Bílé Karpaty Mts., new sites of Corydalis lutea, Ranunculus arvensis and Thlaspi perfoliatum were recorded. In eastern Slovakia, two neophyte species Robinia viscosa and Pyrethrum parthenium were found and the new altitudinal maximum for halophyte species Taraxacum bessarabicum in 418 m above sea level was recorded. In the Ukrainian Carpathians, new sites of Lycopodium alpinum and Phyteuma vagneri in the massif of the Polonina Krasna were found as well as new records of Aronia melanocarpa and Inula helenium in the valley of the Latorica river. From the Romanian Carpathians, Festuca stricta subsp. saxatilis, Pulmonaria filarszkyana, Saxifraga luteoviridis and Silene zawadzkii in the Maramureş Mts. were recorded as well as rare orchid Ophrys insectifera from Retezat Mts.

Germination Response to Osmotic Potential, Osmotic Agents, and Temperature of Five Halophytes Occurring along a Salinity Gradient

Premise of research. Halophyte species grow where salt concentrations are high. Still, their germination may be affected by salts, either by creating an osmotic potential that prevents water uptake...

The Use of Native Halophytes in Landscape Design in The Central Anatolia, Turkey

In this study, the usability of some herbaceous halophytes grown naturally in salt marshes that dry most of the year in Central Anatolia Region were investigated in landscape design. Within the scope of the research, in the years of 2016 and 2017, seasonal field studies were carried out in saline habitats in the vicinity of Konya, Ankara, Aksaray and Nevşehir, and taken photographs and herbarium samples of halophytic plant species. The general botanical and ecological characteristics of the selected species are given and the values used in landscape design have been determined considering the aesthetic and functional properties. As a result of the field studies carried out during the vegetation periods, 59 halophytic plant species, belonging to 38 genera and 19 families that could be used in landscape design were identified. The most representative family was the Asteraceae with 11 species, followed by Plumbaginaceae (9 species) and Chenopodiaceae (8 species). The genus Limonium from Plumbaginaceae family is well represented with 8 species for landscape use. The endemism rate of halophytes used in landscape design is 42% (25 species) in the research area. The most common uses in landscape design are determined in roof gardens by 49 species, followed in ground conservation and erosion prevention by 31 species. Since these halophytic species, which are mostly succulent and endemic, are well adapted into both wet and dry areas. Their use in landscape design is of great importance for restoration of arid and barren land, which may increase as a result of global climate change, conservation of biodiversity as well as sustainable agricultural practices.

Diversidad de halófitas chilenas: distribución, origen y hábito

Halophyte species are recognized for their ability to survive in salty environments. However, this condition greatly variesamong plant taxons, difficulting their proper classification. Currently, the eHALOPH database registers halophyte speciesfrom around the world, under a single salinity criterion. In the present study, the first list of halophyte species present inChile made from eHALOPH is presented. Results indicate a diversity of 138 species, distributed in 31 families. Over 80%of species are herbaceous and nearly 55% are exotic. The largest richness was found in Coquimbo and Valparaiso regions,and the lowest in the insular territory. These results are a first approximation to halophyte diversity in Chile. At the sametime, it poses a challenge to advance in their recognition in order to propose strategies for their conservation and use.

Free phenolic compounds extraction from Brazilian halophytes, soybean and rice bran by ultrasound-assisted and orbital shaker methods.

In several countries halophytes are commercially cultivated in low saline or even irrigated with seawater, as well as with saline aquaculture effluent, like a sea asparagus Sarcocornia ambigua, that show a biotechnological potential for bioactive compounds production. However, their recovery from matrix is sometimes inefficient because the lignocellulosic materials difficult the solvent action when drastic conditions are not applied. The ultrasound-assisted extraction (UAE) was optimized by a central composite rotational design for recovery free phenolic compounds (FPC) from the sea asparagus S. ambigua. Optimum conditions were validated and compared with orbital shaker extraction for S. ambigua, other Brazilian halophytes (Apium graveolens, Myrsine parvifolia, Paspalum vaginatum, and Schinus terebinthifolius), soybean and rice bran. Except for P. vaginatum, soybean and rice bran, UAE yielded 18-29% higher FPC than that of the orbital shaker. Besides this analytical performance UAE method optimized is faster than the orbital shaker, providing shorter exposure of the analyst to the extractor solvent and applicable in matrices with different compositions. It was also demonstrated that halophytes species showed to be good natural sources of FPC in a better way as soybean and rice bran. This work was the first to report FPC in M. parvifolia and P. vaginatum.

Bacterial Diversity Associated With the Rhizosphere and Endosphere of Two Halophytes: Glaux maritima and Salicornia europaea.

Root-associated microbial communities are very important in the adaptation of halophytes to coastal environments. However, little has been reported on microbial community structures related to halophytes, or on comparisons of their compositions among halophytic plant species. Here, we studied the diversity and community structure of both rhizosphere and root endosphere bacteria in two halophytic plants: Glaux maritima and Salicornia europaea. We sampled the rhizosphere, the root endosphere, and bulk control soil samples, and performed bacterial 16S rRNA sequencing using the Illumina MiSeq platform to characterize the bacterial community diversities in the rhizosphere and root endosphere of both halophytes. Among the G. maritima samples, the richness and diversity of bacteria in the rhizosphere were higher than those in the root endosphere but were lower than those of the bulk soil. In contrast for S. europaea, the bulk soil, the rhizosphere, and the root endosphere all had similar bacterial richness and diversity. The number of unique operational taxonomic units within the root endosphere, the rhizosphere, and the bulk soil were 181, 366, and 924 in G. maritima and 126, 416, and 596 in S. europaea, respectively, implying habitat-specific patterns for each halophyte. In total, 35 phyla and 566 genera were identified. The dominant phyla across all samples were Proteobacteria and Bacteroidetes. Actinobacteria was extremely abundant in the root endosphere from G. maritima. Beneficial bacterial genera were enriched in the root endosphere and rhizosphere in both halophytes. Rhizobium, Actinoplanes, and Marinomonas were highly abundant in G. maritima, whereas Sulfurimonas and Coleofasciculus were highly abundant in S. europaea. A principal coordinate analysis demonstrated significant differences in the microbiota composition associated with the plant species and type of sample. These results strongly indicate that there are clear differences in bacterial community structure and diversity between G. maritima and S. europaea. This is the first report to characterize the root microbiome of G. maritima, and to compare the diversity and community structure of rhizosphere and root endosphere bacteria between G. maritima and S. europaea.

Plant Tissues and Embryos Biominerals in Sarcocornia pruinosa, a Halophyte from the Río Tinto Salt Marshes

Although biomineralization in plants is an important area of research, there is very limited information. In this work, we report the location of Na, K, Ca, Mg and Fe biominerals in Sarcocornia pruinosa (Chenopodiacaeae), a halophyte species growing in the estuarine area of Río Tinto, an extreme acidic environment. The estuarine soils of the Tinto basin are characterized by slightly acidic pH and high concentrations of ions. They are exposed to Atlantic Ocean tides that contribute to the increase in pH, Na and Mg concentrations. The aim of this work was to characterize the elemental composition and to identify the biominerals detected in cell tissues of S. pruinosa. Analytical techniques, such as ICP-MS (Inductively coupled plasma mass spectrometry), XRD and microscopy such as OM (optical microscopy) with histochemical staining, SEM and TEM (scanning and transmission electronic microscopy) coupled with EDX (energy dispersive X-ray) were carried out to analyze the plant tissues of S. pruinosa and characterize the detected biominerals. The elemental composition in succulent stems and seeds of S. pruinosa showed high values of Na and K followed by Ca, Mg and Fe. The presence of halite, sylvite, weddellite, glushinskite and Fe oxides biominerals in this halophyte species is reported. Our data suggest the importance of vegetation in the biogeochemical cycles in estuarine areas.

Microbacterium halophytorum sp. nov., a novel endophytic actinobacterium isolated from halophytes.

Two actinobacterial strains, YJYP 303T and YZYP 518, were isolated from two species of halophytes collected from the southern edge of the Gurbantunggut Desert. Cells were Gram-stain-positive, aerobic, short rods and without flagella. Growth of the two strains was found to occur at 4-44 °C, pH 6.0-12.0 and in the presence of up to 15 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two strains are associated with members of the genus Microbacterium. In the phylogenetic tree, the two strains shared a clade with Microbacterium halotolerans YIM 70130T (97.58 % 16S rRNA gene sequence identity) and Microbacterium populi KCTC 29152T (96.54 %). The average nucleotide identity values of strain YJYP 303T and YZYP 518 to M. halotolerans YIM 70130T were determined to be 79.97 and 80.03 %, respectively. The genomic DNA G+C contents of strains YJYP 303T and YZYP 518 were 69.72 and 70.57 %, respectively. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The predominant respiratory quinones was MK-11, followed by MK-10 and MK-12. The muramic acid type of peptidoglycan was N-glycolyl. The whole-cell sugars were mannose, ribose, rhamnose, glucose, galactose and two unidentified sugars. The cell-wall amino acids were glutamic acid, ornithine, glycine and alanine. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unidentified glycolipid. On the basis of the evidence presented in this study, strains YJYP 303T and YZYP 518 are characterized as members of a novel species in the genus Microbacterium, for which the name Microbacteriumhalophytorum sp. nov. is proposed. The type strain is YJYP 303T (=CGMCC 1.16264T=KCTC 49100T).

Combined effects of NaCl and Cd2+ stress on the photosynthetic apparatus of Thellungiella salsuginea

Plants show complex responses to abiotic stress while, the effect of the stress combinations can be different to those seen when each stress is applied individually. Here, we report on the effects of salt and/or cadmium on photosynthetic apparatus of Thellungiella salsuginea. Our results showed a considerable reduction of plant growth with some symptoms of toxicity, especially with cadmium treatment. The structural integrity of both photosystems (PSI and PSII) was mostly maintained under salt stress. Cadmium induced a considerable decrease of both PSI and PSII quantum yields and the electron transport rate ETR(I) and ETR(II) paralleled by an increase of non-photochemical quenching (NPQ). In addition, cadmium alone affects the rate of primary photochemistry by an increase of fluorescence at O-J phase and also the photo-electrochemical quenching at J-I phase. A positive L-band appeared with (Cd) treatment as an indicator of lower PSII connectivity, and a positive K-band reflecting the imbalance in number of electrons at donor and acceptor side. In continuity to our previous studies which showed that NaCl supply reduced Cd2+ uptake and limited its accumulation in shoot of divers halophyte species, here as a consequence, we demonstrated the NaCl-induced enhancement effect of Cd2+ toxicity on the PSII activity by maintaining the photosynthetic electron transport chain as evidenced by the differences in ψO, φEo, ABS/RC and TR0/RC and by improvement of performance index PI(ABS), especially after short time of treatment. A significant decrease of LHCII, D1 and CP47 amounts was detected under (Cd) treatment. However, NaCl supply alleviates the Cd2+ effect on protein abundance including LHCII and PSII core complex (D1 and CP47).

Multivariate statistical analyses for studying kenaf germination, growth, and fiber production under salinity constraint

It is due to the lack of renewable fiber sources for industrial purposes that the need for finding available and alternative material has become imperative. Kenaf (Hibiscus cannabinus L.), a fast-growing industrial crop, would be a potential solution for valorizing salinized lands and/or soils irrigated with saline water. With the aim of selecting and valorizing salt-tolerant species with high fiber yields and industrial values, we launched the assessment of the performance of kenaf culture (var. Guangdong 743-2) under salinity constraints. Germination and vegetative stages were considered in the present study to better evaluate the whole life cycle of the species. Several NaCl concentrations (0, 3, 6, 9, 12, and 15 g L-1) were applied to seeds cultivated in petri dishes and to 4-month-old plants growing in hydroponics. Germination rates (germination capacity and coefficient of velocity), growth characteristics (biomass production and relative growth rate), physiological parameters (ionic content and water status), and fiber yields (neutral detergent fiber, acid detergent fiber, and acid detergent lignin) were evaluated to better understand the salt stress and toxic effects on germination, growth, and fiber yield. Multivariate analyses were used to identify the major characteristics pertaining to salinity tolerance. The obtained results have shown that kenaf variety Guangdong 743-2 is able to germinate and grow under high salinity levels (up to 15 g L-1 NaCl), deploying several mechanisms of adaptation. Kenaf could withstand salt stress by germinating smoothly, preserving root and stem biomass, maintaining relative growth rate, stabilizing root water content, producing new leaves while sacrificing older ones, and behaving as a halophyte species through the inclusion of toxic ions within the aerial part, most probably compartmentalized inside vacuoles to ultimately keep its fiber yields unchanged.

Draft genome sequence of first monocot-halophytic species Oryza coarctata reveals stress-specific genes

Oryza coarctata (KKLL; 2n = 4x = 48, 665 Mb) also known as Porteresia coarctata is an extreme halophyte species of genus Oryza. Using Illumina and Nanopore reads, we achieved the assembled genome size of 569.9 Mb, accounting 85.69% of the estimated genome size with N50 of 1.85 Mb and 19.89% repetitive region. We also found 230,968 simple sequence repeats (SSRs) and 5,512 non-coding RNAs (ncRNAs). The functional annotation of predicted 33,627 protein-coding genes and 4,916 transcription factors revealed that high salinity adaptation of this species is due to the exclusive or excessive presence of stress-specific genes as compared to rice. We have identified 8 homologs to salt-tolerant SOS1 genes, one of the three main components of salt overly sensitive (SOS) signal pathway. On the other hand, the phylogenetic analysis of the assembled chloroplast (134.75 kb) and mitochondrial genome (491.06 kb) favours the conservative nature of these organelle genomes within Oryza taxon.