Taxonomy. Superdivision: Spermatophyta. Division: Angiospermae. Class: Dicotyledoneae. Family: Chenopodiaceae. Genus: Halocnemum. Halocnemum strobilaceum (hamd, jointed glasswort, Sabat) in Flora of Qatar, with photos of the plant in its habitat. Salicornia strobilacea (Synonym of Halocnemum strobilaceum) Grown under Different Tidal Regimes Selects Rhizosphere Bacteria Capable of.

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Halophytes classified under the common name of salicornia colonize salty and coastal environments across tidal inundation gradients. To unravel the role of tide-related regimes on the structure and functionality of root associated bacteria, the rhizospheric soil of Salicornia strobilacea synonym of Halocnemum strobilaceum plants was studied in a tidal zone of the coastline of Southern Tunisia.

Although total counts of cultivable bacteria did not change in the rhizosphere of plants grown along a tidal gradient, significant differences were observed in the diversity of both the cultivable and uncultivable bacterial communities.

This observation indicates that the tidal regime is contributing to the bacterial species selection in the rhizosphere. Despite the observed diversity in the bacterial community structure, the plant growth promoting PGP potential of cultivable rhizospheric bacteria, assessed through in vitro and in vivo tests, was equally distributed along the tidal gradient.

File:Halocnemum strobilaceum.jpg

Root colonization tests with selected strains proved that halophyte rhizospheric bacteria i stably colonize S. The versatility in the root colonization, the overall PGP traits and the in vivo plant growth promotion under saline condition suggest that such beneficial activities likely take place naturally under a range of tidal regimes.

Halophilic plants classified under the common name of salicornia Chenopodiaceae have been proposed jalocnemum model plants to investigate salt adaptation Feng et al. Salicornia species have great potential for phytoremediation of saline soils Al-Mailem et al. Salicornia plants are common in many saline ecosystems, comprising dry salt lakes, lagoons, and coastal areas where they are exposed to variable tidal regimes i.

Soil and sediment bacterial communities are subjected to the influence of multiple environmental parameters that shape their composition in terms of taxa and their relative abundance Fierer and Jackson, ; Fierer et al. Instead, strobilaaceum is a particular habitat where plant root exudates can gradually alters the sediment conditions to select and enrich a specific rhizo-microbiome Berg and Smalla, ; Dennis et al.

The capacity of salicornia to flourish under variable tidal conditions, including waterlogged soil, provides the unique opportunity to study tide influence on the microbiome structure. Besides contributing to the balance of carbon, nitrogen, and other elements in coastal ecosystems Kirchman et al. However, little halocnmum is available on the role of tidal flooding regimes on determining the structure and diversity of plant-associated bacterial communities ha,ocnemum their functional PGP potential.

Here, we studied the bacterial microbiome associated to Salicornia strobilacea synonym of Halocnemum strobilaceum plants grown halocnemu, different tidal regimes in a coastal area located in Southern Tunisia aiming to assess i the role of tide on the selection of rhizospheric bacterial assemblages, ii the ability of selected rhizosphere bacterial types to actively recolonize S.

Since the interaction of edaphic and host-plant factors deeply affect bacterial community structure and composition Panke-buisse et al.

The area was subjected to a constant tidal flooding Supplementary Figure 2A with an excursion ranging from 20 cm during neap tide up to 1 m during spring tide. These fluctuations generated three different tidal zones subtidal, intertidal, and supratidal; Supplementary Figures 1C—F.

Halocnemum strobilaceum – Flora of Qatar

Climate parameters are reported in the Supplementary Figure 2B. The soil salinity in the selected area was determined in the field with a handheld multi-parameter system and ranged from During the sampling campaign BioDesert III February strobilacum, salicornia plants growing in different tidal zones occurring at the studied site were identified.

According to morphology, the plants were identified as S. In laboratory the rhizosphere soil — defined as soil particles tightly adhering to roots 1—3 mm — was separated from the root system as strobjlaceum in Marasco et al. The DNA was extracted from each isolate stobilaceum boiling lysis and used to de-replicate the isolates collection using the intergenic transcribed spacers ITS -PCR fingerprinting protocol Ferjani et al.

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To resolve the distribution of the isolate the profile network was used. The network was constructed using Cytoscape version 3. The analysis take into account hhalocnemum abundance of each OTU in the samples.

Strobilaceuj was extracted from 0. The output strobiilaceum matrix was transferred to Microsoft Excel for the following analysis. Peaks showing a height value lower than 50 fluorescence units were removed from the output peak matrix before statistical analyses. The intersections between the three tidal areas have been calculated with the Veen Diagrams software 2 using as input the ARISA matrixes obtained from the three replicates. Furthermore, the isolated strains have been screened in vitro for several PGP traits, including i production of IAA and ii siderophores, iii mineral phosphate solubilization, iv EPS and for tolerance to v abiotic stresses osmotic and temperature variation following the methods described in Cherif et al.

A mini-Tn7 transposon system was used for chromosomally fluorescence-tagging halotolerant isolates by conjugation procedure Lambertsen et al. The fluorescent-labeling procedure was successful for strains SR and SR both belonging to the Pseudomonas genusas visualized by fluorescence microscopy Leica.

The two gfp -labeled strains were selected for colonization experiments on S. A gfp -labeled E. Plants were grown in non-sterile soil microcosms for 6 months starting from seeds. After this period, plantlets were gently harvest, washed, and transfer in pots containing ml of strobilacceum marine water.

Only the shoots of plants halocenmum exposed to the light to permit the normal photosynthetic activity of plants. At successive times 48 and 96 hthe roots bacterized with gfp -labeled and the control strains were gently washed to remove the non-attached bacterial cells and analyzed by confocal laser-scanning microscopes Leica TCSNT with the Leica Confocal Software.

To quantify the colonization ability of the selected strains root and shoot tissues of treated plants were randomly collected, gently washed, and smashed in physiological solution. Salicornia strobilacea scions of 4 cm were obtained and planted in commercial soil. After 1 week of adaptation, the scions were treated with the selected bacterial strains: The in vivo experiment continued for days after bacterization.

After that period the biomass parameters were measured for five replicates per treatment.

Halocnemum strobilaceum – Wikispecies

The bacterial isolates were de-replicated by strain typing through ITS fingerprinting resulting in different haplotypes. The phylogenetic affiliation of the 16S rRNA gene partial sequences and the network analysis on the dataset are reported in Figures 1A,Brespectively. Cluster analysis indicated that the supratidal rhizosphere cultivable bacterial community differed significantly from those collected in the subtidal and intertidal zones similarity The occurrence of specific bacterial assemblages in the S.

Phylogenetic affiliation of cultivable bacteria associated to the rhizosphere of Salicornia strobilacea grown under different tidal regimes.

A Bacterial isolates classification using the RDP classifier at genus level. The remaining portion of the bacteria collection had a specific composition according to the isolation from the different tidal regimes. Interestingly, no Marinobacter was isolated from the supratidal S. Most of the isolates from S. This activity was similarly spread in the three stations EPS production was detected only when bacteria grew tsrobilaceum absence of salt and it was present in a lower percentage of the isolates None of the isolates from the three types of samples presented phosphate solubilization capacities, while siderophore release was detected only in isolates from the supratidal zone in media without two strains and with three strains NaCl in the growth medium Supplementary Figure strobilaceim.

The abiotic stress tolerance was equally distributed along the tidal gradient and was not driven by the presence of NaCl in the growth medium Figures strobilaceuk. Plant growth promoting traits and abiotic stresses tolerance of S. White, gray and black bars indicate subtidal, intertidal, and supratidal samples, respectively.

A cluster analysis performed by combining the bacterial PGP and abiotic stress tolerance traits grouped the strains in four clusters Supplementary Figure 7. The phylogenetic affiliations and the functional traits of these strains were resumed in the Supplementary Table 2. After days-long experiment, plants exposed to the bacteria and their controls were harvested and analyzed.

The same strains incremented plant fresh and sgrobilaceum shoot biomass Figures 3B,C. Similarly, dry weight increment has been detected in the root system for all the tested strains except SR Figures 3D—Fconfirming that the strains promoted plant growth. The data were calculated as average of five plants per treatment and Student t -test was adopted to statistically analyze the data.


Both the Pseudomonas strains colonized the root starting from root hairs or following the surface of the connection points between principal and secondary roots, where the active growth of the tissues create favorable niche of colonization Figures 4A,B ; Supplementary Figure The microscopy strobklaceum conducted after 96 h confirmed the ability of both strains to stably colonize the root Figures 4A,B. Re-isolation of the inoculated gfp -tagged strains from plant tissue confirmed the microscope observations.

Both Pseudomonas strains were recovered at high titres from the plantlets especially from the root, indicating that they actively grow in the rhizosphere. Densities ranging from 4.

A lower number of CFU per g was observed in the shoot tissues with both the bacteria 6. Rhizocompetence and recolonization ability of S. The gfp fluorescence is visible in green. The red color represents the auto-fluorescence of root tissues when excited by the UV laser. Images were obtained with a Leica confocal microscope. D Re-isolation experiments showing the ability of Strobolaceum strains SR and SR to actively colonize both root and shoot tissues of S. In coastal habitats subjected to significant tidal ranges, the marine water flow enhances the turnover of nutrients and organisms, including the sediment microbiome.

For instance, in mangrove ecosystems, exposure to tidal flow influences the microbial growth halodnemum biomass strobiaceum intertidal surface sediments Alongi, Under the tidal flow bacteria naturally associated to plant roots are subjected to periodical changes of selective pressures, on top of those constantly imposed by the sediment and root exudates. Even though such a continuous environmental pressure variations is foreseen to influence the strobklaceum and functionality of the rhizosphere communities Haichar et al.

Our study assessed the effects of tide on strobilsceum microbiome diversity and functionality, by considering the structure of the PGP bacterial community associated to strobilacwum rhizosphere of S. We moved beyond the consideration of the sole intertidal zone: Although subjected to the rhizosphere effect and thus showing a core pool of microbial isolates, S. Such uneven distribution of bacterial isolates could be explained by the different oxygen availability in the subtidal zone, strictly related to the growth pattern of root, from which oxygen can be lost providing a more suitable surrounding environment for microbes Berg and Smalla, ; Oliveira et al.

In coastal lagoon and salt marshes, halophytes like Spartina maritimaSarcocornia perennisand Halimione portulacoidesdifferentially influence the activity and distribution of microbial populations through their diverse growth and resources allocation Oliveira et al. Similar results were obtained by Borruso et al.

Furthermore, a correlation between the bacterial communities associated to S. We are aware of the limitations of the cultivation-based approach for instance, we focused on the fast-growing bacteria that grow forming colonies after 72 h of incubation and we have not considered the slow growing bacteria.

However, we found that the distribution of the phylogenetic affiliation of bacteria isolated from S. No differences in term of total CFU per gram of strobilacem sediment were observed in the three areas.

At the phylogenetic level, FirmicutesActinobacteriaand Gammaproteobacteria were halpcnemum abundant phyla in the S. The genus Bacilluswell known for its interaction with plants Raddadi et al. Hqlocnemumfor example, was highly abundant in the subtidal and intertidal rhizospheres flooded by seawater.

Marinobacter is a halophilic genus typically found hakocnemum seawater and marine sediments McGenity et al.

Halocnemum strobilaceum

In the supratidal rhizosphere, Marinobacter and Alcanivorax were replaced by salt-loving bacteria of the genus Halomonaswhich have been previously observed in association with Salicornia spp. Together with Bacillusthe genus Pseudomonas was one of the two genera isolated using both the media and overall its abundance was higher in the supratidal rhizospheres.

Both genera are colonizing the rhizosphere of several cultivated and wild plants under stressful conditions such strobilaceeum salinity and drought Marasco et al.