Plant Growth Promoting Microorganisms Useful for Soil Desalinization

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Applied Biosciences and Bioengineering".

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 39851

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Department of Chemistry and Biology “A. Zambelli”, University of Salerno, 84084 Fisciano, Italy
Interests: phytoremediation; bioremediation; plant-growth-promoting bacteria (PGPB); molecular population genetics
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Guest Editor
Department of Chemistry and Biology “A. Zambelli”, University of Salerno, 84084 Fisciano, Italy
Interests: biomonitoring; phytoremediation; biodiversity; environmental pollution
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Chemistry and Biology “A. Zambelli”, University of Salerno, Via G. Paolo II n° 132, 84084 Fisciano, Italy
Interests: plant roots; plant–soil interaction; environmental and applied botany; plant biotechnology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Salinization of cultivable soils is one major issue that humankind will have soon to face. It has been estimated that around 20% of lands all around the world are cultivable, and over 30% of them, at present, are affected by salinization. Moreover, it has been calculated by economists and agronomists that each year, about 10% of arable soils increases its own salt content due, for instance, to irrigation with salted water and use of incorrect agricultural practices, such as abundant employ of mineral fertilizers. Consequently, it is conceivable that in next thirty years, more than 50% of them will be severely affected by a high salt content, causing a reduction of crop yields and also their palatability. Moreover, temperature increase, due to climate change, will worsen the problem even more. In this perspective, during the last decade, researchers have focused their studies on the microbiome of several organisms as well as that of plants. In fact, it has been recognized that a relevant role to maintain and improve plant health is played by microorganisms of the rhizosphere, a thin layer of soil of 1–2 mm surrounding the fine roots of the plants. The new-generation sequence (NGS) technique, able to sequence up to the whole genome of every kind of living being, has revealed an unknown world of microorganisms that inhabit the rhizosphere, and many of them carry even out the function of plant growth promoters (PGP microorganisms), reducing either biotic or abiotic stress such as that caused, for instance, by soil salinization. The tolerance to high salt concentrations of certain microorganism strains and their capability to improve the plant wellness have been demonstrated by some studies. The combination of these salt-tolerant PGP microorganisms with halo-tolerant crops (e.g., quinoa) could provide an income to farmers of these areas of the world which are usually very poor, but also a mitigation of this serious problem throughout a phytoremediation process.

For the above-mentioned reasons, we are proposing the collection of scientific manuscripts which can shed light on principles which regulate interactions among plants and microorganisms in the case of salty and arid cultivable soils.

Prof. Dr. Stefano Castiglione
Dr. Francesco Guarino
Dr. Mattia Terzaghi
Guest Editors

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Keywords

  • soil salinization
  • bio-phytoremediation
  • constructed wetlands
  • halophyte plants
  • PGPB
  • salt-tolerant microorganisms
  • microbiome

Published Papers (8 papers)

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Editorial

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3 pages, 173 KiB  
Editorial
Plant Growth Promoting Microorganisms Useful for Soil Desalinization
by Mattia Terzaghi, Stefano Castiglione and Francesco Guarino
Appl. Sci. 2022, 12(5), 2578; https://0-doi-org.brum.beds.ac.uk/10.3390/app12052578 - 02 Mar 2022
Cited by 2 | Viewed by 1311
Abstract
The salinization of cultivable soils is a major issue that humankind will soon have to face [...] Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)

Research

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28 pages, 4510 KiB  
Article
The Root Microbiome of Salicornia ramosissima as a Seedbank for Plant-Growth Promoting Halotolerant Bacteria
by Maria J. Ferreira, Angela Cunha, Sandro Figueiredo, Pedro Faustino, Carla Patinha, Helena Silva and Isabel N. Sierra-Garcia
Appl. Sci. 2021, 11(5), 2233; https://0-doi-org.brum.beds.ac.uk/10.3390/app11052233 - 03 Mar 2021
Cited by 17 | Viewed by 3508
Abstract
Root−associated microbial communities play important roles in the process of adaptation of plant hosts to environment stressors, and in this perspective, the microbiome of halophytes represents a valuable model for understanding the contribution of microorganisms to plant tolerance to salt. Although considered as [...] Read more.
Root−associated microbial communities play important roles in the process of adaptation of plant hosts to environment stressors, and in this perspective, the microbiome of halophytes represents a valuable model for understanding the contribution of microorganisms to plant tolerance to salt. Although considered as the most promising halophyte candidate to crop cultivation, Salicornia ramosissima is one of the least-studied species in terms of microbiome composition and the effect of sediment properties on the diversity of plant-growth promoting bacteria associated with the roots. In this work, we aimed at isolating and characterizing halotolerant bacteria associated with the rhizosphere and root tissues of S. ramosissima, envisaging their application in saline agriculture. Endophytic and rhizosphere bacteria were isolated from wild and crop cultivated plants, growing in different estuarine conditions. Isolates were identified based on 16S rRNA sequences and screened for plant-growth promotion traits. The subsets of isolates from different sampling sites were very different in terms of composition but consistent in terms of the plant-growth promoting traits represented. Bacillus was the most represented genus and expressed the wider range of extracellular enzymatic activities. Halotolerant strains of Salinicola, Pseudomonas, Oceanobacillus, Halomonas, Providencia, Bacillus, Psychrobacter and Brevibacterium also exhibited several plant-growth promotion traits (e.g., 3-indole acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophores, phosphate solubilization). Considering the taxonomic diversity and the plant-growth promotion potential of the isolates, the collection represents a valuable resource that can be used to optimize the crop cultivation of Salicornia under different environmental conditions and for the attenuation of salt stress in non-halophytes, considering the global threat of arable soil salinization. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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15 pages, 1004 KiB  
Article
Effects of Compost Amendment on Glycophyte and Halophyte Crops Grown on Saline Soils: Isolation and Characterization of Rhizobacteria with Plant Growth Promoting Features and High Salt Resistance
by Stefano Castiglione, Gianmaria Oliva, Giovanni Vigliotta, Giorgia Novello, Elisa Gamalero, Guido Lingua, Angela Cicatelli and Francesco Guarino
Appl. Sci. 2021, 11(5), 2125; https://0-doi-org.brum.beds.ac.uk/10.3390/app11052125 - 27 Feb 2021
Cited by 16 | Viewed by 3518
Abstract
Soil salinization and desertification due to climate change are the most relevant challenges for the agriculture of the 21st century. Soil compost amendment and plant growth promoting rhizobacteria (PGP-R) are valuable tools to mitigate salinization and desertification impacts on agricultural soils. Selection of [...] Read more.
Soil salinization and desertification due to climate change are the most relevant challenges for the agriculture of the 21st century. Soil compost amendment and plant growth promoting rhizobacteria (PGP-R) are valuable tools to mitigate salinization and desertification impacts on agricultural soils. Selection of novel halo/thermo-tolerant bacteria from the rhizosphere of glicophytes and halophytes, grown on soil compost amended and watered with 150/300 mM NaCl, was the main objective of our study. Beneficial effects on the biomass, well-being and resilience, exerted on the assayed crops (maize, tomato, sunflower and quinoa), were clearly observable when soils were amended with 20% compost despite the very high soil electric conductivity (EC). Soil compost amendment not only was able to increase crop growth and biomass, but also their resilience to the stress caused by very high soil EC (up to 20 dS m−1). Moreover, compost amendment has proved itself a valuable source of highly halo-(4.0 M NaCl)/thermo tolerant rhizobacteria (55 °C), showing typical PGP features. Among the 13 rhizobacterial isolates, molecularly and biochemically characterized, two bacterial strains showed several biochemical PGP features. The use of compost is growing all around the world reducing considerably for farmers soil fertilization costs. In fact, only in Italy its utilization has ensured, in the last years, a saving of 650 million euro for the farmers, without taking into account the environment and human health benefits. Furthermore, the isolation of halo/thermo-tolerant PGPR strains and their use will allow the recovery and cultivation of hundreds of thousands of hectares of saline and arid soils now unproductive, making agriculture more respectful of agro-ecosystems also in view of upcoming climate change. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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26 pages, 5623 KiB  
Article
Mitigation of NaCl Stress in Wheat by Rhizosphere Engineering Using Salt Habitat Adapted PGPR Halotolerant Bacteria
by Souhila Kerbab, Allaoua Silini, Ali Chenari Bouket, Hafsa Cherif-Silini, Manal Eshelli, Nour El Houda Rabhi and Lassaad Belbahri
Appl. Sci. 2021, 11(3), 1034; https://0-doi-org.brum.beds.ac.uk/10.3390/app11031034 - 24 Jan 2021
Cited by 52 | Viewed by 5317
Abstract
There is a great interest in mitigating soil salinity that limits plant growth and productivity. In this study, eighty-nine strains were isolated from the rhizosphere and endosphere of two halophyte species (Suaeda mollis and Salsola tetrandra) collected from three chotts in [...] Read more.
There is a great interest in mitigating soil salinity that limits plant growth and productivity. In this study, eighty-nine strains were isolated from the rhizosphere and endosphere of two halophyte species (Suaeda mollis and Salsola tetrandra) collected from three chotts in Algeria. They were screened for diverse plant growth-promoting traits, antifungal activity and tolerance to different physico-chemical conditions (pH, PEG, and NaCl) to evaluate their efficiency in mitigating salt stress and enhancing the growth of Arabidopsis thaliana and durum wheat under NaCl–stress conditions. Three bacterial strains BR5, OR15, and RB13 were finally selected and identified as Bacillus atropheus. The Bacterial strains (separately and combined) were then used for inoculating Arabidopsis thaliana and durum wheat during the seed germination stage under NaCl stress conditions. Results indicated that inoculation of both plant spp. with the bacterial strains separately or combined considerably improved the growth parameters. Three soils with different salinity levels (S1 = 0.48, S2 = 3.81, and S3 = 2.80 mS/cm) were used to investigate the effects of selected strains (BR5, OR15, and RB13; separately and combined) on several growth parameters of wheat plants. The inoculation (notably the multi-strain consortium) proved a better approach to increase the chlorophyll and carotenoid contents as compared to control plants. However, proline content, lipid peroxidation, and activities of antioxidant enzymes decreased after inoculation with the plant growth-promoting rhizobacteria (PGPR) that can attenuate the adverse effects of salt stress by reducing the reactive oxygen species (ROS) production. These results indicated that under saline soil conditions, halotolerant PGPR strains are promising candidates as biofertilizers under salt stress conditions. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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21 pages, 2508 KiB  
Article
Screening of Bacterial Endophytes Able to Promote Plant Growth and Increase Salinity Tolerance
by Elisa Gamalero, Nicoletta Favale, Elisa Bona, Giorgia Novello, Patrizia Cesaro, Nadia Massa, Bernard R. Glick, Ma del Carmen Orozco-Mosqueda, Graziella Berta and Guido Lingua
Appl. Sci. 2020, 10(17), 5767; https://0-doi-org.brum.beds.ac.uk/10.3390/app10175767 - 20 Aug 2020
Cited by 20 | Viewed by 4236
Abstract
Bacterial endophytes can colonize plant tissues without harming the plant. Instead, they are often able to increase plant growth and tolerance to environmental stresses. In this work, new strains of bacterial endophytes were isolated from three economically important crop plants (sorghum, cucumber and [...] Read more.
Bacterial endophytes can colonize plant tissues without harming the plant. Instead, they are often able to increase plant growth and tolerance to environmental stresses. In this work, new strains of bacterial endophytes were isolated from three economically important crop plants (sorghum, cucumber and tomato) grown in three different regions in soils with different management. All bacterial strains were identified by 16S rRNA sequencing and characterized for plant beneficial traits. Based on physiological activities, we selected eight strains that were further tested for their antibiotic resistance profile and for the ability to efficiently colonize the interior of sorghum plants. According to the results of the re-inoculation test, five strains were used to inoculate sorghum seeds. Then, plant growth promotion activity was assessed on sorghum plants exposed to salinity stress. Only two bacterial endophytes increased plant biomass, but three of them delayed or reduced plant salinity stress symptoms. These five strains were then characterized for the ability to produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which is involved in the increase of stress tolerance. Pseudomonas brassicacearum SVB6R1 was the only strain that was able to produce this enzyme, suggesting that ACC deaminase is not the only physiological trait involved in conferring plant tolerance to salt stress in these bacterial strains. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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14 pages, 582 KiB  
Article
Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses
by Mohammad Yaghoubi Khanghahi, Sabrina Strafella and Carmine Crecchio
Appl. Sci. 2020, 10(15), 5031; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155031 - 22 Jul 2020
Cited by 13 | Viewed by 2144
Abstract
The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out [...] Read more.
The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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Review

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20 pages, 489 KiB  
Review
Plant-Growth-Promoting Bacteria Mitigating Soil Salinity Stress in Plants
by Stefan Shilev
Appl. Sci. 2020, 10(20), 7326; https://0-doi-org.brum.beds.ac.uk/10.3390/app10207326 - 19 Oct 2020
Cited by 71 | Viewed by 6814
Abstract
Soil deterioration has led to problems with the nutrition of the world’s population. As one of the most serious stressors, soil salinization has a negative effect on the quantity and quality of agricultural production, drawing attention to the need for environmentally friendly technologies [...] Read more.
Soil deterioration has led to problems with the nutrition of the world’s population. As one of the most serious stressors, soil salinization has a negative effect on the quantity and quality of agricultural production, drawing attention to the need for environmentally friendly technologies to overcome the adverse effects. The use of plant-growth-promoting bacteria (PGPB) can be a key factor in reducing salinity stress in plants as they are already introduced in practice. Plants having halotolerant PGPB in their root surroundings improve in diverse morphological, physiological, and biochemical aspects due to their multiple plant-growth-promoting traits. These beneficial effects are related to the excretion of bacterial phytohormones and modulation of their expression, improvement of the availability of soil nutrients, and the release of organic compounds that modify plant rhizosphere and function as signaling molecules, thus contributing to the plant’s salinity tolerance. This review aims to elucidate mechanisms by which PGPB are able to increase plant tolerance under soil salinity. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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27 pages, 920 KiB  
Review
Current Advances in Plant Growth Promoting Bacteria Alleviating Salt Stress for Sustainable Agriculture
by Slimane Mokrani, El-hafid Nabti and Cristina Cruz
Appl. Sci. 2020, 10(20), 7025; https://0-doi-org.brum.beds.ac.uk/10.3390/app10207025 - 10 Oct 2020
Cited by 51 | Viewed by 12069
Abstract
Humanity in the modern world is confronted with diverse problems at several levels. The environmental concern is probably the most important as it threatens different ecosystems, food, and farming as well as humans, animals, and plants. More specifically, salinization of agricultural soils is [...] Read more.
Humanity in the modern world is confronted with diverse problems at several levels. The environmental concern is probably the most important as it threatens different ecosystems, food, and farming as well as humans, animals, and plants. More specifically, salinization of agricultural soils is a global concern because of on one side, the permanent increase of the areas affected, and on the other side, the disastrous damage caused to various plants affecting hugely crop productivity and yields. Currently, great attention is directed towards the use of Plant Growth Promoting Bacteria (PGPB). This alternative method, which is healthy, safe, and ecological, seems to be very promising in terms of simultaneous salinity alleviation and improving crop productivity. This review attempts to deal with different aspects of the current advances concerning the use of PGPBs for saline stress alleviation. The objective is to explain, discuss, and present the current progress in this area of research. We firstly discuss the implication of PGPB on soil desalinization. We present the impacts of salinity on crops. We look for the different salinity origin and its impacts on plants. We discuss the impacts of salinity on soil. Then, we review various recent progress of hemophilic PGPB for sustainable agriculture. We categorize the mechanisms of PGPB toward salinity tolerance. We discuss the use of PGPB inoculants under salinity that can reduce chemical fertilization. Finally, we present some possible directions for future investigation. It seems that PGPBs use for saline stress alleviation gain more importance, investigations, and applications. Regarding the complexity of the mechanisms implicated in this domain, various aspects remain to be elucidated. Full article
(This article belongs to the Special Issue Plant Growth Promoting Microorganisms Useful for Soil Desalinization)
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