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Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi

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A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Protection and Biotic Interactions".

Deadline for manuscript submissions: 31 July 2024 | Viewed by 10191

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Special Issue Editors

Dr. Loretta Pace

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Guest Editor

Department of Life, Health and Environmental Sciences, University of L’Aquila, Via Vetoio, 67100 Coppito, Italy
Interests: environmental and applied botany; plant-microbe interactions; plant growth-promoting bacteria; ex situ conservation; plant in vitro and in vivo propagation; sustainable agriculture

Dr. Rihab Djebaili

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Guest Editor

Department of Life, Health and Environmental Sciences, University of L’Aquila, Via Vetoio, Coppito, 67100 L’Aquila, Italy
Interests: microbiology; microbial inoculants; plant growth-promoting bacteria; arbuscular mycorrhizal fungi; plant–microbe interactions; biofertilization; sustainable agriculture; actinobacteria; cyanobacteria; the extraction of metabolites from microbes for agriculture application

Special Issue Information

Dear Colleagues,

Understanding soil–plant–microbe interactions is crucial for maintaining proper soil-mediated ecosystem services necessary for living beings. Excessive and unsustainable agricultural methods can reduce soil microbial diversity, which has an impact on plant growth. Therefore, searching for strategies to resolve agriculture problems linked to mismanagement and climate change is necessary. Plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) are widely spread soil-borne microorganisms that interact symbiotically with a variety of terrestrial plants. These organisms may speed up plant growth and soil health through both direct and indirect mechanisms, such as nitrogen fixation, nutrient solubilization, the control of plant hormonal balance, and the induction of systemic resistance in plants. These microbes can either be inoculated separately or in combination, in order to provide maximum benefits to plants and take advantage of microbial biodiversity.

The topics of this Special Issue include, but are not limited to, the evaluation of I) the potential effect of plant growth-promoting bacteria in the promotion of plant growth; II) arbuscular mycorrhizal fungi colonization and sporulation potential in plants; III) the interaction between arbuscular mycorrhizal fungi and plant growth-promoting bacteria; and IV) their role in plant growth and protection against different biotic and abiotic stresses.

We welcome all scientific works (original research papers, perspectives, hypotheses, reviews, modeling approaches, and methods).

Dr. Loretta Pace
Dr. Rihab Djebaili
Guest Editors

Manuscript Submission Information

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Keywords

plant growth-promoting bacteria
arbuscular mycorrhizal fungi
plant growth and protection
biotic and abiotic stress
sustainable agriculture
inoculation

Published Papers (7 papers)

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Research

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17 pages, 2874 KiB

Open AccessArticle

Onion Fusarium Basal Rot Disease Control by Arbuscular Mycorrhizal Fungi and Trichoderma harzianum

by Abdulaziz Yağmur, Semra Demir, Sirel Canpolat, Younes Rezaee Danesh, Beatrice Farda, Rihab Djebaili, Loretta Pace and Marika Pellegrini

Plants 2024, 13(3), 386; https://doi.org/10.3390/plants13030386 - 28 Jan 2024

Cited by 1 | Viewed by 1033

Abstract

Soilborne pathogens reduce 60% of the yield of onion crops. A common fungal pathogen causing wilt disease and severe losses is Fusarium basal rot (FBR). In this study, the combination of Arbuscular Mycorrhizal Fungi (AMF) with Trichoderma harzianum was investigated against FBR. Onion samples were collected from the Ankara–Polatlı region. Among the isolates, isolate S6 was identified as F. oxysporum f. sp. cepae (FOC) using morphological and molecular methods and pathogenicity tests. Different combinations of AMF (Funneliformis mosseae pure strain and the commercial AMF) and T. harzianum were inoculated on susceptible onion cultivars (Seç, Gence, and Şampiyon). The effects of the treatments on FOC biocontrol were studied under growth chamber conditions. The results showed that Şampiyon was the most resistant, while Gence was the most susceptible to basal rot disease. Different colonization rates (8.91–24%), spore densities (16.4–50.4 spore/10 g soil), and the extent to which a plant needs mycorrhizal conditions to grow to its maximum potential (i.e., mycorrhizal dependencies—18.3–51.9%) were recorded by treatment. Both single and combined applications of AMF and Trichoderma applications suppressed FOC. Suppressive effects were more pronounced when the F. mosseae pure strain was used alone (when F. mosseae was used, disease severity decreased from 90 to 68%, p < 0.05). The F. mosseae pure strain also showed the best plant growth promotion and phosphorus content release. The results indicate an interesting potential use of F. mosseae and the combination of AMF with T. harzianum in the management of FOC in onions. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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15 pages, 1266 KiB

Open AccessArticle

The Beneficial Effects of Inoculation with Selected Nodule-Associated PGPR on White Lupin Are Comparable to Those of Inoculation with Symbiotic Rhizobia

by Abdelhakim Msaddak, Miguel A. Quiñones, Mohamed Mars and José J. Pueyo

Plants 2023, 12(24), 4109; https://doi.org/10.3390/plants12244109 - 8 Dec 2023

Viewed by 900

Abstract

Nodule endophytes and associated bacteria are non-symbiotic bacteria that colonize legume nodules. They accompany nodulating rhizobia and can form beneficial associations, as some of them are plant growth-promoting rhizobacteria (PGPR) that are able to promote germination and plant growth and increase tolerance to biotic and abiotic stress. White lupin (Lupinus albus) is a legume crop that is gaining relevance as a suitable alternative to soybean as a plant protein source. Eleven nodule-associated bacteria were isolated from white lupin nodules grown in a Tunisian soil. They belonged to the genera Rhizobium, Ensifer, Pseudomonas and Bacillus. Their plant growth-promoting (PGP) and enzymatic activities were tested in vitro. Strains Pseudomonas sp., L1 and L12, displayed most PGP activities tested, and were selected for in planta assays. Inoculation with strains L1 or L12 increased seed germination and had the same positive effects on all plant growth parameters as did inoculation with symbiotic Bradyrhizobium canariense, with no significant differences among treatments. Inoculation with efficient nitrogen-fixing rhizobia must compete with rhizobia present in the soil that sometimes nodulate efficiently but fix nitrogen poorly, leading to a low response to inoculation. In such cases, inoculation with highly effective PGPR might represent a feasible alternative to boost crop productivity. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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22 pages, 3767 KiB

Open AccessArticle

Beneficial Interactive Effects Provided by an Arbuscular Mycorrhizal Fungi and Yeast on the Growth of Oenothera picensis Established on Cu Mine Tailings

by Rodrigo Pérez, Yasna Tapia, Mónica Antilén, Antonieta Ruiz, Paula Pimentel, Christian Santander, Humberto Aponte, Felipe González and Pablo Cornejo

Plants 2023, 12(23), 4012; https://doi.org/10.3390/plants12234012 - 29 Nov 2023

Cited by 1 | Viewed by 844

Abstract

Phytoremediation, an environmentally friendly and sustainable approach for addressing Cu-contaminated environments, remains underutilized in mine tailings. Arbuscular mycorrhizal fungi (AMF) play a vital role in reducing Cu levels in plants through various mechanisms, including glomalin stabilization, immobilization within fungal structures, and enhancing plant tolerance to oxidative stress. Yeasts also contribute to plant growth and metal tolerance by producing phytohormones, solubilizing phosphates, generating exopolysaccharides, and facilitating AMF colonization. This study aimed to assess the impact of AMF and yeast inoculation on the growth and antioxidant response of Oenothera picensis plants growing in Cu mine tailings amended with compost. Plants were either non-inoculated (NY) or inoculated with Meyerozyma guilliermondii (MG), Rhodotorula mucilaginosa (RM), or a combination of both (MIX). Plants were also inoculated with Claroideoglomus claroideum (CC), while others remained non-AMF inoculated (NM). The results indicated significantly higher shoot biomass in the MG-NM treatment, showing a 3.4-fold increase compared to the NY-NM treatment. The MG-CC treatment exhibited the most substantial increase in root biomass, reaching 5-fold that in the NY-NM treatment. Co-inoculation of AMF and yeast influenced antioxidant activity, particularly catalase and ascorbate peroxidase. Furthermore, AMF and yeast inoculation individually led to a 2-fold decrease in total phenols in the roots. Yeast inoculation notably reduced non-enzymatic antioxidant activity in the ABTS and CUPRAC assays. Both AMF and yeast inoculation promoted the production of photosynthetic pigments, further emphasizing their importance in phytoremediation programs for mine tailings. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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24 pages, 23679 KiB

Open AccessArticle

Culturomics and Circular Agronomy: Two Sides of the Same Coin for the Design of a Tailored Biofertilizer for the Semi-Halophyte Mesembryanthemum crystallinum

by Eloísa Pajuelo, Noris J. Flores-Duarte, Salvadora Navarro-Torre, Ignacio D. Rodríguez-Llorente, Enrique Mateos-Naranjo, Susana Redondo-Gómez and José A. Carrasco López

Plants 2023, 12(13), 2545; https://doi.org/10.3390/plants12132545 - 4 Jul 2023

Cited by 2 | Viewed by 1154

Abstract

According to the EU, the global consumption of biomass, fossil fuels, metals, and minerals is expected to double by 2050, while waste will increase by 70%. In this context, the Circular Economy Action Plan (CEAP) intends to integrate development and sustainability. In this regard, tailored biofertilizers based on plant growth-promoting bacteria (PGPB) can improve plant yield with fewer inputs. In our project, an autochthonous halophyte of the Andalusian marshes, namely Mesembryanthemum crystallinum, was selected for its interest as a source of pharmaceuticals and nutraceuticals. The aim of this work was to use a culturomics approach for the isolation of specific PGPB and endophytes able to promote plant growth and, eventually, modulate the metabolome of the plant. For this purpose, a specific culture medium based on M. crystallinum biomass, called Mesem Agar (MA), was elaborated. Bacteria of three compartments (rhizosphere soil, root endophytes, and shoot endophytes) were isolated on standard tryptone soy agar (TSA) and MA in order to obtain two independent collections. A higher number of bacteria were isolated on TSA than in MA (47 vs. 37). All the bacteria were identified, and although some of them were isolated in both media (Pseudomonas, Bacillus, Priestia, Rosellomorea, etc.), either medium allowed the isolation of specific members of the M. crystallinum microbiome such as Leclercia, Curtobacterium, Pantoea, Lysinibacillus, Mesobacillus, Glutamicibacter, etc. Plant growth-promoting properties and extracellular degrading activities of all the strains were determined, and distinct patterns were found in both media. The three best bacteria of each collection were selected in order to produce two different consortia, whose effects on seed germination, root colonization, plant growth and physiology, and metabolomics were analyzed. Additionally, the results of the plant metabolome revealed a differential accumulation of several primary and secondary metabolites with pharmaceutical properties. Overall, the results demonstrated the feasibility of using “low cost media” based on plant biomass to carry out a culturomics approach in order to isolate the most suitable bacteria for biofertilizers. In this way, a circular model is established in which bacteria help plants to grow, and, in turn, a medium based on plant wastes supports bacterial growth at low prices, which is the reason why this approach can be considered within the model of “circular agronomy”. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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19 pages, 1624 KiB

Open AccessArticle

Isolation of Methane Enriched Bacterial Communities and Application as Wheat Biofertilizer under Drought Conditions: An Environmental Contribution

by Adoración Barros-Rodríguez, Carlos García-Gálvez, Pamela Pacheco, Marina G. Kalyuzhnaya and Maximino Manzanera

Plants 2023, 12(13), 2487; https://doi.org/10.3390/plants12132487 - 29 Jun 2023

Cited by 1 | Viewed by 1360

Abstract

The search for methanotrophs as plant-growth-promoting rhizobacteria (PGPR) presents an important contribution to mitigating the impact of global warming by restoring the natural soil potential for consuming methane while benefiting plants during droughts. Our in silico simulations suggest that water, produced as a byproduct of methane oxidation, can satisfy the cell growth requirement. In addition to water, methanotrophs can produce metabolites that stimulate plant growth. Considering this, we proposed that applying methanotrophs as PGPR can alleviate the effect of droughts on crops, while stimulating atmospheric methane consumption. In this work, we isolated a series of methanotrophic communities from the rhizospheres of different crops, including Italian sweet pepper and zucchini, using an atmosphere enriched with pure methane gas, to determine their potential for alleviating drought stress in wheat plants. Subsequently, 23 strains of nonmethanotrophic bacteria present in the methanotrophic communities were isolated and characterized. We then analyzed the contribution of the methane-consuming consortia to the improvement of plant growth under drought conditions, showing that some communities contributed to increases in the wheat plants’ lengths and weights, with statistically significant differences according to ANOVA models. Furthermore, we found that the presence of methane gas can further stimulate the plant–microbe interactions, resulting in larger plants and higher drought tolerance. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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Review

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38 pages, 576 KiB

Open AccessReview

The Roles of Plant-Growth-Promoting Rhizobacteria (PGPR)-Based Biostimulants for Agricultural Production Systems

by Wenli Sun, Mohamad Hesam Shahrajabian and Ali Soleymani

Plants 2024, 13(5), 613; https://doi.org/10.3390/plants13050613 - 23 Feb 2024

Viewed by 1526

Abstract

The application of biostimulants has been proven to be an advantageous tool and an appropriate form of management towards the effective use of natural resources, food security, and the beneficial effects on plant growth and yield. Plant-growth-promoting rhizobacteria (PGPR) are microbes connected with plant roots that can increase plant growth by different methods such as producing plant hormones and molecules to improve plant growth or providing increased mineral nutrition. They can colonize all ecological niches of roots to all stages of crop development, and they can affect plant growth and development directly by modulating plant hormone levels and enhancing nutrient acquisition such as of potassium, phosphorus, nitrogen, and essential minerals, or indirectly via reducing the inhibitory impacts of different pathogens in the forms of biocontrol parameters. Many plant-associated species such as Pseudomonas, Acinetobacter, Streptomyces, Serratia, Arthrobacter, and Rhodococcus can increase plant growth by improving plant disease resistance, synthesizing growth-stimulating plant hormones, and suppressing pathogenic microorganisms. The application of biostimulants is both an environmentally friendly practice and a promising method that can enhance the sustainability of horticultural and agricultural production systems as well as promote the quantity and quality of foods. They can also reduce the global dependence on hazardous agricultural chemicals. Science Direct, Google Scholar, Springer Link, CAB Direct, Scopus, Springer Link, Taylor and Francis, Web of Science, and Wiley Online Library were checked, and the search was conducted on all manuscript sections in accordance with the terms Acinetobacter, Arthrobacter, Enterobacter, Ochrobactrum, Pseudomonas, Rhodococcus, Serratia, Streptomyces, Biostimulants, Plant growth promoting rhizobactera, and Stenotrophomonas. The aim of this manuscript is to survey the effects of plant-growth-promoting rhizobacteria by presenting case studies and successful paradigms in various agricultural and horticultural crops. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

16 pages, 1136 KiB

Open AccessReview

Plant Growth-Promoting Soil Bacteria: Nitrogen Fixation, Phosphate Solubilization, Siderophore Production, and Other Biological Activities

by Anna M. Timofeeva, Maria R. Galyamova and Sergey E. Sedykh

Plants 2023, 12(24), 4074; https://doi.org/10.3390/plants12244074 - 5 Dec 2023

Cited by 4 | Viewed by 2735

Abstract

This review covers the literature data on plant growth-promoting bacteria in soil, which can fix atmospheric nitrogen, solubilize phosphates, produce and secrete siderophores, and may exhibit several different behaviors simultaneously. We discuss perspectives for creating bacterial consortia and introducing them into the soil to increase crop productivity in agrosystems. The application of rhizosphere bacteria—which are capable of fixing nitrogen, solubilizing organic and inorganic phosphates, and secreting siderophores, as well as their consortia—has been demonstrated to meet the objectives of sustainable agriculture, such as increasing soil fertility and crop yields. The combining of plant growth-promoting bacteria with mineral fertilizers is a crucial trend that allows for a reduction in fertilizer use and is beneficial for crop production. Full article

(This article belongs to the Special Issue Plant Growth-Promoting Bacteria and Arbuscular Mycorrhizal Fungi)

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