Rhizosphere Microbial Community

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Plant Microbe Interactions".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 18053

Special Issue Editor

Department of Life Science, Dongguk University, Goyang 10326, Republic of Korea
Interests: symbiosis; plant growth promoting rhizobacteria (PGPR); rhizosphere; endophytes; plant-microbe interactions
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Special Issue Information

Dear Colleagues,

The bacterial community found in the rhizosphere, known for its colonization around the roots due to availability of nutrients, plays an important role in plant growth and adaptability both directly or indirectly. Various bacteria promote plant root growth to establish their ecological niche in the rhizosphere. Rhizobacteria are involved in plant-growth promotion and are often utilized to improve crop health and productivity. The rhizosphere microbe community has been the focus of extensive research during recent decades due to its impact on plant sustainability.

More than 99% of soil bacterial species are assumed to be uncultured bacteria. The development of a next-generation sequencing (NGS) technique has allowed us to explore bacterial diversity, contributing to give additional information about culturable and non-culturable plant-associated bacteria. In recent years, many studies have shown that bacterial population associated with plants has allowed the identification of a large number of novel genus and species. Moreover, whole genome sequencing has revealed a great deal about the metabolism and relationship between bacteria and their host.

This Special Issue seeks contributions that explore the native bacterial community and diversity in the rhizosphere of plants, with the aim of sharing new findings on microorganisms’ interactions with plants in the rhizosphere environment. Moreover, it will consist of articles covering the isolation and characterization of microbes, genomic analyses and agronomic applications. Submissions of research articles, review articles, or short communications related to rhizosphere microbial community are all welcome, and will help us to make unexpected new discoveries in this area.

Dr. Taegun Seo
Guest Editor

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Published Papers (8 papers)

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Research

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13 pages, 2030 KiB  
Article
Gender Effects of Dioecious Plant Populus cathayana on Fungal Community and Mycorrhizal Distribution at Different Arid Zones in Qinghai, China
by Zhen Li, Na Wu, Ting Liu and Ming Tang
Microorganisms 2023, 11(2), 270; https://doi.org/10.3390/microorganisms11020270 - 19 Jan 2023
Cited by 3 | Viewed by 1500
Abstract
Dioecious plants have a wide distribution in nature and gender effect may cause significant alterations in rhizosphere fungal community and soil properties. However, little is known regarding changes in response to dioecious plants. This study aimed to investigate the effects that the dioecious [...] Read more.
Dioecious plants have a wide distribution in nature and gender effect may cause significant alterations in rhizosphere fungal community and soil properties. However, little is known regarding changes in response to dioecious plants. This study aimed to investigate the effects that the dioecious plant, Populus cathayana, and regions of different arid levels have on the fungal community, mycorrhizal distribution, soil enzymatic activities, and nutrient contents. This study characterized fungal and soil factors from the rhizosphere of the dioecious plant Populus cathayana located in the semi-humid regions (Chengguan), semi-arid regions (Sining, Haiyan) and arid regions (Ulan, Chaka). Rhizosphere soil was collected from each site and gender, and the total fungal genomic DNA was extracted. DNA amplicons from fungal ITS region were generated and subjected to Illumina Miseq sequencing. A total of 5 phyla, 28 classes, 92 orders, 170 families, and 380 genuses were observed. AMF distribution peaked at Chaka, which did not conform to the trend. Gender had significant effects on fungal communities: there were obvious differences in fungal OTUs between genders. Alpha diversity raised at first and then decreased. RDA results showed available P, available K, pH, ALP activity, ammonium N, EC, water content and catalase activity were the key contributors in sample areas. Our results suggested potential interaction effects between plant gender and fungal community. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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18 pages, 2378 KiB  
Article
Bacteria Associated with the Roots of Common Bean (Phaseolus vulgaris L.) at Different Development Stages: Diversity and Plant Growth Promotion
by Ricardo Rocha, Tiago Lopes, Cátia Fidalgo, Artur Alves, Paulo Cardoso and Etelvina Figueira
Microorganisms 2023, 11(1), 57; https://doi.org/10.3390/microorganisms11010057 - 24 Dec 2022
Cited by 3 | Viewed by 2342
Abstract
Current agricultural methodologies are vulnerable to erratic climate and are dependent on cost-intensive fertilization to ensure high yields. Sustainable practices should be pursued to ensure food security. Phaseolus vulgaris L. is one of the most produced legumes worldwide and may be an alternative [...] Read more.
Current agricultural methodologies are vulnerable to erratic climate and are dependent on cost-intensive fertilization to ensure high yields. Sustainable practices should be pursued to ensure food security. Phaseolus vulgaris L. is one of the most produced legumes worldwide and may be an alternative to reduce the environmental impact of meat production as a reliable source of high-quality protein. Plant growth-promoting rhizobacteria (PGPR) are emerging as a sustainable option to increase agricultural production. To understand the dynamics between plants and microorganisms, the culturable microbiota of bean roots was isolated and identified at distinct stages of plant development (early and late vegetative growth, flowering, and pod) and root compartments (rhizoplane, endosphere, and nodules). Diversity and abundance of bacteria associated with root compartments differed throughout the plant life cycle. Bacterial plant growth promotion (PGP) and protection abilities (indole-3-acetic acid production, siderophore synthesis, and antifungal activity) were assessed and associated with plant phenology, demonstrating that among the bacteria associated with plant roots, several strains had an active role in the response to plant biological needs at each stage. Several strains stood out for their ability to display one or more PGP traits, being excellent candidates for efficient stage-specific biostimulants for application in precision agriculture. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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15 pages, 2931 KiB  
Article
Higher-Quality Pumpkin Cultivars Need to Recruit More Abundant Soil Microbes in Rhizospheres
by Yan Sun, Ziyue Huang, Siyu Chen, Da Yang, Xinru Lin, Wenjun Liu and Shangdong Yang
Microorganisms 2022, 10(11), 2219; https://doi.org/10.3390/microorganisms10112219 - 09 Nov 2022
Cited by 1 | Viewed by 1535
Abstract
Two different qualities of pumpkin, cultivars G1519 and G1511, were grown in the same environment under identical management. However, their qualities, such as the contents of total soluble solids, starch, protein, and vitamin C, were significantly different. Do rhizospheric microbes contribute to pumpkin [...] Read more.
Two different qualities of pumpkin, cultivars G1519 and G1511, were grown in the same environment under identical management. However, their qualities, such as the contents of total soluble solids, starch, protein, and vitamin C, were significantly different. Do rhizospheric microbes contribute to pumpkin quality? To answer this question, this study investigated the soil microbial compositions in the rhizospheres of different quality pumpkin cultivars to determine the differences in these soil microbial compositions and thus determine how soil microbes may affect pumpkin quality. Firstly, a randomized complete block design with two pumpkin cultivars and three replications was performed in this study. The soil microbial compositions and structures in the rhizospheres of the two pumpkin cultivars were analyzed using a high-throughput sequencing technique. In comparison with the low-quality pumpkin cultivar (G1519), higher microbial diversity and richness could be found in the rhizospheres of the high-quality pumpkin cultivar (G1511). The results showed that there were significant differences in the soil bacterial and fungal community compositions in the rhizospheres of the high- and low-quality pumpkin cultivars. Although the compositions and proportions of microorganisms were similar in the rhizospheres of the two pumpkin cultivars, the proportions of Basidiomycota and Micropsalliota in the G1519 rhizosphere were much higher than those in the G1511 rhizosphere. Furthermore, the fungal phylum and genus Rozellomycota and Unclassified_p__Rozellomycota were unique in the rhizosphere of the high-quality pumpkin cultivar (G1511). All the above results indicate that soil microbes were enriched differentially in the rhizospheres of the low- and high-quality pumpkin cultivars. In other words, more abundant soil microbes were recruited in the rhizosphere of the high-quality pumpkin cultivar as compared to that of the low-quality cultivar. Rozellomycota and Unclassified_p__Rozellomycota may be functional microorganisms relating to pumpkin quality. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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13 pages, 3317 KiB  
Article
Responses of Bacterial Community Structure, Diversity, and Chemical Properties in the Rhizosphere Soil on Fruiting-Body Formation of Suillus luteus
by Yixin Zhou, Zhichao Shi, Qiliang Pang, Xiufeng Liang, Hongtao Li, Xin Sui, Chongwei Li and Fuqiang Song
Microorganisms 2022, 10(10), 2059; https://doi.org/10.3390/microorganisms10102059 - 18 Oct 2022
Cited by 3 | Viewed by 1453
Abstract
Mycorrhiza helper bacteria (MHB) play an important role in driving mycorrhizal formation. There are few reports on the relationship between bacteria and fruiting growths. Taking mycorrhizal rhizosphere soil from sporocarps of the S. luteus and non-mycorrhizal rhizosphere soil of the host plant ( [...] Read more.
Mycorrhiza helper bacteria (MHB) play an important role in driving mycorrhizal formation. There are few reports on the relationship between bacteria and fruiting growths. Taking mycorrhizal rhizosphere soil from sporocarps of the S. luteus and non-mycorrhizal rhizosphere soil of the host plant (Larix gmelinii), we measured the bacterial community structure and diversity and chemical properties to clarify the effect of bacteria on fruiting-body formation. The bacterial diversity was significantly higher in mycorrhizal rhizosphere soil (p < 0.05) than that in non-mycorrhizal rhizosphere soil. The relative abundance of Burkholderia, Bradyrhizobium, Pseudomonas, and Rhizobium was significantly higher (p < 0.05) in mycorrhizal rhizosphere soil than in non-mycorrhizal rhizosphere soil. The soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), ammonium nitrogen (AN), available phosphorus (AP), available potassium (AK), and the activity of catalase, urease, and phosphatase in mycorrhizal rhizosphere soil were significantly higher (p < 0.05) than those in non-mycorrhizal rhizosphere soil. A redundancy analysis (RDA) showed that dominant bacteria are closely related to soil enzyme activity and physicochemical properties (p < 0.05). The boletus recruits a large number of bacteria around the plant roots that speed up nutrient transformation and increase the soil nutrient content, providing an important guarantee for mycelium culture and fruiting-body formation. These findings provide ideas for the nutritional supply of boletus sporocarps and lay the theoretical foundation for the efficient artificial cultivation of boletus. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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15 pages, 2259 KiB  
Article
Probiotics Enhance Cereal Yield and Quality and Modify Agrochemical Soil Properties
by Virgilija Gavelienė and Sigita Jurkonienė
Microorganisms 2022, 10(7), 1277; https://doi.org/10.3390/microorganisms10071277 - 23 Jun 2022
Cited by 1 | Viewed by 2619
Abstract
The aim of this study was to determine the influence of microbial biostimulants on wheat and oat growth, grain yield, and grain quality and to evaluate the influence of these probiotics on some soil agrochemical traits in the open field. Active concentrations of [...] Read more.
The aim of this study was to determine the influence of microbial biostimulants on wheat and oat growth, grain yield, and grain quality and to evaluate the influence of these probiotics on some soil agrochemical traits in the open field. Active concentrations of ProbioHumus and NaturGel and their mixtures were selected under laboratory conditions using winter wheat as a reference plant. Probiotics had a biostimulating effect on the development of the underground and aboveground part of winter wheat when 2 µL/g was used for seed priming and 2 mL/100 mL for seedling spraying. Under field conditions, after treatment of soil (2 L/ha), wheat and oat seeds (2 L/t), and plants (2 L/ha) with ProbioHumus and NaturGel, it was found that the yield of the studied cereals increased, on average, by 0.50 t/ha to 1.09 t/ha. ProbioHumus promoted protein accumulation in the investigated cereal grains. The level of microelements in wheat and oat grains increased after treatment of plants with NaturGel. Probiotics improved soil agrochemical properties, such as total and nitrate nitrogen, total and available phosphorus, organic carbon, humic acid, and humus content. In conclusion, plant probiotics can be used as an ecological alternative for growing cereals and improving the agrochemical properties of the soil. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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15 pages, 1917 KiB  
Article
Characteristics and Biological Activity of Exopolysaccharide Produced by Lysobacter sp. MMG2 Isolated from the Roots of Tagetes patula
by Inhyup Kim, Geeta Chhetri, Yoonseop So, Jiyoun Kim and Taegun Seo
Microorganisms 2022, 10(7), 1257; https://doi.org/10.3390/microorganisms10071257 - 21 Jun 2022
Cited by 3 | Viewed by 1893
Abstract
In the present study, exopolysaccharide (EPS) produced by Lysobacter sp. MMG2 (lyEPS) was characterized and purified. The lyEPS-producing strain Lysobacter sp. MMG2 was isolated from the roots of Tagetes patula. When lyEPS was produced in tryptic soy broth with 1% glucose and [...] Read more.
In the present study, exopolysaccharide (EPS) produced by Lysobacter sp. MMG2 (lyEPS) was characterized and purified. The lyEPS-producing strain Lysobacter sp. MMG2 was isolated from the roots of Tagetes patula. When lyEPS was produced in tryptic soy broth with 1% glucose and the lyophilized powder was measured, the yield was found to be 0.67 g/L. The molecular weight (Mw) of lyEPS was 1.01 × 105 Da. Its monosaccharide composition includes 84.24% mannose, 9.73% glucose, 2.55% galactose, 2.77% arabinose, 0.32% xylose, and 0.03% rhamnose. Scanning electron microscopy (SEM) revealed that lyEPS has various round and rough surfaces. Fourier-transform infrared (FTIR) analysis identified its carbohydrate polymer functional groups. Moreover, thermogravimetric analysis of lyEPS revealed two events of mass loss: the first was water loss, which resulted in 3.97% mass loss and the second event occurred at approximately 212 °C. lyEPS could inhibit biofilm-producing pathogenic bacteria without any antimicrobial activity. Furthermore, lyEPS at a concentration of 4 mg/mL could exhibit potent 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging activity (89.25%). These results indicate that lyEPS could be a promising candidate for industrial development if its biological activity is further explored. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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16 pages, 2839 KiB  
Article
An Isolated Arthrobacter sp. Enhances Rice (Oryza sativa L.) Plant Growth
by Geeta Chhetri, Inhyup Kim, Minchung Kang, Yoonseop So, Jiyoun Kim and Taegun Seo
Microorganisms 2022, 10(6), 1187; https://doi.org/10.3390/microorganisms10061187 - 09 Jun 2022
Cited by 13 | Viewed by 2835
Abstract
Rice is a symbol of life and a representation of prosperity in South Korea. However, studies on the diversity of the bacterial communities in the rhizosphere of rice plants are limited. In this study, four bundles of root samples were collected from the [...] Read more.
Rice is a symbol of life and a representation of prosperity in South Korea. However, studies on the diversity of the bacterial communities in the rhizosphere of rice plants are limited. In this study, four bundles of root samples were collected from the same rice field located in Goyang, South Korea. These were systematically analyzed to discover the diversity of culturable bacterial communities through culture-dependent methods. A total of 504 culturable bacteria were isolated and evaluated for their plant growth-promoting abilities in vitro. Among them, Arthrobacter sp. GN70 was selected for inoculation into the rice plants under laboratory and greenhouse conditions. The results showed a significantly positive effect on shoot length, root length, fresh plant weight, and dry plant weight. Moreover, scanning electron microscopic (SEM) images demonstrated the accumulation of bacterial biofilm networks at the junction of the primary roots, confirming the root-colonizing ability of the bacterium. The strain also exhibited a broad spectrum of in vitro antimicrobial activities against bacteria and fungi. Here, we first report the rice plant growth-promoting ability of the Arthrobacter species with the biofilm-producing and antimicrobial activities against plant and human pathogens. Genome analyses revealed features attributable to enhance rice plant growth, including the genes involved in the synthesis of plant hormones, biofilm production, and secondary metabolites. This study revealed that the rhizobacteria isolated from the roots of rice plants have dual potential to be utilized as a plant growth promoter and antimicrobial agent. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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Review

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15 pages, 318 KiB  
Review
The Rhizosphere Microbiome of Ginseng
by Paul H. Goodwin
Microorganisms 2022, 10(6), 1152; https://doi.org/10.3390/microorganisms10061152 - 02 Jun 2022
Cited by 9 | Viewed by 2474
Abstract
The rhizosphere of ginseng contains a wide range of microorganisms that can have beneficial or harmful effects on the plant. Root exudates of ginseng, particularly ginsenosides and phenolic acids, appear to select for particular microbial populations through their stimulatory and inhibitory activities, which [...] Read more.
The rhizosphere of ginseng contains a wide range of microorganisms that can have beneficial or harmful effects on the plant. Root exudates of ginseng, particularly ginsenosides and phenolic acids, appear to select for particular microbial populations through their stimulatory and inhibitory activities, which may account for the similarities between the rhizosphere microbiomes of different cultivated species of Panax. Many practices of cultivation attempt to mimic the natural conditions of ginseng as an understory plant in hilly forested areas. However, these practices are often disruptive to soil, and thus the soil microbiome differs between wild and cultivated ginseng. Changes in the microbiome during cultivation can be harmful as they have been associated with negative changes of the soil physiochemistry as well as the promotion of plant diseases. However, isolation of a number of beneficial microbes from the ginseng rhizosphere indicates that many have the potential to improve ginseng production. The application of high-throughput sequencing to study the rhizosphere microbiome of ginseng grown under a variety of conditions continues to greatly expand our knowledge of the diversity and abundance of those organisms as well as their impacts of cultivation. While there is much more to be learnt, many aspects of the ginseng rhizosphere microbiome have already been revealed. Full article
(This article belongs to the Special Issue Rhizosphere Microbial Community)
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