Rhizosphere Microorganisms—2nd Edition

A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Soil and Plant Nutrition".

Deadline for manuscript submissions: 20 March 2025 | Viewed by 7404

Special Issue Editors


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Guest Editor
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Agricultural University of Shandong, Tai'an 271000, China
Interests: plant rhizosphere microorganisms; plant–microbe interactions
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Guest Editor
North Florida Research and Education Center, University of Florida, Quincy, FL 32351, USA
Interests: microbial ecology; plant–fungal cross-talk; plant–microbial symbiosis; metaomics; genetic engineering; forest microbiome; forage microbiome

Special Issue Information

Dear Colleagues,

Following the publication of the first Special Issue "Rhizosphere Microorganisms" of Agronomy, the Editorial Office is willing to launch a second volume of the Special Issue. The subject, editorial team, and submission process are retained within this volume.

Plant rhizosphere microorganisms can offer protection against pathogens, improve growth, and contribute to plant phenotypic plasticity. Plant-growth-promoting rhizobacteria (PGPR) are beneficial microbes that stably survive and colonize in the rhizosphere of plants. PGPR are a major source of biofertilizer strains which have beneficial effects on crops, such as growth promotion, the inhibition of soil-borne pathogens, and the enhancement of plant tolerance. The beneficial functions of PGPR on plants largely rely on root colonization ability, for which chemotactic motility and biofilm formation on the rhizoplane are the most important colonization processes. This provides a rational basis for increasing the quality of soil and developing sustainable agriculture with less input from fertilizers or pesticides.

Prof. Dr. Zhihong Xie
Dr. Hui-Ling Liao
Guest Editors

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Keywords

  • rhizosphere
  • microorganisms
  • interaction
  • promote
  • resistance

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Published Papers (5 papers)

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Research

26 pages, 13388 KiB  
Article
Nodulating Aeschynomene indica without Nod Factor Synthesis Genes: In Silico Analysis of Evolutionary Relationship
by Mengguang Zhao, Jingyi Dong, Zhenpeng Zhang, Entao Wang, Dandan Wang, Huijie Xie, Chao Wang and Zhihong Xie
Agronomy 2024, 14(6), 1295; https://doi.org/10.3390/agronomy14061295 - 15 Jun 2024
Viewed by 731
Abstract
Aeschynomene indica rhizobia (AIRs) are special classes of bacteria capable of nodulating without nodulation factors and have photosynthetic capacity. With an aim to characterize the structural variations in Bradyrhizobium genomes during its evolution, the genomes of AIRs and the reference Bradyrhizobium strains were [...] Read more.
Aeschynomene indica rhizobia (AIRs) are special classes of bacteria capable of nodulating without nodulation factors and have photosynthetic capacity. With an aim to characterize the structural variations in Bradyrhizobium genomes during its evolution, the genomes of AIRs and the reference Bradyrhizobium strains were compared utilizing molecular biology, bioinformatics, and biochemistry techniques. The presence of symbiotic nitrogen fixation (nif) genes and photosynthetic genes, as well as components of the T3SS (Type III secretion system) and T3CP (Type III chaperone) in the genome of AIRs, was also assessed. Additionally, the origin, evolutionary history, and genes associated with the NF-independent nodulation pattern in AIRs were explored. The results indicate that horizontal gene transfer events have occurred in AIRs, and three distinct origins of AIRs were estimated: early differentiated AIRs, non-symbiotic Bradyrhizobium, and non-AIRs. In contrast to the significant genetic transformations observed in the second and third groups, the first group of AIRs displays a rich evolutionary history, exhibits high species diversity, and primarily relies on vertical transmission of nitrogen fixation and photosynthetic genes. Overall, the findings provide a fundamental theoretical foundation for gaining a deeper understanding of the phylogeny and genealogy of AIRs. Full article
(This article belongs to the Special Issue Rhizosphere Microorganisms—2nd Edition)
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21 pages, 6925 KiB  
Article
Effects of Film Mulching on Soil Microbial Diversity and Community Structure in the Maize Root Zone under Drip Irrigation in Northwest China
by Mengjie Liu, Jiliang Zheng, Quansheng Li, Fei Liang, Xiaoguo Mu, Dongjie Pei, Hongtao Jia and Zhenhua Wang
Agronomy 2024, 14(6), 1139; https://doi.org/10.3390/agronomy14061139 - 27 May 2024
Cited by 1 | Viewed by 1796 | Correction
Abstract
Mulching is a widely used agricultural water conservation measure in the semiarid regions of Northwest China. In order to explore the response process of different film mulching methods to soil microorganisms, we characterized the effect of different film mulching methods on soil microbial [...] Read more.
Mulching is a widely used agricultural water conservation measure in the semiarid regions of Northwest China. In order to explore the response process of different film mulching methods to soil microorganisms, we characterized the effect of different film mulching methods on soil microbial diversity and community structure characteristics in the root zone of drip-irrigated maize during the heading and maturity stages using high-throughput sequencing of 16SrDNA and ITS amplicons combined with bioinformatics analysis. Full mulching (FM) was contrasted to controls of no mulching (NM) and half-mulching (HM), yielding an order of microbial diversity, abundance, and evenness scores of HM > FM > NM. The HM and FM treatments reduced the relative abundance of Proteobacteria and Actinobacteria (the most abundant bacteria) in the bacterial community structure but increased that of Acidobacteria and Chloroflexi. In the fungal community structure, HM decreased the abundance of Sordariomycetes but increased that of Eurotiomycetes (the most abundant fungi). The abundance and community structure of bacteria were significantly correlated with soil temperature and those of fungi with pH. HM improved network complexity and competitive relationships among bacteria, while FM increased the relationship between fungal groups and the symbiosis of fungal communities. HM significantly increased maize yield (20.37% and 6.01% above NM and FM, respectively). In summary, full mulching was more favorable than no mulching for soil microbial diversity and community structure composition, but soil microbial diversity and yield responded better to half-mulching. These results provide a background for improving the yield of drip-irrigated maize and protecting the microbial ecosystems of farmland soils. Full article
(This article belongs to the Special Issue Rhizosphere Microorganisms—2nd Edition)
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17 pages, 3534 KiB  
Article
Effect of Cucumber Continuous Monocropping on Traditional Chinese Medicine Residue through Analysis of Physicochemical Characteristics and Microbial Diversity
by Qingsong Zhao, Jingjing Dong, Zhiyong Yan, Ling Xu and Ake Liu
Agronomy 2024, 14(4), 709; https://doi.org/10.3390/agronomy14040709 - 28 Mar 2024
Cited by 1 | Viewed by 983
Abstract
The use of traditional Chinese medicine (TCM) residue as a crop culture substrate has unique advantages in alleviating the obstacles associated with continuous monocropping, such as increasing production, improving quality and alleviating pests and diseases. However, the effect of TCM residue application on [...] Read more.
The use of traditional Chinese medicine (TCM) residue as a crop culture substrate has unique advantages in alleviating the obstacles associated with continuous monocropping, such as increasing production, improving quality and alleviating pests and diseases. However, the effect of TCM residue application on substrates in continuous monocropping practices has not been determined. In this study, the cucumber variety “Jinyou No. 10” was used as the material, and fermented TCM residue, vermiculite and perlite were used as organic substrates (3:1:1). The cucumbers were cultivated on substrates for different durations of continuous monocropping, which were the first cropping cycle (A1), second cropping cycle (A2), third cropping cycle (A3) and fourth cropping cycle (A4). The control (A0) was the substrate sample without any crop planted in it. After the cucumbers were harvested, substrate samples (areas around the cucumber roots) were collected. The physiochemical properties of the cultivated substrates were determined, and the microbial community structures were analyzed through 16S rRNA and ITS sequencing. The physiochemical indices of the substrates with different durations of continuous monocropping (A1–A4) were significantly different than those of the control (A0) substrate. Moreover, the continuous cropping of cucumber had greater effects on fungal communities than on bacterial communities. Bacterial community structure analysis revealed a greater proportion of important bacterial taxa (Proteobacteria, Chloroflexi, and Nitrospirae) in the continuous monocropping substrates than in the A0 substrate. For the fungal community, Ascomycota accounted for the largest percentage of the fungal community in all the samples. The diversity of the microbial community was found to be influenced primarily by electrical conductivity, organic matter content, pH and total potassium content according to the correlation analysis of physicochemical properties and relative abundance of the microbial community. Our study would provide a basis for addressing persistent challenges in continuous cropping and for obtaining the utmost benefit from using TCM organic residue waste. Full article
(This article belongs to the Special Issue Rhizosphere Microorganisms—2nd Edition)
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17 pages, 6335 KiB  
Article
Effect of Nitrogen Addition on Tiger Nut (Cyperus esculentus L.) Rhizosphere Microbial Diversity and Drive Factions of Rhizosphere Soil Multifunctionality in Sandy Farmland
by Xu Zheng, Jun Chen, Jianguo Liu, Zhibo Cheng, Luhua Li and Jiaping Wang
Agronomy 2024, 14(2), 368; https://doi.org/10.3390/agronomy14020368 - 14 Feb 2024
Viewed by 1536
Abstract
Nitrogen (N) is an essential element both affecting rhizosphere microorganisms within soil and supporting plant nutrition; however, little is known about how the rhizosphere microbial community composition of tiger nut in sandy soil responds to nitrogen addition. In this study, high-throughput sequencing technology [...] Read more.
Nitrogen (N) is an essential element both affecting rhizosphere microorganisms within soil and supporting plant nutrition; however, little is known about how the rhizosphere microbial community composition of tiger nut in sandy soil responds to nitrogen addition. In this study, high-throughput sequencing technology is employed to analyze the shifts in composition and co-occurrence networks of rhizosphere microbial communities in tiger nut after nitrogen addition in sandy farmland. Results reveal that nitrogen addition significantly increases several soil parameters, including total organic matter (SOC, 32.2%), total nitrogen (TN, 46.2%), alkali-hydro nitrogen (AN, 92.7%), β-1,4-glucosidase (BG, 12.6%), L-leucine aminopeptidase (LAP, 8.62%), β-1,4-xylosidase(XYL, 25.6%), and β-1,4-N-acetylglucosaminidase (NAG, 32.3%). Meanwhile, bacterial α-diversity decreases with nitrogen addition, while fungi remain unaffected. Network analysis indicates a reduction in connections between microorganisms; however, increasing stability is observed in the interaction network after nitrogen addition. Importantly, nitrogen addition leads to the enhancement of rhizosphere soil multifunctionality, with fungal diversity identified as the primary driver of soil multifunctionality. The positive impact of microbial diversity on soil multifunctionality outweighs the relative negative effects. This study sheds light on the nuanced effects of nitrogen addition on rhizosphere microbial diversity and its consequent impact on soil multifunctionality, with Acidobacteria, Proteobacteria and Ascomycota having positive effects, providing a comprehensive understanding of the complex environmental–plant–soil–microbe interactions in sandy farmland ecosystems. Full article
(This article belongs to the Special Issue Rhizosphere Microorganisms—2nd Edition)
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21 pages, 13816 KiB  
Article
Biological Control Effect of Antagonistic Bacteria on Potato Black Scurf Disease Caused by Rhizoctonia solani
by Qingqing Lan, Yang Liu, Rongrong Mu, Xuetao Wang, Qian Zhou, Rehmat Islam, Xu Su and Yongqiang Tian
Agronomy 2024, 14(2), 351; https://doi.org/10.3390/agronomy14020351 - 8 Feb 2024
Cited by 2 | Viewed by 1803
Abstract
Potato black scurf, caused by Rhizoctonia solani, is a severe soil-borne disease that affects the quality and production of potatoes worldwide. In our study, we used Paenibacillus polymyxa YF and Bacillus amyloliquefaciens HT to determine the antagonistic ability of R. solani, [...] Read more.
Potato black scurf, caused by Rhizoctonia solani, is a severe soil-borne disease that affects the quality and production of potatoes worldwide. In our study, we used Paenibacillus polymyxa YF and Bacillus amyloliquefaciens HT to determine the antagonistic ability of R. solani, with a particular focus on the antagonistic action of P. polymyxa YF to R. solani and its biocontrol effect on potato black scurf. In fermentation, filtrate assay, 50% filtrate of P. polymyxa YF and B. amyloliquefaciens HT inhibited the growth of R. solani by 85.55% and 82.86%, respectively. Microscopic observations showed notable morphological changes with mycelial collapse, atrophy, and deformation following treatment with the antagonistic filtrates. Moreover, cell membrane permeability results showed increased conductivity in bacteria-treated samples compared to the control. P. polymyxa YF exhibited stable colonization on potato plants and secreted various extracellular enzymes (protease, amylase, and cellulase), along with the synthetic substances with growth-promoting effects, such as siderophores and Indole-3-acetic acid (IAA). Whether it is in the excised tissue inoculation or potted experiment, the negative control showed the highest rank of disease symptoms. In the pot experiment, after YF treatment, physiological parameters showed remarkable changes in plant height, root length, stem thickness, and dry and fresh weight. Compared to blank control, the activities of the four resistant enzymes increased significantly in the P. polymyxa YF treatment group. The upregulation in the P. polymyxa YF group was 4.04, 0.54, 0.46, and 3.10 times, respectively. PCR analysis identified genes in both bacterial strains coding for antimicrobial lipopeptides, including fenB, ituC, and srfAA, which are associated with fengycin, iturin, and surfactin synthesis. These findings demonstrated that P. polymyxa YF has a prominent antagonistic effect on R. solani, suggesting its potential as an effective biological control agent for controlling potato black scurf. Full article
(This article belongs to the Special Issue Rhizosphere Microorganisms—2nd Edition)
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