Control Of Root Rot Research Articles

Flg22-facilitated PGPR colonization in root tips and control of root rot.

Plant root border cells (RBCs) prevent the colonization of plant growth-promoting rhizobacteria (PGPR) at the root tip, rendering the PGPR unable to effectively control pathogens infecting the root tip. In this study, we engineered four strains of Pseudomonas sp. UW4, a typical PGPR strain, each carrying an enhanced green fluorescent protein (EGFP)-expressing plasmid. The UW4E strain harboured only the plasmid, whereas the UW4E-flg22 strain expressed a secreted EGFP-Flg22 fusion protein, the UW4E-Flg(flg22) strain expressed a non-secreted Flg22, and the UW4E-flg22-D strain expressed a secreted Flg22-DNase fusion protein. UW4E-flg22 and UW4E-flg22-D, which secreted Flg22, induced an immune response in wheat RBCs and colonized wheat root tips, whereas the other strains, which did not secrete Flg22, failed to elicit this response and did not colonize wheat root tips. The immune response revealed that wheat RBCs synthesized mucilage, extracellular DNA, and reactive oxygen species. Furthermore, the Flg22-secreting strains showed a 33.8%-93.8% higher colonization of wheat root tips and reduced the root rot incidence caused by Rhizoctonia solani and Fusarium pseudograminearum by 24.6%-35.7% compared to the non-Flg22-secreting strains in pot trials. There was a negative correlation between the incidence of wheat root rot and colonization of wheat root tips by these strains. In contrast, wheat root length and dry weight were positively correlated with the colonization of wheat root tips by these strains. These results demonstrate that engineered secretion of Flg22 by PGPR is an effective strategy for controlling root rot and improving plant growth.

In-Furrow Application of Biologicals for Control of Rhizoctonia Diseases in Snap Bean

Florida ranks first in the production of fresh-market snap bean in the United States. Rhizoctonia diseases, including damping-off and root rot caused by Rhizoctonia solani, are important diseases in snap bean, particularly if there is heavy rainfall during the first month after seeding. Growers usually use seeds treated with fungicides to control soilborne pathogens including R. solani. However, there are concerns about resistance development in R. solani and the impacts of chemicals on the environment. In this study, three biological products (Howler, Theia, and Double Nickel LC) applied as an in-furrow spray at seeding and/or foliar sprays after emergence were evaluated in the field for their efficacy in controlling R. solani on snap bean. When nontreated seeds were used, Howler at 5 lb./acre and Double Nickel LC at 16 fl. oz./acre each applied as an in-furrow spray at seeding significantly ( P < 0.05) reduced disease incidence compared with the untreated control. However, weekly foliar sprays after emergence showed effectiveness in disease reduction only at a high inoculum level. The highest disease reduction of 95.4% was observed in the treatment with Howler at 5 lb./acre in the 2022 trial, and 32.8% for Double Nickel LC was observed at 16 fl. oz./acre in 2023. Both biologicals also significantly increased the pod yield, by 85.6% with Howler in 2022 and doubled by Double Nickel LC in 2023 when compared with the untreated control. Results from these field trials reveal the potential of these biologicals in the control of Rhizoctonia root rot in snap bean production.

Mitigating root rot in Panax notoginseng: The synergistic effects of biochar and Chaetomium globosum YIM PH30719

Root rot is the main soilborne disease that causes the replant failure of Panax notoginseng, a famous medicinal plant in Asia. Biochar and biocontrol agents have been shown to reduce replant failure separately; however, a knowledge gap still exists regarding the effectiveness and mechanisms of their combined application on the root rot incidence of P. notoginseng. In this study, we conducted a pot experiment using a randomized block design, biochar derived from tobacco stems was applied at 0, 1, 2, and 3 % (T0, T1, T2, T3) to the soil that cultivating P. notoginseng for 10 years continuously; moreover, Chaetomium globosum YIM PH30719, a newly screened biocontrol strain, was applied at 0, 1.0×107, and 1.0×1010 cfu·mL−1 (C0, C1, C2) to the soil. Six months post-transplantation of P. notoginseng seedlings, root rot incidence, soil physicochemical properties, fungal communities, and abundance of the primary pathogen Fusarium oxysporum were investigated. The results showed that, comparing with the single application of YIM PH30719, the combined application with biochar was more efficient in reducing the root rot incidence (P<0.05). P. notoginseng experienced a root rot incidence of 65.4 % under the T0+C0 treatment, however, under T3+C2 treatment, the root rot incidence was only 5.6 % (P<0.05). The reduction in root rot incidence might be linked to changes in soil pH, organic matter, and essential nutrient contents, as well as the increased soil fungal diversity and the relative abundance (RA) of beneficial Chaetomium and Trichoderma, and the decreased RA of pathogenic Fusarium and Alternaria. Consequently, the joint use of biochar and biocontrol agents (YIM PH30719) synergistically decreased the occurrence of root rot by modifying soil physicochemical characteristics and fungal communities. Since root rot is commonly found in agriculture, the results of this study may help in controlling root rot disease in other crops.

Herbal materials used as soil amendments alleviate root rot of Panax ginseng

Root rot is a serious soil-borne fungal disease that seriously affects the yield and quality of Panxa ginseng. To develop a sustainable strategy for alleviating ginseng root rot, an herb-based soil amendment is suggested in this study. Mixed powers of medicinal herbs (MP) and corn stalks (CS) were used as soil amendments, respectively, along with a control group (CK) without treatment. The application of MP and CS led to significant relief from ginseng root rot. The disease index (%) represents both the incidence rate and symptom severity of the disease. The disease index of the MP and CS group was 18.52% and 25.93%, respectively, lower than that of CK (40.74%). Correspondingly, three soil enzyme activities improved; the antifungal components in the soil increased; and the relative abundances of root rot pathogens decreased in response to MP Soil enzyme activities were negatively correlated with disease grades. MP group also led to possible interactive changes in the communities of soil fungi and chemical components. In conclusion, our results suggest that the use of herb-based soil amendments has significant potential as an ecological and effective approach to controlling root rot disease of ginseng by the changing rhizosphere fungal community and soil compositions.

Development of Potting Media from Composted Organic Food Waste Supplemented with Trichoderma asperellum and Talaromyces tratensis for Control of Root and Stem-End Rot in Chinese Kale (Brassica oleracea)

Development of Potting Media from Composted Organic Food Waste Supplemented with Trichoderma asperellum and Talaromyces tratensis for Control of Root and Stem-End Rot in Chinese Kale (Brassica oleracea)

Exogenous Application of dsRNA—Inducing Silencing of the Fusarium oxysporum Tup1 Gene and Reducing Its Virulence

Fusarium oxysporum is a widespread soil-borne fungal pathogen that can infect various plants, causing wilt and root rot diseases. The root rot disease of Atractylodes macrocephala caused by F. oxysporum is among the most serious diseases associated with continuous cropping, significantly hindering its sustainable development. In this study, we aimed to investigate the effect of exogenous application of double-stranded RNA (dsRNA) on silencing the F. oxysporum Tup1 gene to reduce its virulence and to evaluate its potential application in controlling root rot disease in A. macrocephala. The Tup1 gene was amplified from the F. oxysporum genome, and different lengths of Tup1-dsRNA were designed and synthesized. The uptake of dsRNA by the fungus was verified using Tup1-dsRNA labeled with fluorescein, and in vitro dsRNA treatment experiments were conducted to assess its impact on the growth and virulence of F. oxysporum. Additionally, Tup1-dsRNA was applied to the roots of A. macrocephala to evaluate its effectiveness in controlling root rot disease. The experimental results showed that F. oxysporum could effectively uptake exogenously applied Tup1-dsRNA, significantly reducing Tup1 gene expression. All lengths of Tup1-dsRNA inhibited fungal growth and caused morphological changes in the fungal hyphae. Further plant experiments and Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR) analysis indicated that Tup1-dsRNA treatment significantly reduced the incidence of root rot disease in A. macrocephala, which was supported by the reduction in peroxidase (POD) and catalase (CAT) enzyme activities, malondialdehyde (MDA) content, and proline (Pro) levels in treated root tissues. This study demonstrated that exogenous dsRNA could reduce the virulence of F. oxysporum by silencing the Tup1 gene and effectively mitigate the root rot disease it causes in A. macrocephala. The successful application of Tup1-dsRNA provided strong evidence for the potential of RNA interference (RNAi) technology in plant disease control. Future research could further optimize the design and application of dsRNA to enhance its practical value in agriculture.

Revolutionizing Garden Pea Yield: A Synergistic Strategy with Plant Extracts, Bio-control Agents and Fungicides for Root Rot Disease Management and Optimal Productivity

Background: Pea, a vegetable crop cultivated in cooler regions globally, holds substantial economic significance in India. Unfortunately, root rot poses a significant challenge, especially during the early stages of plant growth, with Fusarium solani f. sp. pisi identified as the causative agent. To address this issue, a comprehensive study was conducted over two consecutive years, evaluating the efficacy of various plant extracts, bioagents and fungicides, both in field and laboratory settings, to control root rot in pea. Methods: A field experiment was conducted at Rajasthan Agricultural Research Institute, Jaipur in the Rabi seasons of 2021-22 and 2022-23 aimed to develop a sustainable strategy to gather valuable insights and observations throughout the growing seasons to combat root rot in pea crops, specifically using the susceptible variety Arkel. Result: Among all fungicides, plant extracts and bio-control agents that demonstrated efficacy in laboratory settings were subsequently evaluated in real-field conditions. In field condition seed treatment with tebuconazole 50%+ trifloxystrobin 25% at 0.1% along with soil application of neem cake at 5q/ha was found best with minimum disease incidence and maximum pod yield (75.80 q/ha). Among these treatments, neem cake was the most effective in reducing the incidence of root rot in peas compared to the application of mustard cake.

Assessing Seed Treatments to Control Sudden Death Syndrome Caused by Fusarium virguliforme and Seedling and Root Disease Caused by Rhizoctonia sp. on Mungbean (Vigna radiata)

There is growing interest in producing mungbean ( Vigna radiata L. Wilczek) in the United States, which is driven by increased consumer demand. Strategies are needed for United States farmers to take advantage of this high-value crop and its environmental sustainability. Recommendations for the management of mungbean seedling and root diseases are lacking. Preliminary research in central Iowa mungbean fields from 2019 to 2023 has shown that mungbean is particularly vulnerable to Fusarium virguliforme, the cause of soybean sudden death syndrome (SDS), and Rhizoctonia sp., the cause of damping-off, root decay, premature defoliation, and pod abortion. The purpose of this study was to screen a variety of fungicides as a seed treatment or a soil band application to control root rot in mungbean. We performed three field studies over 2 years using mungbean cultivars Berken and OK2000. Seed treatments Evergol Energy + fluopyram and Evergol Energy + pydiflumetofen showed the highest performance ( P &lt; 0.05), with approximately 30% more healthy roots than nontreated controls. Other treatments exhibited about 20% more healthy roots than the nontreated control. Biotam in-furrow application showed the highest plant population for ‘OK2000’, but we observed no treatment differences in plant stand for ‘Berken’.

Enhanced activity of Trichoderma asperellum introduced in solarized soil and its implications on the integrated control of strawberry-black root rot

An effective method for maintaining the activity and longevity of microorganisms in adverse conditions is microencapsulation. In the present study, synthetic alginate pellets were developed as carriers for the biocontrol agent Trichoderma asperellum. In two field experiments, solarization was applied for three weeks to loamy clay soil that was naturally infested with strawberry-black root rot fungi (Fusarium solani, Rhizoctonia solani and Machrophomina phaseolina). Following solarization, T. asperellum-based alginate pellets or spore suspension were added to the soil. Data reveal that, three weeks solarization of irrigated soil increased its maximum temperature reached by 11–14.2 °C (1–10 cm depth), 11.6–13.1 °C (11–20 cm depth) and 10.1–12.2 °C (21–30 cm depth). In either trial, solarization also successfully lowers the vitality of strawberry-black root rot fungi directly after the solarization phase. When compared to controls, strawberry-black root rot was substantially less common in solarized plots. In two field trials, soil solarization followed by inoculation with alginate pellets based on T. asperellum led to the greatest reductions in black root rot incidence (59.3 and 74.1 %) and severity (72.5 and 75.2 %), as compared to un-solarized control plots. In vivo studies, this treatment dramatically increased the activity of defensive enzymes (peroxidase and chitinase) and strawberry yield (60.5 and 60.0 %, respectively), as compared to non-solarized control plots. In two field studies, the rhizosphere population of native Trichoderma spp. Developed more in solarized soils after the application of alginate pellets based on T. asperellum (86.5 and 83.6 %, respectively), compared to the non-solarized control.

A Novel Plant-Derived Biopesticide Mitigates Fusarium Root Rot of Angelica sinensis by Modulating the Rhizosphere Microbiome and Root Metabolome.

Fusarium root rot caused by the Fusarium species complex significantly affects the yield and quality of Angelica sinensis, a valuable medicinal herb. Traditional management primarily relies on chemical fungicides, which have led to pathogen resistance, environmental hazards, and concerns regarding public health and the active components in A. sinensis. This study explores the efficacy of a novel plant-derived biopesticide Shi Chuang Zhi Feng Ning (T1; SCZFN), alongside Bacillus subtilis wettable powder (T2) and a chemical fungicide (T3), in controlling root rot and understanding their impacts on the rhizosphere microbial community and root metabolome. Results of the field experiment demonstrated that treatments T1 and T3 achieved control efficiencies of 73.17% and 75.45%, respectively, significantly outperforming T2 (39.99%) and the control. High-throughput sequencing revealed that all treatments altered the diversity and structure of microbial communities, with T1 and T2 reducing the abundance of taxa linked to root rot, such as Muribaculaceae spp., Humicola spp., Fusarium spp., and Mycochlamys spp. Treatment T1 notably enhanced beneficial bacterial taxa, including Acidobacteria spp., Nitrospira spp., and Pedosphaeraceae spp., involved in carbon cycling and plant growth promotion. Metabolomic analysis identified 39, 105, and 45 differentially expressed metabolites (DEMs) across the treatments, demonstrating T1's potential to modulate the root metabolome effectively. Further, a correlation analysis demonstrated a stronger correlation between distinct microorganisms with significant influence and DEMs of T1 treatment compared to other treatments. These findings underscore biopesticide SCZFN's role in enhancing plant health and disease suppression in A. sinensis, providing insights into its biocontrol mechanisms and supporting the development of sustainable disease management strategies in its cultivation.

Characterization of Fusarium solani Associated with Tobacco (Nicotiana tabacum) Root Rot in Henan, China.

The aim of this study was to characterize the Fusarium solani species complex (FSSC) population obtained from tobacco roots with root rot symptoms by morphological characteristics, molecular tests, and assessment of pathogenicity. Cultures isolated from roots were white to cream with sparse mycelium on potato dextrose agar, with colony growth of 21.5 ± 0.5 to 29.5 ± 0.5 mm after 3 days. Sporodochia were cream on carnation leaf agar (CLA) and Spezieller Nährstoffarmer agar (SNA), and macroconidia formed in sporodochia were 3 to 6 septate and straight to slightly curved, with wide central cells, a slightly short blunt apical cell, and a straight to almost cylindrical basal cell with a distinct foot shape, ranging in size from 20.92 to 64.37 × 3.91 to 6.57 μm. Microconidia formed on CLA were reniform and fusiform, with 0 or 1 to occasionally 2 septa, that formed on long monophialidic conidiogenous cells, with a size range of 5.99 to 32.32 × 1.76 to 5.84 μm. Globose to oval chlamydospores were smooth- to rough-walled, 6.5 to 13.3 ± 0.37 μm in diameter, and terminal or intercalary and occurred singly, in pairs, or occasionally in short chains on SNA. Molecular tests consisted of sequencing and phylogenetic analysis of the translation elongation factor-1 alpha (EF-1α), RNA polymerase II largest subunit, and second largest subunit regions. All the obtained sequences revealed 98.14 to 100% identity to F. solani in both Fusarium ID and Fusarium MLST databases. Phylogenetic trees of the EF-1α gene and concatenated three-locus data showed that isolates from tobacco in Henan grouped in the proposed group 5, which is nested within FSSC clade 3 (FSSC 5). Twenty-seven of the 28 isolates caused root rot in artificially inoculated tobacco seedlings, with a disease severity index ranging from 15.00 ± 1.67 to 91.11 ± 2.22. Cross-pathogenicity tests showed that three representative isolates were virulent to six species of Solanaceae and two species of Poaceae, with disease severity indexes ranging from 6.12 ± 0.56 to 84.44 ± 0.00, indicating that these isolates have a wide host range. The results may inform the control of tobacco root rot through improved crop rotations.

Effect of Bio Control Agents on Controlling Root Rot and Damping-off Disease of Cucumber Seedlings Caused by Rhizoctonia solani

Root rot and seedlings damping-off disease caused by Rhizoctonia solani is the most damaging disease of cucumber. This disease causes reducing yield in cucumber. This study conducted laboratory and greenhouse conditions to find out the efficacy of biological control agents, Trichoderma harzianum, Bacillus subtilis, the chemical compound Bion, and fungicide revanol. The results of pathogenicity test of R. solani on cucumber seeds showed that R. solanihas led to a significant reduction in the percentage of germination and seed rot compared to the control treatment, which amounted to 100%. The results showed the ability of all control agents used in this study to reduce the incidence of the disease. The Bion (benzothiadiazole) treatment showed significant effect and outperformed the other treatments in increasing the activity of the peroxidase enzyme, which was recorded at 14,440 (unit. minute-1.g wet weight-1). It also achieved the highest significant increase in total phenolics 1.52 (mg -1 . gram wet weight -1). Biological control agent T. harzianum has outperformed on other treatments in causing an increase in the activity of the polyphenol oxidase enzyme, it has recorded 1811.7 (unit. minute - 1 .gram of wet weight - 1 leaf).

Control of coptis root rot by combination of Bacillus cereus isolate Y9 and other antagonistic microorganisms

Root rot is a destructive soil-borne disease of Coptis chinensis, which depends on chemical control at present, and more attention should be paid to biocontrol of disease. In the present research, isolate Y9 isolated from healthy root samples of Coptis, was identified as Bacillus cereus. Further screening and pot experiments showed that B. cereus isolate Y9 inhibited the growth of the main causal agents of coptis root rot disease (Fusarium solani and F. avenaceum) and seven other phytopathogenic fungi. The application of B. cereus isolate Y9 and compatible Trichoderma harzianum, T. atroviride and B. amyloliquefaciens, singly and in combination were found to be effective against Fusarium root rot in vitro and in field experiments. In field experiments, combinations of T. harzianum + B. amyloliquefaciens + Y9 (HYJ, in ratio of 1:1:1) showed the highest control efficacy of 63.85%, which was higher than the expected value (53.18%), indicating synergistic effect on the control of coptis root rot. Therefore, B. cereus isolate Y9 may be a potential biological control agent, and combined use with T. harzianum and B. amyloquefaciens offered even greater potential. The long-term effects of isolate B. cereus Y9 and its combinations on C. chinensis should be assessed in different locations and seasons in the future.

Biocontrol potential of an artificial synthetic bacterial consortium against peony root rot disease

Tree peony (Paeonia suffruticosa), a traditional Chinese cultivated flowering shrub and a prominent landscaping plant, is subject to root rot. The key symptoms of root rot include black roots and the yellowing of leaves. Biological control is an effective and eco-friendly strategy for managing this disease. This study focused on the isolation, identification, and biological control of the pathogens causing peony root rot. Utilizing tissue isolation, pathogenicity determination, and rDNA-ITS sequence analysis, Fusarium solani and Fusarium oxysporum were determined to be the primary causal agents of peony root rot. Illumina MiSeq high-throughput sequencing of 16 s-rDNA was used to investigate and characterize bacterial community structure and diversity in healthy and diseased peony roots, rhizosphere, and bulk soil. Results indicated that the presence of pathogenic fungi influences the structure of the rhizosphere bacterial community and that peony roots exhibit a strong selective effect on root bacterial colonization. Variations in the composition of the endophytic microbial community in healthy and diseased roots exceeded the variation in the rhizosphere. Proteobacteria and Actinobacteria are the dominant taxa in the rhizosphere and among root endophytes, comprising 90–96 % of the bacterial microbiota. The rhizosphere of healthy plants exhibits a significant enrichment in Proteobacteria (79.6 %) and Actinobacteria (14.9 %), while root endophytes in healthy plats exhibit enrichment in Proteobacteria (83.5 %). In contrast, the rhizosphere and root endophytes in diseased plants are abundant in Proteobacteria (69 % and 66.1 %, respectively). Notably, nine strains of biocontrol bacteria were isolated. Three synthetic bacterial consortia were then constructed based on inhibitory assays and the dissolving rates of phosphorus and potassium exhibited by the candidate bacteria. The synthetic bacterial consortia were evaluated for biocontrol and growth promotion properties. The constructed synthetic consortium with the best performance reduced the average morbidity and mortality of treated plants by 27.59 % and 55.56 %, respectively, compared to the untreated control. In summary, synthetic bacterial consortium I (SCI) exhibited the best disease control and growth-promoting effects on tree peony. Using a synthetic bacterial consortium represents a new and novel approach to the biological control of peony root rot.

Bacillus velezensis B63 and chitosan control root rot, improve growth and alter the rhizosphere microbiome of geranium

The root rot complex of geranium plants caused by Rhizoctonia solani and Macrophomina phaseolina is a major threat, and control of these pathogens predominantly relies on chemicals. This study explored multifaceted applications of Bacillus velezensis (strain B63) and chitosan, assessing their biocontrol efficacy against root rot, and their subsequent effects on rhizosphere communities. Strain B63 was antagonistic to R. solani and M. phaseolina. Under field conditions, greatest efficacy was obtained with strain B63 (36% and 33% disease reductions in, respectively, two growing seasons), chitosan soaking + foliar spray 0.2% (CSF 0.2%) (33 and 27% reductions), and 0.1% chitosan soaking + foliar spray (CSF 0.1%) (33 and 26% reductions). These treatments also changed rhizosphere microbiota, as shown by numbers of colony-forming units (CFU) and 16S rRNA gene microbiome analyses. Concomitant with rhizosphere shifts, essential oil yields and composition were positively affected, as shown by gas chromatography analyses. Chitosan soaking + foliar spray 0.2% increased concentrations of citronellol (1.36-fold), geraniol (1.37-fold), citronellyl formate (1.54-fold), and geranyl formate (1.94-fold) in geranium essential oil, compared with the experimental controls. Strain B63 also increased these essential oils by 1.04- to 1.27-fold. B63 also enhanced eugenol levels by 1.35-fold. Treatments with B63 were more effective than chitosan in improving the geranium plant morphological parameters (plant height, numbers of branches, biomass). These results show that B. velezensis strain B63 treatments have potential for enhancing yields and product quality from geranium plant under root rot infection.

Bioassay-guided isolation of three new alkaloids from Suillus bovinus and preliminary mechanism against ginseng root rot.

In order to control the occurrence of ginseng root rot caused by Fusarium solani (Mart.) Sacc., the antifungal compounds of the mushroom Suillus bovinus were investigated. And three new alkaloids (1-3), named bovinalkaloid A-C, along with one known analog (4), were isolated and identified by bioassay-guided isolation and spectroscopic analyses. Compound 1 strongly inhibited the mycelial growth and spore germination of F. solani with minimum inhibitory concentration of 2.08 mM. Increases in electrical conductivity, nucleic acid, and protein contents, and decreases in lipid content showed that the membrane permeability and integrity were damaged by compound 1. Compound 1 also increased the contents of malondialdehyde and hydrogen peroxide and the activities of antioxidant enzymes, indicating that lipid peroxidation had taken place in F. solani. Compound 1 may serve as a natural alternative to synthetic fungicides for the control of ginseng root rot.

The novel Pseudomonas thivervalensis strain JI6 promotes growth and controls rusty root rot disease in Panax ginseng

The bacterial strain JI6, which has plant growth-promoting characteristics, was isolated from ginseng rhizosphere soil. It can produce indoleacetic acid (IAA), dissolve phosphorus, dissolve potassium and fix nitrogen and significantly promoted the growth of ginseng. The strain was identified as Pseudomonas thivervalensis by morphological, physiological and biochemical characteristics and 16S rDNA sequence analysis. The bud length of ginseng seeds treated with 109 CFU/mL JI6 suspension increased significantly by 42.76 % after 15 days. The fresh weight and the ginsenoside content of 3-year-old ginseng roots significantly increased by 38.72 % and 24.20 %, respectively with the 108 CFU/mL JI6 suspension for five months in the field. The strain JI6 can inhibit the six fungal pathogens and control rusty root rot of ginseng. For the biocontrol mechanism, the strain JI6 can colonize in ginseng rhizosphere soil. After treatment with JI6, the activitie of five ginseng defence enzymes of β-1.3 glucanase, peroxidase and phenylalanine ammonia-lyase, chitinase and superoxide dismutase and four soil enzymes of urease, phosphatase, invertase, and catalase significantly increased. The effect of strain JI6 on soil microbial community showed that the microbial diversity increased and the abundance of beneficial microorganisms elevated, while the abundance of pathogenic microorganisms decreased. This study indicate the great potential of P. thivervalensis JI6 for use as a biological agent for the control of ginseng rusty root rot.

Suppression of Root Rot Fungal Diseases in Common Beans (Phaseolus vulgaris L.) through the Application of Biologically Synthesized Silver Nanoparticles.

The biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a safe replacement for conventional chemical synthesis methods to fight plant pathogens. In this study, the antifungal activity of biosynthesized AgNPs was evaluated both in vitro and under greenhouse conditions against root rot fungi of common beans (Phaseolus vulgaris L.), including Macrophomina phaseolina, Pythium graminicola, Rhizoctonia solani, and Sclerotium rolfsii. Among the eleven biosynthesized AgNPs, those synthesized using Alhagi graecorum plant extract displayed the highest efficacy in suppressing those fungi. The findings showed that using AgNPs made with A. graecorum at a concentration of 100 μg/mL greatly slowed down the growth of mycelium for R. solani, P. graminicola, S. rolfsii, and M. phaseolina by 92.60%, 94.44%, 75.93%, and 79.63%, respectively. Additionally, the minimum inhibitory concentration (75 μg/mL) of AgNPs synthesized by A. graecorum was very effective against all of these fungi, lowering the pre-emergence damping-off, post-emergence damping-off, and disease percent and severity in vitro and greenhouse conditions. Additionally, the treatment with AgNPs led to increased root length, shoot length, fresh weight, dry weight, and vigor index of bean seedlings compared to the control group. The synthesis of nanoparticles using A. graecorum was confirmed using various physicochemical techniques, including UV spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. Collectively, the findings of this study highlight the potential of AgNPs as an effective and environmentally sustainable approach for controlling root rot fungi in beans.

Combined interaction between the diazotrophic Niallia circulans strain YRNF1 and arbuscular mycorrhizal fungi in promoting growth of eggplant and mitigating root rot stress caused by Rhizoctonia solani

Rhizoctonia root rot of eggplant, caused by Rhizoctonia solani, is an economically important disease. Niallia circulans YRNF1 and arbuscular mycorrhizal fungi (AMF) were assessed for their biocontrol and biofertilizing effects against R. solani, as potential replacements for synthetic fungicides and fertilizers. The diazotrophic N. circulans YRNF1, isolated from soil, reduced in vitro growth of R. solani by 42%. GC-MS analysis of culture filtrate of N. circulans YRNF1 detected bioactive compounds, including butyric acid (85%) and ethylene glycol (8%). In greenhouse experiments, combined application of N. circulans YRNF1 and AMF reduced the severity of eggplant root rot by 26%. This combined treatment triggered the transcriptional expression of five resistance genes (JERF3, PAL1, C3H, CHI2, and HQT) in the treated eggplants. Biochemical analyses of the infected eggplant roots treated with the combined bio-inoculants showed enhancement of the phenol content (+188%), and increased antioxidant enzyme activity, mainly of POD (+104%) and PPO (+72%). Combined application of N. circulans YRNF1 and AMF also promoted eggplant growth and improved the total NPK concentrations in treated plant leaves. Inoculation of eggplant with N. circulans YRNF1 in the presence of AMR increased the mycorrhization level. This is the first report of N. circulans and AMF as potential agents for biological control of Rhizoctonia root rot and growth promotion of eggplant.

Rhizospheric microbiota of suppressive soil protect plants against Fusarium solani infection.

Fusarium infection has caused huge economic losses in many crops. The study aimed to compare the microbial community of suppressive and conducive soils and relate to the reduction of Fusarium wilt. High-throughput sequencing and microbial network analysis were used to investigate the differences in the rhizosphere microbiota of the suppressive and conducive soils and to identify the beneficial keystone taxa. Plant pathogens were enriched in the conducive soil. Potential plant-beneficial microorganisms and antagonistic microorganisms were enriched in the suppressive soil. More positive interactions and keystone taxa existed in the suppressive soil network. Thirty-nine and 16 keystone taxa were identified in the suppressive and conducive soil networks, respectively. Sixteen fungal strains and 168 bacterial strains were isolated from suppressive soil, some of which exhibited plant growth-promotion traits. Thirty-nine bacterial strains and 10 fungal strains showed antagonistic activity against F. solani. Keystone taxa Bacillus and Trichoderma exhibited high antifungal activity. Lipopeptides produced by Bacillus sp. RB150 and chitinase from Trichoderma spp. inhibited the growth of F. solani. Microbial consortium I (Bacillus sp. RB150, Pseudomonas sp. RB70 and Trichoderma asperellum RF10) and II (Bacillus sp. RB196, Bacillus sp. RB150 and T. asperellum RF10) effectively controlled root rot disease, the spore number of F. solani was reduced by 94.2% and 83.3%. Rhizospheric microbiota of suppressive soil protects plants against F. solani infection. Antagonistic microorganisms in suppressive soil inhibit pathogen growth and infection. Microbial consortia consisted of keystone taxa well control root rot disease. These findings help control Fusarium wilt. © 2024 Society of Chemical Industry.