Promote Plant Health Research Articles

Protorhabditis nematodes and pathogen-antagonistic bacteria interactively promote plant health

BackgroundFertilization practices control bacterial wilt-causing Ralstonia solanacearum by shaping the soil microbiome. This microbiome is the start of food webs, in which nematodes act as major microbiome predators. However, the multitrophic links between nematodes and the performance of R. solanacearum and plant health, and how these links are affected by fertilization practices, remain unknown.ResultsHere, we performed a field experiment under no-, chemical-, and bio-organic-fertilization regimes to investigate the potential role of nematodes in suppressing tomato bacterial wilt. We found that bio-organic fertilizers changed nematode community composition and increased abundances of bacterivorous nematodes (e.g., Protorhabditis spp.). We also observed that pathogen-antagonistic bacteria, such as Bacillus spp., positively correlated with abundances of bacterivorous nematodes. In subsequent laboratory and greenhouse experiments, we demonstrated that bacterivorous nematodes preferentially preyed on non-pathogen-antagonistic bacteria over Bacillus. These changes increased the performance of pathogen-antagonistic bacteria that subsequently suppressed R. solanacearum.ConclusionsOverall, bacterivorous nematodes can reduce the abundance of plant pathogens, which might provide a novel protection strategy to promote plant health.6HVRaGfzCN9g8_uHWKg5j1Video

Invisible Allies: The Role of Endophytic Entomopathogenic Microbes in Insect Pest Control

Endophytic entomopathogenic microbes, including both bacteria and fungi, hold significant promise as biocontrol agents in sustainable pest management. While the biocontrol potential of entomopathogens are well-established, their role as mutualistic endophytes within plant tissues offers a relatively new avenue for enhancing pest suppression. The ability of these microbes to colonize plant tissues allows them to serve as internal defense agents against insect pests, while simultaneously promoting plant health and resilience to environmental stressors. Here, we explore the growing body of knowledge surrounding the use of endophytic entomopathogenic bacteria and fungi in pest management. These microbes contribute to pest control through direct effects on insect populations, such as mortality and feeding inhibition, as well as indirect plant-mediated mechanisms that enhance plant defenses. Additionally, endophytic entomopathogens provide a range of benefits to their plant hosts, including growth promotion, nutrient acquisition, and protection against pathogens. Despite the clear advantages of using endophytic entomopathogens, there remain key challenges to their widespread implementation. Environmental factors can influence their persistence and efficacy in the field, and their relatively slow mode of action compared to chemical pesticides presents a hurdle for rapid adoption in commercial agriculture. Non-target effects and the development of effective formulations to ensure consistent colonization are also areas that require further investigation. Addressing these challenges through continued research into the complex interactions between endophytes, insects, plants, and their environments will be essential for advancing the integration of endophytic entomopathogenic microbes into sustainable pest management systems.

Management of soft rot in pakchoi (Brassica chinensis L.) using polyphenols from pineapple peel waste

Soft rot is one of the most susceptible soil-borne diseases of pakchoi (Brassica chinensis L.), severely hindering its industrial development. The research aimed to evaluate the application effect of polyphenols extracted from pineapple peel waste in improving the rhizosphere soil environment of pakchoi infected by soft rot and promoting plant health and growth. We found that using pineapple peel polyphenols (PPPs) at 4 mg/mL concentration (P1 treatment) significantly improved soil quality, reduced pakchoi disease incidence, and effectively promoted pakchoi growth. Compared with the control group (CK), the P1 treatment led to a marked 79.97 % reduction in diseased pakchoi leaves. Meanwhile, the rhizosphere soil structure showed reduced diseased genera and increased beneficial bacterial phyla, along with boosted soil enzyme activities. Furthermore, P1 treatment improved key growth parameters of pakchoi, including neck thickness (62.07 %), plant height (57.43 %), fresh weight (154.52 %), dry weight (121.88 %), maximum leaf length (47.28 %), width (30.98 %), and total chlorophyll content (50.11 %). The application of PPPs has shown significant effects in enhancing the ecological environment of the diseased soil and reducing the incidence of soft rot disease of pakchoi and has great potential in increasing the yield of pakchoi. This study offers an eco-friendly and sustainable approach for the valorization of PPPs and the management of soil-borne diseases, which holds profound implications for enhancing crop quality, soil health, and human well-being.

Enhancing the efficiency of phytoremediation using water hyacinth (Eichhornia crassipes) for 2,4-dichlorophenoxyacetic acid removal with modified biochar as an assisted agent

This study explores an innovative integrated system for removing the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from aquatic environments, utilizing a combination by modified biochar derived from waste biomass of palm kernel shells (PKS-BM) and water hyacinth (Eichhornia crassipes). The characterization of the biochar revealed significant surface functional groups, a substantial surface area, and a mesoporous structure conducive to adsorption application. Biochar-assisted phytoremediation demonstrated markedly higher removal efficiencies of 2,4-D as compared to phytoremediation alone, achieving up to 98.7%, 96.9%, and 90.3% removal efficiency for 2,4-D concentrations of 50 mg/L, 100 mg/L, and 150 mg/L, respectively. Additionally, the presence of biochar significantly enhanced the morphological growth of Eichhornia crassipes, particularly under higher concentrations of 2,4-D, by mitigating toxic effects and supporting healthier plant development. These findings suggest that integrating biochar into phytoremediation system offers a promising, sustainable approach for effectively removing herbicides from contaminated water bodies while also promoting plant health and growth.

Symbiotic conserved arbuscular mycorrhiza fungi supports plant health

Arbuscular mycorrhiza fungi (AMF) forms a multi-beneficial symbiotic relationship with the host plant, therefore it is considered to be an effective helper to promote plant health. However, failure to consider the source or universality of AMF is often unstable during application. Therefore, it is necessary to screen potential AMF inoculants based on the source and the relationship with host. In search of more effective and broad-spectrum AMF inoculants, we studied AMF community structure properties of healthy and diseased plants in 24 fields from four sampling sites. The results indicated that the environmental filtering effect of roots was obvious, which was manifested as a decrease of α-diversity from rhizosphere to root. Differences in α-diversity between healthy and diseased roots further indicate the importance of AMF communities within roots for maintaining plant health. Glomus is significantly enriched and dominant in healthy roots, independent of environment and phylogenically conserved. Spores were further isolated and evaluated for their disease-preventing and pro-growth properties. Based on whether they were symbiotic with plant and root-enrichment characteristics, isolated AMF spores were classified as symbiotic conserved, symbiotic non-conserved, and non-symbiotic AMF. After spores were propagated and inoculated to plant roots, only symbiotic conserved AMF significantly promoted plant growth and maintained health, highlighting the potential of symbiotic conserved AMF in sustainable plant production.

Antibiotic-producing plant-associated bacteria, anti-virulence therapy and microbiome engineering: Integrated approaches in sustainable agriculture.

Plant health is crucial for maintaining the well-being of humans, animals and the environment. Plant pathogens pose significant challenges to agricultural production, global food security and ecosystem biodiversity. This problem is exacerbated by the impact of climate change, which is expected to alter the emergence and evolution of plant pathogens and their interaction with their plant hosts. Traditional approaches to managing phytopathogens involved the use of chemical pesticides, but alternative strategies are needed to address their ongoing decline in performance as well as their negative impact on the environment and public health. Here, we highlight the advancement and effectiveness of biocontrol strategies based on the use of antimicrobial-producing plant-associated bacteria, anti-virulence therapy (e.g. quorum quenching) and microbiome engineering as sustainable biotechnological approaches to promote plant health and foster sustainable agriculture. Notably, Enterobacterales are emerging as important biocontrol agents and as a source of new antimicrobials for potential agricultural use. We analysed here the genomes of over 250 plant-associated enterobacteria to examine their potential to synthesize secondary metabolites. Exploration of the plant microbiome is of major interest in the search for eco-friendly alternatives for reducing the use of chemical pesticides.

HONEY PUMPKIN STEM BORER, Apomecyna saltator FABRICIUS (COLEOPTERA: CERAMBYCIDAE) CAN BE CONTROLLED WITH PHOSPHORUS AND POTASSIUM FERTILIZER

Apomecyna saltator, a notorious pest of honey pumpkin plants, poses a significant threat to both vegetative and generative phases, leading to considerable production losses. Despite its agricultural impact, there are limited studies on effective management strategies for this pest. This research investigates the effect of combined phosphorus and potassium fertilization on controlling A. saltator infestations in honey pumpkin plants. The study was conducted at the Teaching and Research Farm of the Faculty of Agriculture, Jambi University. A randomized block design with five treatments and five replications was used, testing different combinations of SP-36 phosphorus and potassium chloride (KCl) fertilizers: no fertilization (p0), SP-36 0.67 g/plant + KCl 1.25 g/plant (p1), SP-36 1.00 g/plant + KCl 1.88 g/plant (p2), SP-36 1.34 g/plant + KCl 2.51 g/plant (p3), and SP-36 1.67 g/plant + KCl 3.13 g/plant (p4). The variables observed included stem diameter, larval population, percentage of plant damage, number of attacked plant segments, fruit weight, and overall production. Data were analyzed using ANOVA and Duncan's Multiple Range Test (DMRT). The results indicated that combining phosphorus and potassium fertilizers significantly increased stem diameter, fruit weight, and yield while reducing larval populations, plant damage, and affected segments. The study demonstrates that phosphorus and potassium strengthen honey pumpkin plants and negatively impact A. saltator infestations. This research highlights a novel approach to pest control, showing that targeted fertilization promotes plant health and suppresses the honey pumpkin stem borer (A. saltator). This dual benefit of nutrient application provides a sustainable and efficient pest management strategy, offering a fresh perspective on integrated crop protection.

Phytobiomes: Harnessing the Power of Microbial Communities for Plant Health

Phytobiomes encompass the dynamic ecosystems surrounding plants, which include a diverse range of microbial communities such as fungi, bacteria, algae, viruses, and nematodes. These microorganisms interact intricately with plants, influencing their health, growth, and resilience. Beneficial fungi form symbiotic relationships with plant roots, enhancing nutrient absorption, while bacteria play a role in nitrogen fixation and disease suppression. Algae contribute to soil health and organic matter decomposition, and viruses, though often seen as harmful, can provide resistance to certain pathogens. Nematodes, both beneficial and parasitic, regulate soil nutrient cycles and influence plant growth. Harnessing the potential of these microbial communities offers promising solutions for sustainable agriculture. By promoting beneficial interactions within the phytobiome, it is possible to improve plant productivity, enhance nutrient use efficiency, and increase tolerance to environmental stresses such as drought, salinity, and pathogens. Phytobiome research aims to uncover the complex relationships within these microbial networks to develop novel agricultural practices that reduce reliance on chemical inputs. This holistic approach not only promotes plant health but also ensures ecological balance, contributing to the long-term sustainability of agroecosystems in the face of environmental challenges. Understanding the power of microbial communities within phytobiomes is key to advancing future agricultural innovations.

Microbial interactions modify saffron traits selectively and modulate immunity through adaptive antioxidative strategy: Organic cultivation modules should be trait and crop-specific

Saffron (Crocus sativus L.) is a high-value, low-volume niche cash crop that has the unique ability to synthesize apocarotenoids. Since different biofertilizers are advocated for promoting plant health, we aimed to evaluate the interactions of commercially available microbial inoculants with this unique hysteranthous plant species. We studied the interactive effect of microbial inoculants on agronomical, physiological and biochemical aspects of Crocus growth, corm multiplication and apo-carotenoid biosynthesis. Significant differences in nutrient mobilization potential, induced systemic resistance, plant growth, corm, and stigma yield/quality were detected between the different biofertilizer combinations. The arbuscular mycorrhizal fungi (AMF) + phosphate-solubilizing bacteria (PSB) + potassium-solubilizing bacteria (KSB) combination was the most suitable for enhancing shoot biomass, root depth, and root biomass. Additionally, the average number of flowers per corm, stigma yield, and corm yield were greatest for the same combination. The highest multiplication rate of mother corms and a small corm index were recorded for plants inoculated with Azospirillum + PSB + KSB. Although Azospirillum caused maximum multiplication, the percentage of smaller daughter corms was greater, while the replacement of Azospirillum with AMF resulted in maximum percentage of larger corms. Plant health improved through AMF-mediated microbial interactions, which induced systemic resistance via enzymatic and nonenzymatic mechanisms and increased the uptake of P, K, Cu, Fe, Mn, and Zn. The interrelationship between plant and microbial consortium was complex, causing trait-specific qualitative and quantitative impacts on saffron attributes. Microbial inoculants increased nutrient uptake by saffron plants and triggered biochemical defence response by causing mild stress, making the plant more growth-responsive and better equipped for defence. Microbial interaction increased saffron yield and quality by favourably modulating plant metabolism, majorly overlapping with plant protection mechanisms. However, plant-microbial combinations in an organic production module are trait-specific and should be chosen carefully.

Biochar alters maize growth, mycorrhizal associations and fall armyworm performance

Abstract Background and aims Biochar is a carbon source employed to improve soil properties, promoting plant health and nutrition in agroecosystems. Root associated microorganisms such as arbuscular mycorrhizal fungi (AMF) are also used as bioinoculants in combination with biochar to provide eco-friendly alternatives for crop production under unfavorable growth conditions. However, information on the effects of biochar on multitrophic interactions of plants with herbivorous insects is limited. Therefore, the objective of this work was to evaluate the effect of biochar and arbuscular mycorrhizae on plants and herbivorous insects. Methods We established a multifactorial experiment with maize plants, AMF (two strains, Rizhophagus irregularis and a native consortium) and the Fall Armyworm Spodoptera frugiperda with and without soil application of biochar. Variables of biomass, plant nutrition, mycorrhizal colonization and performance of herbivorous insects were measured. Results We found that biochar reduced insect herbivory and promoted mycorrhizal association in maize. However, plant growth was reduced. Additionally, AMF increased the weight of fall armyworm larvae. Conclusion Our results show that biochar influences maize plant development, AMF, and fall armyworm performance, but did not affect interactions between these below- and above ground components.

New Detection Methods for Cryphonectria Hypovirus 1 (CHV1) through SYBR Green-Based Real-Time PCR and Loop-Mediated Isothermal Amplification (LAMP).

Some mycoviruses can be considered as effective biocontrol agents, mitigating the impact of phytopathogenic fungi and consequently reducing disease outbreaks while promoting plant health. Cryphonectria parasitica, the causal agent of chestnut blight and a highly destructive pathogen, experienced a notable decrease in its virulence with the identification of cryphonectria hypovirus 1 (CHV1), a naturally occurring biocontrol agent. In this study, two innovative diagnostic protocols designed for the accurate and efficient detection of CHV1 are introduced. The ORF A and ORF B regions of CHV1 are targeted by these techniques, which employ colorimetric loop-mediated isothermal amplification (LAMP) with 2 Colorimetric LAMP Master Mix and real-time quantitative PCR (qPCR) with SYBR Green chemistry, respectively. The LAMP assay presents a discernible color transition, changing from pink to yellow after a 35 min incubation period. Comparative analysis, when assessed against two established reverse transcription-PCR (RT-PCR) techniques, reveals a significant enhancement in sensitivity for both the LAMP approach, which offers a tenfold increase, and the qPCR method, which showcases a remarkable 100-fold sensitivity improvement. Throughout the comparison phase, it was evident that the RT-PCR, LAMP, and qPCR procedures displayed superior performance compared to the Bavendamm test, relying on phenol oxidase activity, effectively distinguishing hypovirulent strains. Consequently, this study introduces two pioneer diagnostic assays for highly sensitive CHV1 detection, representing a substantial advancement in the realm of CHV1 surveillance techniques. These methodologies hold significant promise for enhancing research endeavors in the domain of the biological control of C. parasitica.

Multispectral, Thermographic and Spectroradiometric Analyses Unravel Bio-Stimulatory Effects of Wood Distillate in Field-Grown Chickpea (Cicer arietinum L.)

Wood distillate (WD) has recently emerged as a promising bio-stimulant for sustainable legume crop production, owing to its ability to enhance seed yield and quality. However, no studies exist on the effects of WD on chickpea plants at pre-harvesting stages, hindering the farmers’ ability to acquire valuable knowledge on the early action of WD on the plants’ status and preventing the establishment of proactive measures to optimize WD use in agriculture. In this study, two multispectral, thermographic and spectroradiometric surveys, along with in-situ measurements of specific plant biometric traits, were conducted across the reproductive stage of field-grown chickpea in order to evaluate the early involvement of WD on plant health. The acquired multispectral images were used to calculate the Normalized Difference Vegetation Index (NDVI), revealing a notable ~35% increase in NDVI scores of WD-treated plants at the onset of physiological maturity, and indicating an improved plant status compared to the control (water-treated) plants. Moreover, control and WD-treated plants exhibited distinct spectral signatures across the visible, near-infrared (NIR) and short-wave infrared (SWIR) spectra, suggesting potential changes in their photosynthetic capacity, structural properties and water content both at the leaf and at the pod level. Furthermore, WD-treated plants showed a 25% increase in pod production, particularly at the beginning of seed maturity, suggesting that enhancements in plant status were also reflected in higher pod yields. These results point to a beneficial effect of WD on plant health during the preliminary stages of seed formation and indicate that a combination of both multispectral and spectroradiometric analyses can provide critical insights on the status of chickpea crops at pre-harvesting stages. In addition, these findings emphasize the importance of analyzing pre-harvesting stages to gain insights into the early involvement of WD in promoting plant health and, ultimately, in predicting final crop yields.

One stone two birds: Endophytes alleviating trace elements accumulation and suppressing soilborne pathogen by stimulating plant growth, photosynthetic potential and defense related gene expression

In the present investigation, we utilized zinc nanoparticles (Zn-NPs) and bacterial endophytes to address the dual challenge of heavy metal (HM) toxicity in soil and Rhizoctonia solani causing root rot disease of tomato. The biocontrol potential of Bacillus subtilis and Bacillus amyloliquefaciens was harnessed, resulting in profound inhibition of R. solani mycelial growth and efficient detoxification of HM through strong production of various hydrolytic enzymes and metabolites. Surprisingly, Zn-NPs exhibited notable efficacy in suppressing mycelial growth and enhancing the seed germination (%) while Gas chromatography-mass spectrometry (GC-MS) analysis unveiled key volatile compounds (VOCs) crucial for the inhibition of pathogen. Greenhouse trials underscored significant reduction in the disease severity (%) and augmented biomass in biocontrol-mediated plants by improving photosynthesis-related attributes. Interestingly, Zn-NPs and biocontrol treatments enhanced the antioxidant enzymes and mitigate oxidative stress indicator by increasing H2O2 concentration. Field experiments corroborated these findings, with biocontrol-treated plants, particularly those receiving consortia-mediated treatments, displayed significant reduction in disease severity (%) and enhanced the fruit yield under field conditions. Root analysis confirmed the effective detoxification of HM, highlighting the eco-friendly potential of these endophytes and Zn-NPs as fungicide alternative for sustainable production that foster soil structure, biodiversity and promote plant health.

Green Microbe Profile: Rhizophagus intraradices—A Review of Benevolent Fungi Promoting Plant Health and Sustainability

Arbuscular mycorrhizal fungi (AMF) such as Rhizophagus intraradices (formerly known as Glomus intraradices) are of great importance to maintaining the soil ecosystem while supporting sustainable agriculture and practices. This review explores the taxonomy of Rhizophagus intraradices, their attributes, mycorrhizal symbiosis, plant growth improvement, nutrient recycling in the soil, soil health and environmental rehabilitation, and challenges that impede the effective use of AMF in agriculture. AMF impacts soil structure by releasing organic compounds like glomalin, improving total organic carbon and water-holding capacity, and reducing water scarcity. AMF, in sustainable agriculture, not only improves crop productivity through nutrient uptake but also enhances soil fertility and plants’ resistance to so-called stress from abiotic factors as well. The integration of AMF with other beneficial microorganisms in organic farming will be powerful both to ensure long-term soil output and to protect food from bacteria. Nevertheless, chemical inputs and spatial biases of the researchers remain matters to be solved in connection with the broad feasibility of AMF use.

Biocontrol agent amendments shape the soybean rhizosphere in a cyst nematode (Heterodera glycines) conducive soil over a two-year field trial

Plant-associated beneficial microorganisms play a vital role in promoting plant health, fitness, and disease suppression, leading to improved plant growth and protection against specific plant parasites. Microbial amendments may reduce nematode parasite populations and ensure plant yield, yet their long-term impact on the native plant microbiome under field conditions is not well understood. In this study, we evaluated the effectiveness of biocontrol products against soybean cyst nematode (SCN) using two application methods over a two-year period under field conditions. Pochonia chlamydosporia PC10 (Rizotec), Bacillus methylotrophicus UFPEDA 20 (Onix), and Trichoderma koningiopsis GF 362 were applied either through seed inoculation or in-furrow treatment at planting. The treatments effectively reduced the nematode population, with T. koningiopsis showing significant deviations from the control and leading to a notable increase in yield. No difference in the Shannon diversity index was detected for the alpha-diversity of root-associated 16S, ITS2, and 18S communities. The dominant phyla were Proteobacteria, Acidobacteria, Actinobacteria for 16S; Ascomycota, Basidiomycota, Mortierellomycota for ITS2; and Ascomycota, and Cercozoa for 18S. In the 16S community, T. koningiopsis and B. methylotrophicus caused a 25 % increase in the relative abundance of Sphingomonas spp. compared to the control. Additionally, the relative abundance of Mortierella spp. significantly increased by 50 % in both the T. koningiopsis and B. methylotrophicus treatments compared to the control. Both treatments also led to a significant reduction in Fusarium spp. by 37.5 % and 31.5 %, respectively. Co-occurrence network analysis revealed that communities were disrupted after the first application, but grew more intricate and cohesive after the second year of biocontrol product amendment. T. koningiopsis and B. methylotrophicus demonstrated potential in reducing nematode and Fusarium populations, leading to increased yield production. However, under high nematode pressure, relying solely on biocontrol measures does not guarantee a reduction in SCN population or yield improvement. Manipulating the microbial community to reduce harmful organisms and promote biocontrol-related species may offer long-term benefits.

A history of strategies and a tapestry of triumphant tales in tackling plant fungal diseases

AbstractEver since the first crops were domesticated over 10,000 years ago, pests and pathogens have wreaked havoc on crop production. Despite diverse threats from longstanding and emerging diseases, plants continue to play a central role in meeting humanity's requirements for calories and nutrients. In this review, we discuss historical advances made by plant pathologists and breeders that have helped keep many plant diseases at bay. We focus predominantly on fungal diseases of five food crops—rice, wheat, maize, soybean and potato—that provide the bulk of calories consumed globally. We cover such historical triumphs in plant pathology as (i) advanced knowledge of fungal biology revolutionizing disease management strategies, (ii) integration of genetics by the ‘wheat wizard’ Rowland Biffen and others transforming the landscape of resistance breeding and (iii) the advent of modern fungicides—from a sinking ship in the 1660s—leading to dramatic yield enhancements. We also discuss (iv) the potential for emerging biocontrol agents to holistically promote plant health and yield. Today, the high homogeneity of crops in modern agricultural systems exacerbates yield losses due to disease by increasing pest/pathogen transmission rates and eroding natural spatial barriers to pest/pathogen dispersal. Meanwhile, climate change is altering the compositions of global pest and pathogen populations and expanding pest/pathogen territories with unpredictable consequences. As we look to the future, the strength of the plant pathology community remains central to developing innovative solutions to tackle these complex and expanding threats to plant health and secure a plentiful food supply.

Role of rhizospheric microbial enzymes in plant growth promotion, antagonism, and sustainable agriculture: A review

Plant growth-promoting rhizobacteria (PGPR) offer eco-friendly alternatives to chemical fertilizers, promoting sustainable agriculture by enhancing soil fertility, reducing pathogens, and aiding in stress resistance. In agriculture, they play a crucial role in plant growth promotion through the production of agroactive compounds and extracellular enzymes to promote plant health and protection against phytopathogens. In the rhizosphere, diverse microbial interactions, including those with bacteria and fungi, influence plant health by production of antimicrobial compounds. The antagonism displayed by rhizobacteria plays a crucial role in shaping microbial communities and has potential applications in developing a natural and environmentally friendly approach to pest control. The rhizospheric microbes showcase their ecological importance and potential for biotechnological applications in the context of plant-microbe interactions. The extracellular enzymes produced by rhizospheric microbes like amylases, chitinases, glucanases, cellulases, proteases, and ACC deaminase contribute to plant processes and stress response emphasizing their importance in sustainable agriculture. Moreover, this review highlights the new paradigm including artificial intelligence (AI) in sustainable horticulture and agriculture as a harmonious interaction between ecological networks for promoting soil health and microbial diversity that leads to a more robust and self-regulating agricultural system for protecting the environment in the future. Overall, this review emphasizes microbial interactions and the role of rhizospheric microbial extracellular enzymes which is crucial for developing eco-friendly approaches to enhance crop production and soil health.

Phytoremediation of Arsenic (As) in rice plants, mediated by Bacillus subtilis strain IU31 through antioxidant responses and phytohormones synthesis

Bacteria-assisted phytoremediation uses bacteria to promote plant health and improve its ability to remediate toxic heavy metals like Arsenic (As). Here, we isolated rhizobacteria and identified them as Bacillus subtilis strain IU31 using 16S rDNA sequencing. IU31 showed phosphate solubilization potential on Pikovskaya agar medium and produced siderophores, which were detected on Chromium Azurol-S (CAS) agar medium. Indole-3-acetic acid (IAA) and gibberellins (GAs), namely GA1, GA3, GA4, GA7, GA9, GA12, GA15, and GA24, were quantified by GC/MS-SIM analysis. The expression levels of genes involved in GA and IAA biosynthesis, such as cyp112, cyp114, trpA, and trpB, were assessed using semi-quantitative RT-PCR. Plant bioassays showed that As at a 15 mg/kg concentration reduced plant growth, chlorophyll content, and biomass. However, IU31 inoculation significantly improved plant growth dynamics, enhancing As accumulation by up to 50% compared with uninoculated plants. IU31 inoculation induced the bioconcentration factor (BCF) and bioaccumulation factor (BAF) of As in plants compared to uninoculated plants, but the translocation factor (TF) of As was unaffected by IU31 inoculation. IU31 inoculation effectively restored glutathione-S-transferase (GST) and catalase (CAT) enzyme activities, as well as glutathione (GSH) and hydrogen peroxide concentrations to nearly normal levels, which were significantly elevated in plants exposed to As stress. These results show that IU31 improves plant health and growth by producing IAA and GAs, which might contribute to the uptake and detoxification of As.

Preliminary Results of the Impact of Beneficial Soil Microorganisms on Okra Plants and Their Polyphenol Components

Okra (Abelmoschus esculentus L.) is a highly nutritious vegetable rich in vitamins, minerals, and bioactive compounds, including polyphenols, offering numerous health benefits. Despite its nutritional value, okra remains underutilized in Europe; however, its cultivation and popularity may rise in the future with increasing awareness of its advantages. In agricultural practices, beneficial soil microorganisms, such as arbuscular mycorrhizal fungi (AMF), Trichoderma spp., Streptomyces spp., and Aureobasidium spp., play crucial roles in promoting plant health, enhancing agricultural productivity together with improved crop nutritional value. This study aimed to investigate the effects of individual and combined inoculation on the polyphenol content of okra fruits, as analyzed by HPLC. Moreover, growth parameters and glutathione-S-transferase enzyme (GST) activities of okra leaves were also estimated. Tested microorganisms significantly increased the yield of okra plants except for A. pullulans strain DSM 14950 applied individually. All microorganisms led to increased GST enzyme activity of leaves, suggesting a general response to biotic impacts, with individual inoculation showing higher enzyme activity globally compared to combined treatments. According to the polyphenol compound analysis, the application of tested microorganisms held various but generally positive effects on it. Only the combined treatment of F. mosseae and Streptomyces strain K61 significantly increased the coumaric acid content, and the application of Aureobasidium strain DSM 14950 had a positive influence on the levels of quercetin and quercetin-3-diglucoside. Our preliminary results show how distinct polyphenolic compound contents can be selectively altered via precise inoculation with different beneficial microorganisms.

Biocontrol agents modulate phyllosphere microbiota interactions against pathogen Pseudomonas syringae

The pathogen Pseudomonas syringae, responsible for a variety of diseases, poses a considerable threat to global crop yields. Emerging biocontrol strategies employ antagonistic microorganisms, utilizing phyllosphere microecology and systemic resistance to combat this disease. However, the interactions between phyllosphere microbial dynamics and the activation of the plant defense system remain poorly understood. Here we show significant alterations in phyllosphere microbiota structure and plant gene expression following the application of biocontrol agents. We reveal enhanced collaboration and integration of Sphingomonas and Methylobacterium within the microbial co-occurrence network. Notably, Sphingomonas inhibits P. syringae by disrupting pathogen chemotaxis and virulence. Additionally, both Sphingomonas and Methylobacterium activate plant defenses by upregulating pathogenesis-related gene expression through abscisic acid, ethylene, jasmonate acid, and salicylic acid signaling pathways. Our results highlighted that biocontrol agents promote plant health, from reconstructing beneficial microbial consortia to enhancing plant immunity. The findings enrich our comprehension of the synergistic interplays between phyllosphere microbiota and plant immunity, offering potential enhancements in biocontrol efficacy for crop protection.