Plant Microbe Research Articles

Prevalence and underlying mechanisms of phylosymbiosis in land plants

Abstract Phylosymbiosis, the congruence of microbiome composition with host phylogeny, is a valuable framework for investigating plant–microbe associations and their evolutionary ecology. This review assesses the prevalence of phylosymbiosis across the plant kingdom, elucidates the fundamental ecological and evolutionary processes contributing to its occurrence based on previous research and explores commonly used methods for identifying phylosymbiosis. We find that the presence of phylosymbiosis may be influenced by both phylogenetic distance and the taxonomic level at which host plants are examined, with the strength of associations potentially decreasing as the taxonomic scale becomes finer. Notably, the endophytic microbiome exhibits a stronger phylosymbiosis signal compared with the epiphytic or rhizosphere-associated microbiomes. Microorganisms such as fungi and bacteria can yield highly variable evidence for phylosymbiosis due to differences in colonization, transmission or functional characteristics. We also outline how the four community assembly processes (dispersal, selection, diversification and drift) contribute to the establishment and maintenance of host–microbe phylosymbiosis. Furthermore, we highlight the diversity of methods employed to detect phylosymbiosis, which involves three key processes: constructing host phylogenies, assessing microbial data and statistically evaluating the correlation between host phylogeny and microbial composition. Remarkably different methodologies across studies make comparisons between findings challenging. To advance our understanding, future research is expected to explore phylosymbiosis at lower taxonomic levels and investigate different microbial communities coexisting synergistically within the same host. Understanding the relative importance of community assembly processes in driving phylosymbiosis will be critical for gaining deeper insights into the ecology and evolution of host–microbe interactions.

Harnessing Green Helpers: Nitrogen-Fixing Bacteria and Other Beneficial Microorganisms in Plant–Microbe Interactions for Sustainable Agriculture

The health of soil is paramount for sustaining life, as it hosts diverse communities of microorganisms that interact with plants, influencing their growth, health, and resilience. Beneficial microorganisms, including fungi and bacteria, form symbiotic relationships with plants, providing essential nutrients, promoting growth, and enhancing stress tolerance. These microorganisms, such as mycorrhizal fungi and plant growth-promoting bacteria, play crucial roles in nutrient cycling, soil health, and plant productivity. Additionally, they help lessen reliance on chemical fertilizers, thereby mitigating the environmental risks associated with their use. Advances in agricultural practices harness the potential of these beneficial microorganisms to improve crop yields while minimizing the environmental impact. However, challenges such as competition with indigenous microbial strains and environmental factors limit the universal utilization of microbial inoculants. Despite these challenges, understanding and leveraging the interactions between plants and beneficial microorganisms hold promise for sustainable agriculture and enhanced food security.

Synergistic Effects of Salicylic Acid and Bacillus butanolivorans KJ40 for Enhancing Napa Cabbage (Brassica napa subsp. pekinensis) Resilience to Water-Deficit Stress

Climate change exacerbates drought, globally impacting crop production and necessitating the adoption of sustainable strategies. This study investigates the potential synergistic effects of salicylic acid (SA) and Bacillus butanolivorans KJ40 (KJ40) on napa cabbage (Brassica rapa subsp. pekinensis) under water-deficit stress conditions by watering withheld for five days. Results demonstrate that the combined application of KJ40 and SA, particularly at concentrations of 0.5 mM and 1 mM, significantly enhances plant growth and mitigates the negative impacts of water deficit. Moreover, the combination treatment with SA (0.5 mM) and KJ40 (1 × 108 cells/mL) reduces lipid oxidation and enhances antioxidant enzyme activity, indicating improved plant stress tolerance. Analysis of soil microbial profiles reveals alterations in metabolic activity and substrate utilization patterns, suggesting potential changes in rhizosphere dynamics. Additionally, this study examines the impact of SA on KJ40 population dynamics in soil, revealing concentration-dependent effects on bacterial survival. Overall, the combination of KJ40 and SA was effective in mitigating water-deficit stress in napa cabbage. These findings highlight the combination as a novel synergistic strategy to enhance plant resilience to water-deficit stress, offering insights into plant–microbe interactions and soil ecosystem dynamics.

Microbes and nutrient shift in a Closed Aquatic Ecosystem (CAES) during four weeks of operation

A Closed Aquatic Ecosystem (CAES) housed an aquatic plant Ceratophyllum demersum, zebrafish (Danio rerio), and microbes that were simultaneously obtained with the zebrafish, and it was used to study the operation of the ecosystem. The results indicated that the CAES can operate steadily for about 4 weeks. The dissolved oxygen (DO), pH, and conductivity values of the ecosystem regularly oscillated, while the total nitrogen of the water decreased and the total phosphate slightly increased. Additionally, the chemical oxygen demand (COD, a measure of organic compounds) of the water after the experiment increased to 39 times more than that of the water before the experiment. The meta-genomic data showed that the number of genera decreased by 38 % and the top 10 most abundant genera were almost completely different before and after the experiment, which demonstrated a great shift in the microbes during the operation process. These results suggested that although the CAES operated steadily during the 28-day experiment, there were more organic materials and less nitrogen in the water by the end of the experiment, which may have influenced the structure and operation of the ecosystem. Thus, it is necessary to remove superfluous plant biomass from the CAES and supply nitrogen to keep the ecosystem stable.

Divergent accumulation of microbial necromass and plant lignin phenol induced by adding maize straw to fertilized soils

Plant carbon (C) inputs and their subsequent microbial transformation affect the build-up process of soil organic C (SOC) pool. Nevertheless, there are knowledge gaps on how crop straw addition modifies SOC composition at molecular-level, especially in soils with different fertilization practices. Here, long-term fertilized Mollisols (unfertilized control, NF; inorganic fertilization, IF; inorganic fertilization plus manure, IFM) were incubated with or without maize straw addition in a 900-day field mesocosm experiment. The microbial necromass and plant lignin components contents were synchronously quantified based on amino sugar and lignin phenol biomarkers, respectively. And changes in SOC chemical composition were examined using solid-state 13C nuclear magnetic resonance spectroscopy. Relative to the NF treatment, long-term fertilization increased amino sugar and lignin phenol contents, and manure application enhanced the accumulation of plant lignin components more than that of microbial necromass. Compared with the NF treatment, the IF treatment decreased the relative proportion of alkyl C and SOC content, suggesting that changes in microbial necromass and lignin phenol were not always consistent with changes in SOC. For the NF and IF treatments, maize straw incorporation increased both amino sugar content and its contribution to SOC, indicating that microbial anabolism was important for SOC accumulation after adding maize straw in C-poor soils. For the IFM treatment, maize straw addition decreased lignin phenol content (27 %) and its contribution to SOC but increased the contribution of amino sugar to SOC, reflecting an enlarged contribution of microbial necromass to soil C pool formation under manure application after maize straw addition. The contribution of lignin phenol to SOC was decreased from days 360–900, whereas fungal necromass C content and the contribution of amino sugar to SOC were increased from days 360–900 under the IFM soil with maize straw addition, indicating that plant lignin components might be converted into fungal biomass and its necromass with increasing maize straw decomposition under manure application. Overall, we concluded that maize straw addition favored microbial immobilization in all fertilization treatments.

Host specificity of plant‐associated bacteria is negatively associated with genome size and host abundance along a latitudinal gradient

AbstractHost specialization plays a critical role in the ecology and evolution of plant–microbe symbiosis. Theory predicts that host specialization is associated with microbial genome streamlining and is influenced by the abundance of host species, both of which can vary across latitudes, leading to a latitudinal gradient in host specificity. Here, we quantified the host specificity and composition of plant–bacteria symbioses on leaves across 329 tree species spanning a latitudinal gradient. Our analysis revealed a predominance of host‐specialized leaf bacteria. The degree of host specificity was negatively correlated with bacterial genome size and the local abundance of host plants. Additionally, we found an increased host specificity at lower latitudes, aligning with the high prevalence of small bacterial genomes and rare host species in the tropics. These findings underscore the importance of genome streamlining and host abundance in the evolution of host specificity in plant‐associated bacteria along the latitudinal gradient.

Addressing Toxicity Concerns: State-of-the-Art Synthesis Methods and Emerging Multifaceted Applications of Silver Nanoparticles

Abstract: Silver nanoparticles (AgNPs), typically ranging in size from 10 to 1000 nm, are synthesize through physical, chemical, or biological methods. The biological approach, which often uses plant extracts, microbes, or fungi, is recommended for its eco-friendliness and lower dangers, while physical and chemical procedures can be costly and potentially dangerous. AgNPs are widely used in treatments and diagnostics in the medical field. Their exceptional antibacterial, antifungal, antiviral, anticancer, antiangiogenic, leishmanicidal, anti-inflammatory, antidiabetic, antioxidant, and anthelmintic action are just a few of their special qualities. However, AgNPs do have certain disadvantages due to worries about their nanotoxicity. This thorough study covers a wide range of AgNP topics, including their synthesis, properties, factors affecting particle size, and modes of action. Additionally, it covers their uses in the medical field, any potential toxicity issues, and the difficulties associated with their application.

Regulatory mechanisms of plant rhizobacteria on plants to the adaptation of adverse agroclimatic variables

The mutualistic plant rhizobacteria which improve plant development and productivity are known as plant growth-promoting rhizobacteria (PGPR). It is more significant due to their ability to help the plants in different ways. The main physiological responses, such as malondialdehyde, membrane stability index, relative leaf water content, photosynthetic leaf gas exchange, chlorophyll fluorescence efficiency of photosystem-II, and photosynthetic pigments are observed in plants during unfavorable environmental conditions. Plant rhizobacteria are one of the more crucial chemical messengers that mediate plant development in response to stressed conditions. The interaction of plant rhizobacteria with essential plant nutrition can enhance the agricultural sustainability of various plant genotypes or cultivars. Rhizobacterial inoculated plants induce biochemical variations resulting in increased stress resistance efficiency, defined as induced systemic resistance. Omic strategies revealed plant rhizobacteria inoculation caused the upregulation of stress-responsive genes—numerous recent approaches have been developed to protect plants from unfavorable environmental threats. The plant microbes and compounds they secrete constitute valuable biostimulants and play significant roles in regulating plant stress mechanisms. The present review summarized the recent developments in the functional characteristics and action mechanisms of plant rhizobacteria in sustaining the development and production of plants under unfavorable environmental conditions, with special attention on plant rhizobacteria-mediated physiological and molecular responses associated with stress-induced responses.

Impact of Rhizospheric Microbiome on Rice Cultivation.

The rhizosphere niche is extremely important for the overall growth and development of plants. Evidently, it is necessary to understand the complete mechanism of plant microbe interactions of the rhizosphere for sustainable and low input productivity. To meet the increasing global food demand, rice (Oryza sativa L.) agriculture seeks optimal conditions. The unique oxic-anoxic interface of rice-growing soil has invited divergent microbes with dynamic biogeochemical cycles. This review provides the systematic analysis of microbes associated with the major biogeochemical cycles with the aim to generate better management strategies of rhizospheric microbiome in the field of rice agriculture. For instance, several methanogenic and methanotrophic bacteria in the rice rhizosphere make an equilibrium for methane concentration in the environment. The carbon sequestration in paddy soil is again done through many rhizospheric microorganisms that can directly assimilate CO2 with their photoautotrophic mode of nutrition. Also the phosphate solubilizing microbes remain to be the most important keys for the PGPR activity of the paddy ecosystem. In addition, rhizospheric microbiome remain crucial in degradation and solubilization of organo-sulfur and insoluble inorganic sulfides which can be taken by the plants. Further, this review elucidates on the advantages of using metagenomic and metaproteomic approaches as an alternative of traditional approaches to understand the overall metabolic pathways operational in paddy-field. These knowledges are expected to open new possibilities for designing the balanced microbiome used as inoculum for intensive farming and will eventually lead to exert positive impacts on rice cultivation.

Implications of bacteria‒bacteria interactions within the plant microbiota for plant health and productivity.

Crop production currently relies on the widespread use of agrochemicals to ensure food security. This practice is considered unsustainable, yet has no viable alternative at present. The plant microbiota can fulfil various functions for its host, some of which could be the basis for developing sustainable protection and fertilization strategies for plants without relying on chemicals. To harness such functions, a detailed understanding of plant‒microbe and microbe‒microbe interactions is necessary. Among interactions within the plant microbiota, those between bacteria are the most common ones; they are not only of ecological importance but also essential for maintaining the health and productivity of the host plants. This review focuses on recent literature in this field and highlights various consequences of bacteria‒bacteria interactions under different agricultural settings. In addition, the molecular and genetic backgrounds of bacteria that facilitate such interactions are emphasized. Representative examples of commonly found bacterial metabolites with bioactive properties, as well as their modes of action, are given. Integrating our understanding of various binary interactions into complex models that encompass the entire microbiota will benefit future developments in agriculture and beyond, which could be further facilitated by artificial intelligence-based technologies.

Preparation of Biofertilizer with Phosphogypsum and Straw: Microbial Community Changes and Plant Growth Effects

Preparation of Biofertilizer with Phosphogypsum and Straw: Microbial Community Changes and Plant Growth Effects

Biochar boosted high oleic peanut production with enhanced root development and biological N fixation by diazotrophs in a sand-loamy Primisol

Peanut yield and quality face significant threats due to climate change and soil degradation. The potential of biochar technology to address this challenge remains unanswered, though biochar is acknowledged for its capacity to enhance the soil microbial community and plant nitrogen (N) supply. A field study was conducted in 2021 on oil peanuts grown in a sand-loamy Primisol that received organic amendments at 20 Mg ha−1. The treatments consisted of biochar amendments derived from poultry manure (PB), rice husk (RB), and maize residue (MB), as well as manure compost (OM) amendment, compared to no organic amendment (CK). In 2022, during the second year after amendment, samples of bulk topsoil, rooted soil, and plants were collected at the peanut harvest. The analysis included the assessment of soil quality, peanut growth traits, microbial community, nifH gene abundance, and biological N fixation (BNF) rate. Compared to the CK, the OM treatment led to an 8 % increase in peanut kernel yield, but had no effect on kernel quality in terms of oil production. Conversely, both PB and MB treatments increased kernel yield by 10 %, whereas RB treatment showed no change in yield. Moreover, all biochar amendments significantly improved oilseed quality by 10–25 %, notably increasing the proportion of oleic acid by up to 70 %. Similarly, while OM amendment slightly decreased root development, all biochar treatments significantly enhanced root development by over 80 %. Furthermore, nodule number, fresh weight per plant, and the nifH gene abundance in rooted soil remained unchanged under OM and PB treatments but was significantly enhanced under RB and MB treatments compared to CK. Notably, all biochar amendments, excluding OM, increased the BNF rate and N-acetyl-glucosaminidase activity. These changes were attributed to alterations in soil aggregation, moisture retention, and phosphorus availability, which were influenced by the diverse physical and chemical properties of biochars. Overall, maize residue biochar contributed synergistically to enhancing soil fertility, peanut yield, and quality while also promoting increased root development, a shift in the diazotrophic community and BNF.

AMF symbiosis drives the rhizosphere microbiome to synergistically improve herbage growth in saline–alkaline soils

AbstractPlant–microbe interactions are essential in shaping plant performance and overall ecosystem functioning. However, the regulatory mechanisms underlying plant–microbe interactions mediated by mycorrhizal symbiosis in saline–alkaline soils are still not fully understood. Here, we aimed to clarify the synergistic regulatory mechanism through which arbuscular mycorrhizal fungi (AMF) symbiosis drives the rhizosphere microbiome to improve perennial herbage growth in saline–alkaline soils and evaluate phytoremediation efficiency. This study revealed that Funneliformis mosseae inoculation (i) strongly promoted the growth of all three herbage species (with values ranging from 21.62% to 233.33%), Na+ accumulation in plants (with values ranging from 24.63% to 188.89%), and decreased soil electrical conductivity (with values ranging from 7.68% to 12.87%), potentially suggesting improved phytoremediation efficiency with AMF symbiosis; (ii) increased nutritional content and decreased C:P and N:P ratios (with values ranging from 27.20% to 92.87%) and improved K+/Na+ and P/Na+ ratios (with values ranging from 2.60% to 302.96%); (iii) increased the abundance of some beneficial bacterial taxa and strengthened the significant strong relationships among most of these bacteria and plant biomass, ion homeostasis as well as stoichiometric ratio constants, and AMF inoculation treatments also consisted the higher proportion of differential genera significantly correlated with these plant factors as well as plant nutrient contents, potentially reflecting that AMF mediated the enrichment process of beneficial bacterial taxa and may strength functional interaction between plant and bacterial taxa, which may be importance for the enhancement of saline–alkaline tolerance of plants; and (iv) enhanced stability of the rhizosphere bacterial community and complexity of interaction networks, and the related indictors also established significant correlations with plant/soil factors, suggesting that the improvement of stability and functional complexity driven by AMF may also be beneficial for enhancing phytoremediation efficiency. These findings indicate that AMF inoculation plays its own beneficial role by simultaneously activating the potential of beneficial rhizosphere bacterial taxa and that their synergistic interaction is more beneficial for enhancing plant growth in salt‐affected soils and enhancing phytoremediation efficiency. This study helps to elucidate the underlying mechanisms through which AMF‐mediated rhizosphere bacterial community improve plant growth and tolerance to saline–alkaline stresses, and provides evidence that effective ecological restoration of saline–alkaline degraded grasslands can be achieved via the use of mycorrhizal symbiosis herbage.

Effects of nitrogen regulation on heavy metal phytoextraction efficiency (Leucaena leucocephala): Application of a nitrogen fertilizer and a fungal agent

Lead (Pb) and cadmium (Cd) have been identified as the primary contaminants in soil, posing potential health threats. This study aimed to examine the effects of applying a nitrogen fertilizer and a fungal agent Trichoderma harzianum J2 (nitrogen alone, fungi alone, and combined use) on the phytoremediation of soils co-contaminated with Pb and Cd. The growth of Leucaena leucocephala was monitored in the seedling, differentiation, and maturity stages to fully comprehend the remediation mechanisms. In the maturity stage, the biomass of L. leucocephala significantly increased by 18% and 29% under nitrogen-alone (NCK+) and fungal agent-alone treatments (J2), respectively, compared with the control in contaminated soil (CK+). The remediation factors of Pb and Cd with NCK+ treatment significantly increased by 50% and 125%, respectively, while those with J2 treatment increased by 73% and 145%, respectively. The partial least squares path model suggested that the nitrogen-related soil properties were prominent factors affecting phytoextraction compared with biotic factors (microbial diversity and plant growth). This model explained 2.56 of the variation in Cd concentration under J2 treatment, and 2.97 and 2.82 of the variation in Pb concentration under NCK+ and J2 treatments, respectively. The redundancy analysis showed that the samples under NCK+ and J2 treatments were clustered similarly in all growth stages. Also, Chytridiomycota, Mucoromucota, and Ciliophora were the key bioindicators for coping with heavy metals. Overall, a similar remediation mechanism allowed T. harzianum J2 to replace the nitrogen fertilizer to avoid secondary pollution. In addition, their combined use further increased the remediation efficiency.

NanoBiofertilizer and its Application in Sustainable Agriculture, Crop Specific Nutrients Delivery and Environmental Sustainability: A Review

Probiotic bacteria are increasingly in demand in the food and feed industries. A growing population and finite resources require efficient ways to maximize yields. Probiotic bacteria are gaining popularity in the food and feed industries due to their unique combination of benefits and values, which include consumer health interests, sustainability values, food innovation, and potential business opportunities. The use of conventional fertilizers can increase crop production but can also cause runoff and toxicity issues. A nanobiofertilizer offers improved crop nutrition and reduces application rates. Slow-release properties minimize environmental losses while nanoscale particle size enhances nutrient absorption. If nanobiofertilizers are closely regulated, they can boost yields without destroying the soil and aquatic ecosystems. In recent years, nanobiofertilizers have received considerable attention. Plant extracts and microbes are used in green synthesis to produce eco-friendly nanoparticles. Crop-specific nutrient release can be tailored using modified nanoparticle surfaces. Controlled nutrient delivery is achieved by smart nanocarrier systems that adapt to changing soil moisture, pH, and microbial activity. Combined applications of plant growth-promoting rhizobacteria have been reported that they can enhance crop growth in synergy. This review presents an overview of the most recent studies on nanobiofertilizers, as well as the issues connected with their environmental implications, safety, and regulation, presenting a roadmap for the responsible use of nanobiofertilizers, which aims to enhance food security while protecting the environment for future generations.

Disease-induced changes in bacterial and fungal communities from plant below- and aboveground compartments

The plant microbes are an integral part of the host and play fundamental roles in plant growth and health. There is evidence indicating that plants have the ability to attract beneficial microorganisms through their roots in order to defend against pathogens. However, the mechanisms of plant microbial community assembly from below- to aboveground compartments under pathogen infection remain unclear. In this study, we investigated the bacterial and fungal communities in bulk soil, rhizosphere soil, root, stem, and leaf of both healthy and infected (Potato virus Y disease, PVY) plants. The results indicated that bacterial and fungal communities showed different recruitment strategies in plant organs. The number and abundance of shared bacterial ASVs between bulk and rhizosphere soils decreased with ascending migration from below- to aboveground compartments, while the number and abundance of fungal ASVs showed no obvious changes. Field type, plant compartments, and PVY infection all affected the diversity and structures of microbial community, with stronger effects observed in the bacterial community than the fungal community. Furthermore, PVY infection, rhizosphere soil pH, and water content (WC) contributed more to the assembly of the bacterial community than the fungal community. The analysis of microbial networks revealed that the bacterial communities were more sensitive to PVY infection than the fungal communities, as evidenced by the lower network stability of the bacterial community, which was characterized by a higher proportion of positive edges. PVY infection further increased the bacterial network stability and decreased the fungal network stability. These findings advance our understanding of how microbes respond to pathogen infections and provide a rationale and theoretical basis for biocontrol technology in promoting sustainable agriculture.Key points• Different recruitment strategies between plant bacterial and fungal communities.• Bacterial community was more sensitive to PVY infection than fungal community.• pH and WC drove the microbial community assembly under PVY infection.

Interplay between green-synthesized nanoparticles and plant performance is mediated by the microbial community in the rhizocompartments

Numerous green-synthesized nanoparticles are being evaluated for their potential application in soil, yet understanding their influence on plant performance and their rhizocompartments associated microbes is a gap that needs to be addressed. In this study, we investigated how applying iron oxide nanoparticles (control 0, low 25 and high 50 mg/kg) impacted the rhizocompartments associated microbial communities and plant secondary metabolites grown in natural soil microcosm. The transcriptional analysis showed that the majority of artemisinin and flavonoid biosynthetic pathway genes were significantly upregulated in plants with the application of low concentration of green-synthesized iron oxide nanoparticles (FeO.NPs) when compared with control plants, suggesting a fine collaboration between these metabolites’ pathways, as indicated by a remarkable increase in artemisinin content (2-fold), ferulic acid (7.6-fold), luteolin (4.3-fold) and syringic acid (6.2-fold). The response of rhizocompartments microbial communities and associated soil enzymes was investigated using high-throughput sequencing and profiler test kits, respectively. The soil microbial community structure was altered upon FeO.NPs exposure in both low and high treated soils as indicated by multivariate analysis. For instance, bacterial phyla Bacteroidetes and Gemmatimonadetes and fungal phyla Ascomycota demonstrated a significant rise in relative abundance in both the rhizosphere and rhizoplane in low and high treatments relative to the control. Moreover, genera level analysis revealed that Cupriavidus, Vibrionimonas, and Burkholderia displayed higher relative abundance (p < 0.05) in low FeO.NPs concentration while Giaella and Nonomuraea didn't show any noticeable response to FeO.NPs. In terms of fungal genera, Oidiodendron and Cryptococcus showed high relative abundance under low treatment. The altered microbiome profile is possibly associated with soil enzymes, for instance, urease and catalase activities were increased by 1.76 and 1.71-fold, respectively in low FeO.NPs. Thus, this study demonstrates the effects of FeO.NPs gradients on plant secondary metabolites and soil enzyme activities, while contributing new insights into their specific impacts on the microbial community composition in the rhizocompartments of plant root system.

Assembly and succession of the phyllosphere microbiome and nutrient-cycling genes during plant community development in a glacier foreland

The phyllosphere, particularly the leaf surface of plants, harbors a diverse range of microbiomes that play a vital role in the functioning of terrestrial ecosystems. However, our understanding of microbial successions and their impact on functional genes during plant community development is limited. In this study, considering core and satellite microbial taxa, we characterized the phyllosphere microbiome and functional genes in various microhabitats (i.e., leaf litter, moss and plant leaves) across the succession of a plant community in a low-altitude glacier foreland. Our findings indicate that phyllosphere microbiomes and associated ecosystem stability increase during the succession of the plant community. The abundance of core taxa increased with plant community succession and was primarily governed by deterministic processes. In contrast, satellite taxa abundance decreased during plant community succession and was mainly governed by stochastic processes. The abundance of microbial functional genes (such as C, N, and P hydrolysis and fixation) in plant leaves generally increased during the plant community succession. However, in leaf litter and moss leaves, only a subset of functional genes (e.g., C fixation and degradation, and P mineralization) showed a tendency to increase with plant community succession. Ultimately, the community of both core and satellite taxa collaboratively influenced the characteristics of phyllosphere nutrient-cycling genes, leading to the diverse profiles and fluctuating abundance of various functional genes during plant community succession. These findings offer valuable insights into the phyllosphere microbiome and plant–microbe interactions during plant community development, advancing our understanding of the succession and functional significance of the phyllosphere microbial community.

NRT1.1B mediates rice plant growth and soil microbial diversity under different nitrogen conditions

Interactions between microorganisms and plants can stimulate plant growth and promote nitrogen cycling. Nitrogen fertilizers are routinely used in agriculture to improve crop growth and yield; however, poor use efficiency impairs the optimal utilization of such fertilizers. Differences in the microbial diversity and plant growth of rice soil under different nitrogen application conditions and the expression of nitrogen-use efficiency-related genes have not been previously investigated. Therefore, this study investigates how nitrogen application and nitrogen-use efficiency-related gene NRT1.1B expression affect the soil microbial diversity and growth indices of two rice varieties, Huaidao 5 and Xinhuai 5. In total, 103,463 and 98,427 operational taxonomic units were detected in the soils of the Huaidao 5 and Xinhuai 5 rice varieties, respectively. The Shannon and Simpson indices initially increased and then decreased, whereas the Chao and abundance-based coverage estimator indices decreased after the application of nitrogen fertilizer. Nitrogen fertilization also reduced soil bacterial diversity and richness, as indicated by the reduced abundances of Azotobacter recorded in the soils of both rice varieties. Nitrogen application initially increased and then decreased the grain number per panicle, yield per plant, root, stem, and leaf nitrogen, total nitrogen content, glutamine synthetase, nitrate reductase, urease, and root activities of both varieties. Plant height showed positive linear trends in response to nitrogen application, whereas thousand-grain weights showed a negative trend. Our findings may be used to optimize nitrogen fertilizer use for rice cultivation and develop crop-variety-specific strategies for nitrogen fertilizer application.

Root uptake of umbelliferone enhances pea's resistance against root-knot nematodes

Coumarins are secondary plant metabolites which play a key role in plant–plant and plant–microbe interactions. In particular, they are highly involved in environmental stress responses. Coumarins can transfer from plants producing coumarins to non-coumarin-producing neighbouring plants. As in vitro studies have shown that coumarins are nematicidal, we hypothesized that this transfer may also result in enhanced resistance against plant parasitic nematodes in coumarin-receiving plants. To test if the uptake of coumarins in a non-coumarin- producing plant protects the plant against nematode attack, we incubated non-coumarin- producing pea seedlings in growth media with the coumarin umbelliferone for three weeks, after which the plants were transplanted into soil and inoculated with root-knot nematodes (Meloidogyne incognita). We quantified the coumarin content in pea organs and nematode root invasion 2, 4, and 6 weeks after transplantation. Umbelliferone was taken up by the pea roots and translocated to the shoots. As a result of metabolization, umbelliferone and its derived metabolites coumarin, scopoletin, and scopolin were detected in the plants. The root uptake of umbelliferone reduced root-knot nematode invasion significantly up to 4 weeks after the root exposure. Our results suggest that the root uptake and the transfer of bioactive compounds between plants can expand the understanding of plant–plant interactions.