Plant-soil Interactions Research Articles

Employing stable isotopes to reveal temporal trajectories of water travelling through the soil–plant-atmosphere continuum

The spatiotemporal patterns of water travelling through the soil–plant-atmosphere continuum (SPAC) have received much attention due to the frequency of extreme weather and water scarcity. However, the interconnections and transboundary transport of specific compartments within the hydrologic cycle are poorly understood. We portrayed the propagation paths of water isotope signals by analyzing isotopes of precipitation, soil water, and xylem water. The isotope sine curves analysis method was improved to quantify water transfer efficiency, mean transmission time from precipitation to soil (MTT1), mean transmission time from soil to trees (MTT2), mean residence time within soil (MRTSW), and mean residence time within tree xylems (MRTXY). The temporal trajectory of water traveling through SPAC was depicted, and its influencing factors and intrinsic mechanisms were explored. Our results showed that (1) water isotopes were blocked when crossing water pools (precipitation, soil water, and xylem water) and the transfer efficiency was progressively weaker (85.5 %→13.5 %). (2) The MTT1 was significantly and positively correlated with soil porosity (Spearman correlation coefficient, 0.551). Its spatiotemporal pattern (0.8–15.9d) indicated that the transport and mixing of soil water involved two modes: displacement flow and bypass flow. The MTT2 (−13.2d–4.3d) of Platycadus orientalis was in general smaller than that of Quercus variabilis (−4.7d–11.5d). (3) The MRT (35.2d–343.8d) was influenced by a combination of soil physicochemical properties, root distribution, and tree morphological traits. Our study shows that connectivity between pools is better reflected with transfer efficiency. Comparing MTT and MRT of P. orientalis and Q. variabilis, tree hydrodynamic processes were quantified, and P. orientalis was more sensitive to seasonal moisture variability. Additionally, our study improved the understanding of the “black box” within the hydrological interface of plant-soil interactions.

Altitude Distribution Patterns and Driving Factors of Rhizosphere Soil Microbial Diversity in the Mountainous and Hilly Region of Southwest, China

The distribution characteristics of the microbial community in rhizosphere soils of different altitudinal gradients were explored to uncover ecological factors affecting microbial community composition. In this study, the community variations of bacteria and fungi in the rhizosphere soil of Chrysanthemum indicum L. were analyzed. Samples were distributed along an altitudinal gradient of 300–1500 m above sea level in the Fuling watershed of the Three Gorges Reservoir area, China. The analysis was conducted using Illumina MiSeq high-throughput sequencing and bioinformatics analyses. Through correlation analysis with ecological factors, the altitude distribution pattern and driving factors of soil microbial diversity in the mountainous and hilly region of Chongqing were explored. According to the results, the richness and diversity of rhizosphere soil bacteria increased with altitude, while fungi were the richest and most diverse at an altitude of 900 m. The composition of the microbial community differed among different altitudes. Actinobacteria, Proteobacteria, Acidobacteriota, Chloroflexi, Bacteroidota, Ascomycota, unclassified_k_Fungi, Basidiomycota, and Mortierellomycota dominated the microbial community in rhizosphere soil. Correlation analysis showed that the distribution of rhizosphere soil microbial communities correlated with soil ecological factors at different altitudes. Moisture, pH, total nitrogen, total potassium, available potassium, urease, and catalase were significantly positively correlated with rhizosphere soil bacterial α-diversity, while their correlations with fungi were not significant. Variation partition analysis showed that the combined effects of soil physical and chemical factors, enzyme activity, and microbial quantity regulated bacterial community structure and composition. Their combined contributions (19.21%) were lower than the individual effects of soil physical and chemical factors (48.49%), enzyme activity (53.24%), and microbial quantity (60.38%). The effects of ecological factors on fungal communities differed: While the soil physical and chemical factors (44.43%) alone had a clear effect on fungal community structures, their combined contributions had no apparent effect. The results of this study not only contribute to a deeper understanding of the impact mechanism of altitude gradient on the diversity of rhizosphere soil microbial communities, but also provide a scientific basis for the protection and management of mountainous and hilly ecosystems. It lays a foundation for the future exploration of the relationship between microbial communities and plant–soil interactions.

The Application of Rain Gardens in Urban Environments: A Bibliometric Review

The increasing challenges of urbanization and climate change have driven the need for innovative stormwater management solutions. Rain gardens, as a nature-based solution (NBS), have emerged as a critical component in urban water management, particularly in enhancing hydrological regulation, water quality, and ecosystem services. This bibliometric review examines the application of rain gardens in urban environments, focusing on their roles in stormwater management, pollutant removal, and ecological enhancement. Data from 728 academic papers published between 2000 and 2023 were analyzed using the Web of Science (WoS) Core Collection, employing bibliometric tools such as the “Bibliometrix” R package and CiteSpace. The analysis highlights the increasing global interest in rain gardens, particularly since 2015, with China and the United States leading research efforts. Key findings reveal that rain gardens significantly reduce runoff, improve water quality, and contribute to urban biodiversity. In addition, their integration into public spaces offers landscape esthetics and social benefits, enhancing the quality of life in urban areas. However, challenges remain in optimizing their design for diverse climates and long-term performance. The study underscores the need for further research on plant–soil interactions, pollutant removal mechanisms, and the broader ecological and social contributions of rain gardens. This review provides insights into the evolution of rain garden research and identifies future directions for advancing sustainable urban stormwater management.

Relationship between root system-soil C:N:P and soil microbial diversity at different evolutionary stages of Caragana tibetica scrub in arid desert grassland, Northern China.

Scrub root systems play a crucial role in preventing soil erosion and nutrient loss. However, the effects of the root system configuration on soil nutrient dynamics and microbial changes at various evolutionary stages remain poorly understood. In this study, we investigated the relationship between soil physical and chemical properties and the diversity of bacteria and fungi throughout the evolutionary stages of the scrub root systems. This was achieved through a combination of whole-root excavation and root tracing techniques. The results indicated that root diameter was the main factor contributing to the continuous increase in carbon (C): phosphorus (P) and nitrogen (N): P ratios as the scrub sand pile developed. The soil organic carbon (SOC), total soil nitrogen (TN), and total soil phosphorus (TP) contents in the soil in the four evolutionary stages were the highest during the developmental stage, but the change in TP content was not statistically significant (P > 0.05). Partial least squares path modeling and redundancy analysis (RDA) indicated that root system stoichiometric C and N contents were positively correlated with microbial diversity (R2 = 0.85). There was no correlation between the evolutionary stage and soil nutrient TN, whereas soil nutrient TN was negatively correlated with microbial diversity (R2 = -0.92). These findings elucidate the relationship between the evolutionary stage of root chemical measurement characteristics, soil elements and microorganisms, and their subsequent effects on root elemental composition and microbial diversity. This study enhances the current understanding of plant-soil interactions in desert steppe ecosystems.

Unveiling the Behavior of an Endangered Facultative Cuprophyte Coincya Species in an Abandoned Copper Mine (Southeast Portugal).

Plant-soil interactions of endangered species with a high-priority conservation status are important to define in situ and ex situ conservation and restoration projects. The threatened endemic Coincya transtagana, thriving in the southwest of the Iberian Peninsula, can grow in metalliferous soils. The main goal of this study was to investigate the behavior of this species in soils rich in potentially toxic elements in the abandoned Aparis Cu mine. Soil samples were characterized for physicochemical properties and multielemental composition, as well as biological activity, through an analysis of enzymatic activities. Plant biomass was assessed, and multielemental analysis of the plants was also performed. The mine soils had slightly basic pH values and were non-saline and poor in mineral N-NH4, with medium-to-high organic matter concentration and medium cation-exchange capacity. In these soils, dehydrogenase had the highest activity, whereas protease had the lowest activity. The total concentrations of Cu (1.3-5.9 g/kg) and As (37.9-118 mg/kg) in soils were very high, and the available fraction of Cu in the soil also had high concentration values (49-491 mg/kg). Moreover, this study shows for the first time that C. transtagana had high uptake and translocation capacities from roots to shoots for Cu, Ni, and Cr. Although Cu in the plants' aerial parts (40-286 mg/kg) was considered excessive/toxic, no signs of plant toxicity disorders or P uptake reduction were detected. This preliminary study revealed that C. transtagana is Cu-tolerant, and it could be used for phytoremediation of soils contaminated with potentially toxic elements, while also contributing to its conservation.

Plant investigation and the impact on earthen site soil properties in the east city wall of the Sanxingdui site

In southern China, vegetation on exposed earthen sites serves not only to mitigate erosion but also alters their visual appearance, leading to biodeterioration. However, how plants influence the properties of earthen sites is virtually unknown. This study undertook an ecological investigation of the original habitat in the east city wall of the Sanxingdui site, analyzing its soil properties and investigating plant-soil interactions. Research findings indicate that existing plant communities are not conducive to biodiversity nor site presentation. Plants exert a direct influence within a vertical range extending 0–40 cm beneath the site; root content correlates negatively with soil pH value but positively with organic matter content. The herbaceous community (E-2 and E-3) exhibits higher clay content than the arbor community (E-1) within this range. The above conclusions exhibit statistical significance. This study offers a scientific elucidation of the ecological parameters governing plant communities concerning the conservation of earthen sites, and provides an initial influence range of plant communities and biodegradation on the east city wall of the Sanxingdui sites, thereby revealing the technical potential for employing plants as a soft capping for earthen sites in the open air from the function method.

CHEMOMETRIC EVIDENCE FOR SR AND RB ISOTOPES DUE TO THE SPECIFIC SOIL CHEMISTRY IN DIFFERENT GEOGRAPHICAL REGIONS

Strontium and rubidium are the commonly used metals for isotope-ratio analysis. Moreover, this geochemical marker varies between different rock types and formations. The 87Sr/86Sr ratio has been shown to vary widely in surface rocks, so any Sr released into soils, rivers, and groundwater has an isotopic signature that reflects its source. Sr and Rb isotopes have also been used to trace agricultural products, which have incorporated Sr, along with Ca, from soils incorporating the Sr-isotope ratios of the underlying rocks. The specific conditions in the soil represent characteristic conditions of the environment which is reflected in a certain way in the plants. Despite uncertainty about the organic compounds in a sample, the content of selected elements (trace and rare earth elements, REEs) reflects the growing conditions in the environment. For that instance, in the present research, we will give focus on the inorganic compounds’ identifications, due to the more stable response to the lithogenic nature of the soil-plant interaction. For the present study, the target isotopes were 88Sr, 87Sr, 86Sr, and 85Rb. The isotope analysis was conducted with the application of ICP-MS, following the protocol provided in the EPA METHOD 6020. In the validation process, no significant interference occurred that could affect the sensitivity of the measurement of the selected isotopes. Data analysis has been applied to the comparative issues between Sr and Rb content in soil from North Macedonia and selected regions in China. Moreover, the same chemometric model was applied for data analysis for selected plant species for both regions. Data analyses has improved the significant differences within the element contents and ratios as well between both geographical regions.

Mechanisms of ROS-mediated interactions between Bacillus aryabhattai LAD and maize roots to promote plant growth

BackgroundPlant growth-promoting rhizobacteria (PGPR), as a group of environmentally friendly bacteria growing in the rhizosphere of plants, play an important role in plant growth and development and resistance to environmental stresses. However, their limited understanding has led to the fact that their large-scale use in agriculture is still scarce, and the mechanisms by which beneficial bacteria are selected by plants and how they interact with them are still unclear.MethodIn this study, we investigated the interaction between the auxin-producing strain Bacillus aryabhattai LAD and maize roots, and performed transcriptomic and metabolomic analyses of Bacillus aryabhattai LAD after treatment with maize root secretions(RS).ResultsOur results show that there is a feedback effect between the plant immune system and bacterial auxin. Bacteria activate the immune response of plant roots to produce reactive oxygen species(ROS), which in turn stimulates bacteria to synthesize IAA, and the synthesized IAA further promotes plant growth. Under the condition of co-culture with LAD, the main root length, seedling length, root surface area and root volume of maize increased by 197%, 107%, 89% and 75%, respectively. In addition, the results of transcriptome metabolome analysis showed that LAD was significantly enriched in amino acid metabolism, carbohydrate metabolism and lipid metabolism pathways after RS treatment, including 93 differentially expressed genes and 45 differentially accumulated metabolites.ConclusionOur findings not only provide a relevant model for exploring the effects of plant-soil microbial interactions on plant defense functions and thereby promoting plant growth, but also lay a solid foundation for the future large-scale use of PGPR in agriculture for sustainable agricultural development.

A Review of Discrete Element Method Applications in Soil–Plant Interactions: Challenges and Opportunities

The discrete-element method (DEM) has become a pivotal tool for investigating soil–plant interactions in agricultural and environmental engineering. This review examines recent advancements in DEM applications, focusing on both the challenges and opportunities that shape future research in this field. This paper first explores the effectiveness of DEM in simulating soil and plant materials, including seeds, roots, and residues, highlighting its role in understanding interactions that affect agricultural practices. Challenges such as long computation times and the complexity of determining accurate contact parameters are discussed, alongside emerging methods like machine learning that offer potential solutions. Notable advancements include the integration of machine learning algorithms for contact parameter estimation, the use of expanded particle models for dynamic processes, and the development of new techniques for detailed post-processing of DEM simulations. The review also identifies key future research directions, including the incorporation of environmental factors such as air and water, and the exploration of residue management for carbon storage and erosion prevention. By addressing these challenges and seizing these opportunities, future research can enhance the accuracy and applicability of DEM models, advancing our understanding of soil–plant interactions and contributing to more sustainable agricultural and environmental practices.

Fractional Order Commensurate Model of Contaminated Soil–Plant Interaction with Non-singular Kernel

Fractional Order Commensurate Model of Contaminated Soil–Plant Interaction with Non-singular Kernel

Enhancing Soil Resilience and Sugar Beet (Beta vulgaris L.) Yield: Mid‐Term Effects of Compost and Glauconite Integration

ABSTRACTSugar beet (Beta vulgaris L.) is a globally significant crop, valued for its economic importance in sugar production. Saline‐sodic soil environments negatively impact sugar beet productivity. This study investigates the effects of using compost, glauconite enriched‐K and their combinations in mitigating the saline‐sodic soil environment, sugar beet productivity and extracted sugar quality. A two‐season field experiment in split‐plot design with the main plots is three doses of compost: control (C0), recommended (100%) dose (C1) and 150% recommended dose (C2). Each group divided into four subplots of glauconite treatments arranged according to the recommended dose of potassium (K) as follows: G0 (no glauconite), G1 (50% K), G2 (100% K, 480 Kg glauconite Fed−1) and G3 (150% K). The results showed that compost and glauconite mitigated adverse soil effects caused by salinity and sodicity. The C2G3 treatment reduced electrical conductivity (EC) and exchangeable sodium percentage (ESP), improved organic matter and enhanced soil bulk density, porosity and penetration resistance. This combination also increased soil nutrients (N, K, Fe, Mn, Zn and Cu). Regarding the sugar beet yield, C2G3 improved root yield, top yield, sugar yield and extracted sugar. The application of glauconite increased root diameter by 20% and root length by 23%, enhanced sugar quality with minimal sugar losses to molasses (2.43%), and reduced impurities of K, α‐amino N and Na. Principal component analysis showed positive correlations between root yield and soil potassium, organic matter, cation exchange capacity and soil porosity, with negative correlations to bulk density, EC, pH and ESP. Two‐way analysis of main (ANOM) illustrated significant effects of compost and glauconite on soil–plant interactions. Multivariate analysis indicated that higher glauconite doses significantly enhanced root yield. The Gag run charts confirmed that compost (100%) and G3 levels explored more homogeneity reducing the ESP%, increasing sugar beet root yield, sugar yield and quality.

Plant phenology modulates and undersown cover crops mitigate N2O emissions

Mitigation of N2O emissions, a potent greenhouse gas, remain challenging due to knowledge gaps in plant-mediated nitrogen (N) transformation pathways, which limits ability to identify optimal approaches for efficient N utilization. We set up mesocosms with barley, Italian ryegrass, and barley in combination with Italian ryegrass to assess role of cover crop in N2O emission mitigation. Soil emitted N2O was collected simultaneously from the pots with plants at three growth stages: namely, vegetative, canopy expansion, and grain filling. The gas sample N2O contents, N in microbial biomass (MBN), mineral N content, and phospholipid fatty acid (PLFA) analysis in soils were determined at the three growth stages. Cumulatively, highest N2O was emitted from soil under Italian ryegrass (0.056 mg N g−1 soil) followed by barley (0.0051 mg N g−1 soil) and the least under barley and Italian ryegrass combination (0.0014 mg N g−1 soil). The high emissions under Italian ryegrass occurred at vegetative stage due to high reactive N availability. Strong emissions were observed at canopy expansion stage under barley and were linked to access to the large mineral N proportion redistributed to the lower depth as depicted by highest MBN (0.025 mg N g−1 soil) and decreased extractable N (0.0068 mg N g−1 soil). The high emissions under barley correlated with high fungal/bacterial ratio, pointing towards a fungal role in the emissions. The least soil N2O emissions under barley and Italian ryegrass combination were accompanied by elimination of variations induced by the plant growth stages. Absence of 18:2ω6,9 fungal PLFA biomarker under barley and Italian ryegrass combination indicates a potential inhibition and corresponds with reduced N2O emissions. Together, these results broaden our understanding on how plant-soil interactions drives N2O emissions processes and improves our ability to identify optimal plant-based emission mitigation approaches.

Phenological stages of wheat modulate effects of phosphorus fertilization in plant-soil microbial interactions

Abstract Aims Future phosphorus (P) fertilizer availability faces challenges due to limited phosphate rock mines and strict quality regulations regarding Cd contents in phosphate rock. In this study, conventional fertilization was partially substituted with meat bone meal (MBM), sludge (S), and the organo-mineral combination of S plus MBM (SMBM), in a wheat agroecosystem. Methods We investigated the impact of fertilization treatments and crop phenological stages on P availability, crop yield, and soil microbial responses. Analysis included enzyme activities, microbial biomass, and the composition of bacterial and fungal communities using metabarcoding. Additionally, we estimated functional genes related to the P cycle through qPCR. Crop yield and nutrient content in plants and soil were also determined. Results Replacing traditional fertilization with MBM and SMBM maintained crop yield at levels equivalent to conventional fertilization. S and SMBM produced 70% and 40% (respectively) more bioavailable P compared to conventional treatment (Trad). Significant differences between treatments in soil microbial biomass were observed in the flag leaf stage. S increased in 20% total soil microbial biomass compared to Trad. Crop phenology had a stronger impact on bacterial and fungal communities than fertilization treatments. The use of S enhanced microbial biomass and activity. Yield in both MBM and SMBM plots exhibited no statistically significant differences compared to traditional fertilization. Conclusion Organo-mineral fertilization emerges as a sustainable strategy for maintaining crop production while improving soil functionality. Our findings emphasize the primary influence of crop phenology on shaping soil microbial communities and influencing microbial biomass and functionality.

Soil Fungal Pathogens in Pinus pinaster Mature Reforestation: Silvicultural Treatments Effects.

Soil fungal communities play a key role in multiple functions and ecosystem services within forest ecosystems. Today, forest ecosystems are subject to multiple environmental and anthropogenic disturbances (e.g., fire or forest management) that mainly lead to changes in vegetation as well as in plant-soil interactions. Soil pathogens play an important role in controlling plant diversity, ecosystem functions, and human and animal health. In this work we analyzed the response of soil plant pathogenic fungi to forest management in a Pinus pinaster reforestation. We started from an experimental design, in which forest thinning and gap cutting treatments were applied at different intensities and sizes, respectively. The fungal communities of plant pathogens in spring were described, and the effect of the silvicultural treatments was evaluated 5 years after their application, as were the possible relationships between soil plant pathogenic fungal communities and other environmental factors. Only a strong low thinning treatment (35% basal area) was able to generate homogeneous changes in soil pathogenic diversity. In the gaps, only the central position showed significant changes in the soil plant pathogenic fungi community.

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment

The increasing atmospheric CO2 concentration is a global concern that affects the plant-bacteria-soil system. Previous studies have investigated plant growth and bacteria activity under CO2 enrichment. However, the effects of coupled elevated CO2 and biochar amendment on the interactions of soil and medicinal plants are not well understood. This study aims to investigate the medicinal plant-soil hydraulic interactions and rhizosphere bacteria communities under coupled CO2 enrichment and biochar conditions. Two levels of CO2 concentration (400, 1000 ppm) and two biochar dosages (3%, 5% by mass) were considered. Pseudostellaria heterophylla was used as the tested medicinal plant. During plant growth, coupled CO2 enrichment and biochar at 3% and 5% dosage increased the volumetric water content at a matric suction of 33 kPa by 97% and 82% respectively, which indicates enhanced water retention. The transpiration rate of P. heterophylla was slightly reduced by 11–30% with an increase in biochar dosage due to higher total suction, while it was significantly reduced by up to 57% due to CO2 enrichment. In the rhizosphere of P. heterophylla, elevated CO2 (1000 ppm) coupled with 3% biochar dramatically increase the relative abundance of Thaumarchaeota, which played an important role in C and N cycles. Moreover, coupled CO2 enrichment and biochar addition resulted in the highest bacterial richness, while 3% biochar at ambient CO2 induced the highest bacterial diversity. This study provides a basis for understanding the medicinal plant-bacteria-soil system under CO2 enrichment and biochar conditions.

Responses of Soil Carbon and Nitrogen Dynamics and GHG Fluxes in Forest Ecosystems to Climate Change and Human Activity

Forest soils are considered the largest carbon and nitrogen pools in soil organic matter among terrestrial ecosystems, and soil carbon and nitrogen dynamics and greenhouse gas (GHG) emissions are normally affected by climate change and human activity. The collection of recent research on this scientific theme would provide a basis for understanding the responses of soil carbon and nitrogen dynamics and GHG fluxes in forest ecosystems to climate change and human activity. A Special Issue was, thus, organized to discuss recent research achievements, including a total of nine research articles and one review. This Special Issue includes the effects of climate changes such as changes in throughfall, snow cover, and permafrost degradation; human activities such as nitrogen and/or phosphorus addition and the use of biochar; and soil–plant interactions on soil carbon and nitrogen dynamics and GHG fluxes in forest ecosystems. Although this collection of papers reflects only a small part of this scientific theme, it can, to some extent, provide a basis for understanding some important research aspects related to the future of forest soil carbon and nitrogen dynamics and GHG fluxes in a changing world, thereby enabling sustainable development and the mitigation of climate change.

Effect of zeolite and irrigation treatments on grapevine leaves, an interdisciplinary approach

Abstract Aims Global warming depicts a real challenge for viticulture. As found by PubMed results, a 90% increase in the abiotic stress publications number from 2015 onwards is registered. Soil and grapevine response interaction to abiotic stress is arbitrated by an intricate signal transduction network that determines adaptive changes and modifications in gene expression mediated by the transcription factors (WRKY proteins). Briefly, (i) Does zeolite application affect canopy and biochemical leaf components? (ii) Is it possible to start a gene expression approach in an open-field vineyard, without fixed and stable external parameters obtaining an interconnected net of interdisciplinary data? (iii) Could the zeolite application be a corroborant tool to maintain a state of homeostasis in grapevine? Methods After a soil clinoptilolite treatment (the "Roca magica" well known as water moderator) and/or irrigation utilizing vines presented to drought and high sun exposure, we investigated leaf biochemical variations (proline, chlorophyll, and quercetins) and we analyzed with rt-PCR approach the expression of selected genes (VvWRKY47 and VvWRKY39). Results Lower water potential and leaf temperature were recorded in plants subjected to treatments against abiotic stress together with greater chlorophyll a, b, and less quercetin-3-O-glucoside. A down-regulation in VvWRKY47 gene and an up-regulation in VvWRKY39 gene were found. The VvWRKY47 showed interactions from the beginning with the zeolitic treatment. Conclusion The zeolite in our experiment acted as a water flywheel, mitigating the effects of climate change; plant-soil interactions were positively emphasized by clinoptilolite. Finally, results suggest that VvWRKY47 could be a valid candidate in the evaluation of drought and temperature stress in the open-field.

Indirect and direct drivers of floristic condition in a threatened temperate woodland

Almost half of Earth's surface is threatened by agriculture, which has extensively degraded ecosystems and resulted in significant biodiversity loss. Remnant ecosystems in fragmented agricultural landscapes are threatened by past and present grazing and land-clearing. Declines in native diversity are common in these ecosystems, and their restoration is a key conservation goal globally. Understanding the drivers of change in floristic condition, reflecting continuity in floristic composition towards native plant communities, is fundamental to inform effective restoration practice. Previous investigations have demonstrated abiotic and biotic drivers of floristic condition independently. However, few consider the combined influence of these drivers on floristic condition, or the interactions between them, which may mediate indirect effects (e.g. plant-soil interactions). Despite this, ecological interactions may underpin changes in floristic condition, and provide critical insights needed to inform restoration. Here, we use structural equation modelling to disentangle the relationships between plants, soils and grass and litter biomass (leaf litter and fine woody debris) to elucidate the direct and indirect drivers of floristic condition in some of the most degraded landscapes globally: the critically endangered box-gum grassy woodlands in south-eastern Australia. We identify divergent plant-soil interactions between native versus exotic plants to key soil properties including soil nitrate and phosphorus. Specifically, native plants were negatively associated with increasing soil fertility, which favored exotic species. We also found evidence of indirect effects on floristic condition, mediated through interactions between litter biomass, soils and the basal area of overstorey trees. Our findings highlight the major role of soils in shaping floristic condition through direct and indirect pathways, and the role of multivariate interactions in mediating these pathways in a highly degraded, critically endangered ecosystem. Effective restoration must therefore consider the multivariate direct and indirect drivers of ecological condition to maximise positive outcomes in these landscapes and those similar.

Optimized extraction methodology for phenolic compounds in soil and plant tissues: Their implications in plant growth and gall formation

Phenolic compounds, abundant secondary metabolites in plants, profoundly influence soil ecosystems, plant growth, and interactions with herbivores. Phenolic in soil microorganisms have the potential to impact a wide range of activities in plant-soil interactions. However, the existing methods for measuring microbial activity are typically time-consuming, intricate, and expensive. In this study, we propose modifications to the method used for the extraction and quantification of various types of phenolics in soil and plant tissues. There have been substantial advancements in research aimed at extracting, identifying, and quantifying phenolic compounds in the plant and soil samples. This study discusses the use of different methodologies in the analysis of phenolic compounds. In addition, we investigated the effect of phenolics on plant growth and cues in gall-forming under environmental disturbances.•This method is the optimum way to extract phenolic from soil and microbial activity in bulk and rhizosphere soil.•It can be used on any soil type and plant tissue, metabolites extracted from living organisms.

Metabolite Profiling of Urban and Forest Tree Rhizosphere Soil using Analytical Instruments

The rhizosphere is the area of the soil affected by plant roots and plays an important role in plant health, nutrient cycling, and soil structure. This study investigated differences in rhizosphere soil metabolites between trees in urban and forest environments using LC/MS-Q-TOF and GC/MS. Urban environments can cause soil pollution and ecosystem disturbance due to the accumulation of heavy metals and petrochemicals, while forest environments are rich in organic matter and fallen leaves, maintaining a nutrient-rich environment in which various microorganisms coexist. Rhizosphere soil samples were collected from Dankook University (city) and Taejo Mountain (forest) in Cheonan, South Korea, extracted using methanol and chloroform using the Soxhlet extraction method, and then analyzed by LC/MS-Q-TOF and GC/MS. N-Nitrosopyrrolidine, a possible carcinogen from automobile exhaust and industrial activities, has been found in the rhizosphere soil of urban trees. Forest rhizosphere samples showed high concentrations of momilactone A, which is important for plant defense mechanisms. 140 significant metabolites were identified through MPP analysis. Furthermore, GC/MS analysis confirmed that siloxanes and oleamides were predominantly detected in urban and forest samples, respectively. Overall, this study highlights the impact of environmental conditions on rhizosphere soil chemistry and microbial ecosystems and provides insights for urban greening and forest conservation strategies. Comprehensive profiling of rhizosphere metabolites will improve our understanding of plant-soil interactions and contribute to maintaining soil health and plant diversity in diverse ecosystems.