Dissimilatory sulfur oxidation mediated by the microbial sulfur-oxidizing (Sox) multienzyme complex has played a central role in Earth's oxidative sulfur cycle. However, the evolutionary trajectory leading to its current complexity remains poorly understood. Here, we integrated expanded genomic records with geochemical evidence to reconstruct the natural history of the Sox system along a geological timeline. Our analyses traced the origin of the truncated Sox system (SoxABXYZ) prior to the Great Oxidation Event (GOE). This early form was later assembled with reverse dissimilatory sulfite reductases (rDsr), facilitating a primitive pathway for sulfate formation during the anoxic Archean eon. Following the post-GOE atmospheric oxygen rise, the truncated system incorporated SoxCD components, evolving into a more fine-tuned, oxygen-adapted pathway compared to the rDsr-coupled alternative. The subsequent spread of these Sox pathway variants was constrained by the oxygen requirements and phylogenetic backgrounds of their prokaryotic hosts, shaping the modern ecological landscape of microbial sulfur oxidation. The viral recruitment of auxiliary Sox components marked the latest evolutionary events, enabling direct manipulation of sulfur cycling over centuries-to-millennia timescales. Collectively, the reconstructed molecular timeline offers deeper insights into the evolutionary dynamics of the global oxidative sulfur cycle and its billion-year interplay with Earth's changing environments.

Abstract Maintaining microbially mediated phosphorus mobilisation under intensive nitrogen fertilisation is difficult in acidified paddy soils. Using a decade-long field experiment in a rice–oilseed rape rotation, we compared an ordered manure-substitution series, in which manure input increased while mineral nitrogen input decreased, with a mineral nitrogen dose gradient. Increasing mineral nitrogen input was associated with lower diversity and absolute abundance of the phoD-harbouring bacterial guild and a marked shift in community composition. Across the manure-substitution series, soil pH increased from 5.94 to 6.62, potential alkaline phosphatase activity increased by up to 158%, and Olsen-extractable phosphorus increased by up to 182%. The diversity, composition, and absolute abundance of the phoD guild changed progressively across the same series. Distance-based redundancy analysis identified soil pH as the strongest measured marginal correlate of community composition, whereas variation partitioning indicated that the effects of pH, carbon, and phosphorus were largely shared. An exploratory structural equation model was consistent with conditional associations of both community composition and absolute gene abundance with alkaline phosphatase activity, which was in turn associated with Olsen-extractable phosphorus. The highest observed means for gene abundance, grain yield, and grain phosphorus removal occurred in the intermediate manure treatment, whereas treatment-level copper and zinc concentrations increased towards the highest-manure treatment. Together, these findings indicate that manure substitution can counteract mineral nitrogen-associated deterioration of the phoD guild and support microbial phosphorus mobilisation, although the agronomic and metal responses require confirmation across sites and seasons.

Reductive soil disinfestation (RSD) is an efficient and environmentally friendly practice for controlling soil-borne diseases, such as the bacterial wilt in tomatoes caused by Ralstonia solanacearum. The amendment of organic residues is an integral part of RSD; however, how the choice of organic residues affects the disinfestation of R. solanacearum remains poorly understood. Here, we collected organic residues with varying carbon-to-nitrogen ratios (C/N) and assessed their effectiveness in improving soil properties, altering microbial community composition, and suppressing R. solanacearum during RSD. All organic residues significantly increased soil carbon and nitrogen contents while reducing R. solanacearum abundance by approximately two orders of magnitude over 21 days. Organic residues with low C/N, particularly wheat bran and distillers’ grains, showed the greatest effects with RSD in enhancing soil properties or pathogen suppression. These amendments also significantly enriched the ASVs negatively correlated with R. solanacearum (e.g., Xanthomonadaceae, Clostridiaceae), and decreased the ASVs positively correlated with it (mainly Burkholderiaceae). In addition, functional genes associated with carbon and sulfur cycling were enriched under low C/N residues. Mantel’s test showed that R. solanacearum abundance was driven by soil pH, organic residues’ C/N ratios, and the correlated ASVs. In all, our results highlight the value of incorporating low C/N organic residues with RSD to improve soil properties, suppress R. solanacearum, and advance the development of effective soil disinfestation strategies.

Dissolved organic matter (DOM) is a highly active constituent of organic fertilizers, playing a key role in enhancing soil nutrient bioavailability and crop yields. However, the influence of the polar fractions and molecular diversity of organic fertilizer-derived DOM on soil phosphorus (P) mobilization remains insufficiently explored. This study integrated solid-phase extraction, spectroscopy, and mass spectrometry in both field and P sorption experiments to investigate the effects of DOM polar fractions on soil P availability. Long-term inorganic and organic fertilization increased the soil P activation coefficient and P use efficiency by 29 % and 30 %, and maintained crop P uptake and yield despite a 34 % reduction in chemical P input compared to chemical-only fertilization. This effect is significantly correlated to the concentration of hydrophobic neutral (HON) and hydrophobic basic (HOB) fractions. The P sorption experiments further confirmed that the hydrophobic fractions (HON and HOB) more effectively suppressed P sorption compared to hydrophilic and hydrophobic acidic fractions. This inhibition may stem from the competitive interactions at soil P sorption sites and the reduction of soil zeta potential driven by lignin-highly unsaturated and phenolic compounds, characterized as aromaticity values of 0.14-0.36, double-bond equivalents of 6.8-10.9, and hydrogen-to-carbon ratios of 1.0-1.4. In summary, this study highlights the influence of DOM polar fractions and molecular composition on soil P availability, providing valuable direction for developing organic fertilizers designed to promote P use efficiency and agricultural sustainability.

Triadimefon, a representative chiral triazole fungicide, is ubiquitously applied as a racemic mixture and exhibits negative effects on microbiome in agroecosystems. However, its enantioselective effects on soil microbial community structure and assembly processes remain undefined. In this study, we investigated how bacteriome assembly responds to triadimefon at the enantiomeric level. It was found that the R- and S-enantiomers exerted distinct effects on bacterial diversity and community structure. Furthermore, deterministic processes dominated bacterial community assembly under chiral triadimefon. Co-occurrence network analysis revealed a distinct shift in microbial network across the chiral triadimefon treatments, revealing enantiomeric disparity in network organization to different enantiomers. Importantly, we identified 12 and 6 distinct key amplicon sequence variants (ASVs), respectively, selected by R- and S-enantiomers. These stereoselective key taxa are closely associated with bacterial community recombination trajectories. Overall, our research provides novel insights into understanding the enantioselective response of microbiome under chiral triadimefon and ideal targets to manipulate for contaminated situations. Synopsis Soil microbial community assembly exhibited striking differences in response to the R- and S-enantiomers of triadimefon, which are governed by the stereospecific selection imposed on the keystone taxa.

Prolonged continuous cropping of Atractylodes macrocephala usually cause soil-borne diseases such as root rot, resulting in significant yield losses even total crop failure. Burning, fumigation, and microbial inoculant application are commonly used to suppress soil-borne diseases in agricultural systems. However, their effects on plant performance and soil microbial communities in continuously cropped A. macrocephala systems remain poorly understood. We conducted a field experiment with high-throughput amplicon sequencing to examine the effects of burning, soil fumigation, microbial inoculant application, and their combined treatment (burning + fumigation + microbial inoculant application) on the survival rate, yield, and soil microbial communities of continuously cropped A. macrocephala, as well as to identify the key microbial taxa influencing A. macrocephala survival. The results showed that all soil amendment treatments increased A. macrocephala survival rate and yield. Soil fumigation treatment had the strongest effect on plant survival, with a survival rate of 66.9% and a yield of 2533.46 kg·hm-2, representing 89.5% and 157.8% increases, respectively. The combined treatment of soil burning, fumigation, and microbial inoculant application resulted in a survival rate of 61.1% and a yield of 2749.52 kg·hm-2, correspon-ding to 73.1% and 179.8% increases, respectively, and showed the largest yield gain among all treatments. Soil fungal community composition differed significantly among treatments, whereas bacterial community structure exhi-bited comparatively limited variation. Soil fungal communities in the control were dominated by Basidiomycota, whereas Ascomycota predominated in soils subjected to burning, fumigation, microbial inoculant application and the combined treatment. The combined treatment harbored the most connected fungal network, with 14204 edges, and exhibited a smaller decline in network stability following the removal of keystone nodes, indicating enhanced network complexity and robustness. Random forest analysis identified Leptosphaerulina, Saitozyma, Paraboeremia, and Fusarium as the key fungal genera associated with A. macrocephala survival, with their relative abundances being significantly reduced under fumigation and the combined treatments. The survival rate of A. macrocephala was negatively correlated with the relative abundances of Saitozyma (R2=0.32). Together, these findings indicate that soil fumigation and the combined application of soil burning, fumigation, and microbial inoculants can improve the ecological function of continuously cropped soils by restructuring soil microbial communities, enhancing fungal network stability and suppressing putative fungal pathogens, thereby increasing the survival rate and yield of A. macrocephala.

Calcium (Ca) availability is vital for optimal plant growth and immune signaling, yet the underlying mechanisms remain elusive. Here, we reveal that Arabidopsis vacuolar H⁺-pyrophosphatase (AVP1)-regulated cytosolic inorganic pyrophosphate (PPi) homeostasis governs leaf growth by maintaining cellulose synthesis to suppress autoimmune activation upon Ca deficiency. Ca deficiency reduces the AVP1 abundance, while AVP1 eliminates excess cytosolic PPi, which impairs guanosine triphosphate-dependent microtubule assembly and reduces cellulose synthase 3-mediated cellulose synthesis. This cell-wall disruption activates isochorismate synthase 1-mediated salicylic acid production, triggering autoimmune responses and inhibiting new leaf growth. Enhancing PPi hydrolysis genetically improves plant growth tolerance to low Ca availability (low-Ca). The link between Ca-dependent PPi metabolic regulation, autoimmunity, and leaf growth is conserved in tomato, highlighting the broad relevance of AVP1 and PPi homeostasis in plant resilience. Our findings offer potential strategies for improving crop tolerance to nutrient-limited environments.

Calcium (Ca) is an essential mineral nutrient transported in plants predominantly through the apoplastic pathway. While the molecular assembly of the Casparian strip (CS), the critical apoplastic barrier in the root endodermis, has been elucidated significantly over the past decade, the precise mechanisms by which the CS regulates Ca uptake, transport and translocation remain unclear. Building on our previous identification of LOTR1 as a regulator of CS formation, we here establish its genetic interaction with the receptor-like kinase SGN3. We show that LOTR1 promotes CS fusion additively with SGN3 but corrects CS positioning only partially through SGN3-dependent pathways. By analyzing single and double mutants across varying Ca gradients, we uncover a bidirectional gating function of the CS. Specifically, an intact CS is required to retain Ca within the stele under Ca limitation, while simultaneously restricting excessive Ca entry under high-Ca to prevent toxicity in shoots. Moreover, using non-invasive micro-test technology, we reveal that disruption of CS function reduces net Ca2+ influx in both meristematic and mature root zones. Together, these findings demonstrate that the CS is essential for plant adaptation to fluctuating Ca environments by sustaining efficient root Ca uptake and strictly regulating root-to-shoot Ca translocation.

Earthworm gut microbiome can significantly influence soil microbial community and functions. However, how earthworms affect the abundant, intermediate, and rare soil bacterial taxa and subsequently regulate soil multifunctionality remains poorly understood. In this study, we investigated bacteria composition and functional gene traits with and without earthworm addition in low-nutrient soil. Our results show that earthworm addition enhanced soil multifunctionality, including organic carbon, nitrogen, and phosphorus mineralization. Compared to other groups, abundant taxa in earthworm-treated soil exhibited higher 16S rRNA operon copy numbers, copiotroph/oligotroph ratios, niche width, and network efficiency, suggesting a greater competitive capacity for resource acquisition. We identified a core set of persistent abundant taxa genera (11 genera) in earthworm-treated soil, which persisted throughout the incubation period, and were notably dominant among abundant taxa in the earthworm gut (67.1

Soil acidification driven by nitrification threaten agricultural sustainability, yet strategies to concurrently suppress proton generation and immobilize phytotoxic aluminum (Al) remain limited. This study evaluated six amendments, including silicon-calcium-magnesium compounds (SiCaMg), humic acid (HA), biochar (BC), chitosan (CH), cellulose (CE), and sodium lignosulfonate (LNa), for controlling soil acidification, Al phytotoxicity, and nitrification process. Compared to untreated control (CK), LNa increased soil pH by 0.69 units, enhanced exchangeable base cation (EBC) pool by 1.45-fold while reduced exchangeable Al3+ by 36.1 %, outperforming SiCaMg which achieved 0.52 units rise in pH, 0.86-fold increase in EBC but 57.8 % decrease in phytotoxic Al3+. Notably, soil reacidification was retarded by LNa whereas accelerated by SiCaMg. Soil solid-state 27Al nuclear magnetic resonance (NMR) analyses revealed that SiCaMg immobilized Al primarily through co-precipitation, whereas LNa and CH facilitated organic-Al complexation mediated by sulfonic and amino ligands, respectively. Notably, nitrification rate was promoted from 1.48 (CK) to1.86 mg kg- 1 & sdot;d- 1 with SiCaMg, concomitant with the enrichment of ammonia-oxidizing archaea (AOA, Ca. Nitrososphaera) and nitrite-oxidizing bacteria (NOB, Nitrospira). Conversely, nitrification rate was strongly suppressed to 0.34 mg kg- 1 & sdot;d- 1 by LNa, attributable to reductions in both AOA and NOB populations. Whereas HA and BC exerted minimal effects on soil acidity and nitrification, CE unexpectedly activated Al mobility and decoupled nitrification process despite reducing AOA/ NOB abundance. We establish LNa as a uniquely dual-functional inhibitor that mitigates soil acidification through simultaneous Al immobilization and nitrification inhibition. This work advances a "source-process management" paradigm for sustainable agricultural soil remediation.

Root hairs enlarge root surface and facilitate plant exploration for edaphic resources, particularly under nutrient-limiting conditions. While magnesium (Mg) deficiency is known to markedly stimulate root hair development, the underlying molecular mechanisms remain poorly characterised. Here, we elucidate the critical role of SHADE AVOIDANCE 4 (SAV4) in regulating Mg deficiency-induced root hair elongation through modulating epidermal auxin level in Arabidopsis. Root hair elongation under Mg deficiency was significantly suppressed in sav4 mutant, and SAV4 epidermal-specific expression partially rescued its root hair elongation defect. Further analysis revealed that SAV4 expression was upregulated in root tips under Mg deficiency. Attenuated root hair elongation in sav4 mutants is explained by reduced basipetal auxin transport in the root epidermis, caused by an inability to maintain the abundance of the membrane-localised auxin efflux carrier PIN2. The endocytosis of PIN2 is delayed in Arabidopsis roots under Mg deficiency, which is released in sav4 mutant and thus impairs basipetal auxin transport. Our findings establish a molecular framework wherein SAV4-mediated dynamics of PIN2 at the epidermal membrane under Mg deficiency ensures proper basipetal auxin transport, thereby facilitating root hair elongation.

Root hairs are crucial for nutrient acquisition and exhibit high developmental plasticity in response to external nutrient availability. However, the specific root hair responses and mechanisms that integrate external nitrogen (N)-limitation signals into the root hair development remain poorly understood. This study revealed that under N deficiency, a set of genes associated with root hair development and ethylene responses was markedly upregulated in Arabidopsis roots. On a molecular level, the transcriptional activity of ETHYLENE INSENSITIVE 3 (EIN3), a master transcription factor of ethylene signaling, was augmented in the root vascular tissues under N deficiency, as shown by the 5×EBS:GUS staining. Further research using the ethylene-insensitive mutant ein3-1eil1-1 exhibited significantly reduced root hair length under low-N conditions. The inhibitory effect was further confirmed by ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG). We also found that low nitrate significantly enriched ROS-related metabolic processes. Subsequent functional analyses revealed that the resulted ROS is specifically required for root hair elongation. Crucially, we demonstrate that ROS accumulation is required for the ethylene-dependent growth of root hairs under N deficiency. Taken together, these results suggest that N deficiency triggers a signaling cascade involving both ethylene and ROS to regulate root hair elongation, thereby enhancing the plant's capacity for nutrient acquisition.

Beneficial microbiomes significantly modulate root hair morphogenesis, yet the underlying signalling pathways remain unclear. Through comprehensive phenotypic analysis, we demonstrated that Azospirillum brasilense, a well-known plant-growth-promoting rhizobacteria (PGPR), promotes root hair development by prolonging the elongation period. The promotion of root hair growth by A. brasilense is attributed to increased auxin accumulation in root apices and enhanced shootward transport from the root tip, which is mediated by the accumulation of the auxin importer auxin transporter protein 1 (AUX1) in the lateral root cap and the overlying epidermis. Chemical or genetic disruption of auxin signalling abolished bacteria-induced root hair responses. Furthermore, A. brasilense upregulated several root hair-related basic helix-loop-helix family transcription factors, including root hair defective 6 (RHD6) and RHD6-LIKE 1 (RSL1), which control root hair development through RSL4. Morphological analysis revealed that while the rsl2rsl4 double mutant remained hairless after inoculation, A. brasilense successfully rescued root hair growth in rhd6rsl1. These findings suggest that A. brasilense can bypass RHD6 to activate RSL4, which then drives root hair development dependent on ROS. Collectively, our study uncovers the core signalling components modulated by A. brasilense to fine-tune root hair responses.

Chemical phosphorus (P) fertilizers generally exhibit low utilization efficiency. The combined application of chemical fertilizers and organic manure is considered an effective strategy to improve soil P availability and crop yields. However, the long-term effects of partially substituting chemical P fertilizer with organic manure on P fertilizer efficiency and crop yield remain poorly understood. To address this, a 5-year field experiment was conducted in a double-rice cropping system to evaluate the impact of substituting chemical P fertilizer with organic manure on rice yield, apparent P recovery (APR), and soil P availability. Our results showed that compared to conventional chemical fertilization (NPK), substituting 20% of P with organic manure, while maintaining the same total N, P, and K inputs (CM(P)), increased grain yield by 4.59% and soil Olsen-P content by 25.48%. In contrast, 20% swine manure substitution with reduced P input (CM(-P)) sustained rice yield and soil Olsen-P levels comparable to NPK. Additionally, treatments CM(P) and CM(-P) increased APR by 59.91% and 82.50%, respectively, and the P activation coefficient by 139.13% and 171.74%. Rice yield and APR were significantly positively correlated with soil Olsen-P, suggesting that manure-induced improvements in soil P availability promoted both rice yield and APR. Overall, our study demonstrates that partial substitution of chemical P fertilizer with organic manure, particularly with reduced P input, is a sustainable fertilization strategy for enhancing P fertilizer efficiency and maintaining crop yields.

Soil carbon (C) cycling under anoxic conditions is mechanistically linked to dissimilatory iron (Fe) reduction, potentially influenced by exogenous dissolved organic matter (DOM). However, the impact of complex exogenous DOM on soil microbial activity and C-Fe coupling in paddy soils remains underexplored. With a 100-day microcosm experiment, we found that biochar-DOM significantly promoted Fe reduction and accelerated CH4 and CO2 emissions, and manure-DOM increased soil CO2 emissions. These effects may be caused by the following mechanisms: DOM molecules with high aromaticity and high double bond equivalence (DBE), including lignins-polyphenols, lignins-polycyclic aromatics, and condensed aromatics-polycyclic aromatics, promoted soil Fe reduction and CH4 emissions with enrichment of soil Fe-reducing bacteria, r-strategists, and reduction of methanotrophs at the early stage of incubation. Conversely, DOM with low aromaticity, low DBE, and high H/C enhanced CO2 emissions with the enhancement of recalcitrant C degradation and CH4 oxidation at the late stage of incubation. In conclusion, our study highlights the importance of the molecular composition of organic amendment-derived DOM in regulating soil Fe reduction and greenhouse gas emissions. The findings offer novel insights into the effective utilization of agricultural resources and the potential mitigation of greenhouse gas production and emissions.

Antibiotic resistance genes (ARGs) naturally serve ecological and adaptive functions in microorganisms, yet human activities have disrupted this balance, accelerating their enrichment and spread in the soil–plant system. As a key ARG transmission interface across One Health sectors, the soil–plant system warrants greater attention. This review synthesizes emerging evidence on the distribution and transmission of resistomes in the rhizosphere, phyllosphere, and endosphere, revealing the potential risk of soil–plant ARGs to human, animal, and plant health. However, major gaps remain, particularly in horizontal and vertical ARG transmission associated within the plant endosphere and across plant generations. Moreover, we summarize key factors shaping soil–plant ARG dynamics, including soil conditions, plant evolution and traits, and anthropogenic influences. Among these, climate change emerges as a global, long-term, and largely irreversible driver, altering soil properties, plant physiology, and microbial activity through drastic environmental shifts. We discuss the risks of climate-driven ARG dissemination and its broader ecological and agricultural implications. Addressing these challenges requires advanced monitoring methods, integrated data sources, and policy innovations. In this review, we highlight climate change as an emerging driver of ARG selection and dissemination, emphasizing its impact on soil–plant resistome and the need for future One Health research on climate-driven resistome shifts.

Lipids, as key components of biological membranes, play vital roles in sensing and initiating plant responses to various abiotic stresses. Here, the alteration of membrane fatty acids in wheat roots under Al stress was investigated using two genotypes differing in Al tolerance, and the role of linoleic acid in Al tolerance was comprehensively explored. Significant differences in the fatty acid profiles were observed, with increased linoleic acid accumulation in the Al-tolerant genotype. Supplementation with linoleic acid enhanced fatty acid synthesis, reduced membrane lipid saturation, improved membrane fluidity, and alleviated root growth inhibition. Wheat seedlings treated with linoleic acid exhibited a reduction in lipid peroxidation, as evidenced by decreased levels of malondialdehyde and lipid hydroperoxides. Furthermore, the application of linoleic acid increased the total contents and reduced forms of ascorbic acid (AsA) and glutathione (GSH), thereby restoring the cellular redox balance in wheat roots under Al stress. The elevated levels of AsA and GSH maintained by linoleic acid, can be attributed to the high efficiency of the AsA-GSH cycle, as linoleic acid enhanced the activities of the antioxidant enzymes involved. These results suggest that linoleic acid enhances wheat Al tolerance by maintaining both fatty acid synthesis and the levels of unsaturated fatty acids, as well as protecting membrane lipids from peroxidation by reactive oxygen species through the regulation of the AsA-GSH cycle.

While iron (Fe) is essential for life and plays important roles for almost all growth related processes, it can trigger cell death in both animals and plants. However, the underlying mechanisms for Fe-induced cell death in plants remain largely unknown. S-nitrosoglutathione reductase (GSNOR) has previously been reported to regulate nitric oxide homeostasis to prevent Fe-induced cell death within root meristems. Here, we found that in the absence of GSNOR, exposure to high Fe treatment results in DNA damage-dependent cell death specifically in vascular stem cells in root meristems within 48 h. Through a series of time-course transcriptomic analyses, we unveil that in the absence of GSNOR, mitochondrial dysfunction emerges as the most prominent response to high Fe treatment. Consistently, the application of mitochondrial respiratory inhibitors leads to stem cell death in root meristems, and pharmacological blockage of the voltage-dependent anion channel that is responsible for the release of mitochondrial-derived molecules into the cytosol or genetic changes that abolish the ANAC017- and ANAC013-mediated mitochondrial retrograde signaling effectively eliminate Fe-induced stem cell death in gsnor root meristems. We further identify the nuclear transcription factor ANAC044 as a mediator of this mitochondrial retrograde signaling. Disruption of ANAC044 completely abolishes the GSNOR-dependent, Fe-induced stem cell death in root meristems, while ectopic expression of ANAC044 causes severe root stem cell death. Collectively, our findings reveal a mechanism responsible for initiating Fe-induced stem cell death in the root meristem, which is the ANAC044-mediated GSNOR-regulated mitochondrial stress signaling pathway.

The cycling of soil phosphorus (P) is inherently linked with soil organic carbon-iron (C-Fe) cycling, yet empirical integration of these processes within paddy soils remains scarce. In this study, we conducted a microcosm experiment using paddy soils subjected to six distinct fertilization regimes involving varying P inputs for five years. In addition to evaluating P activation under reflooding conditions, we assessed the Fe reduction process and characterized the properties of dissolved organic matter (DOM) at the molecular level using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), alongside profiling the composition of soil microbial communities with high-throughput sequencing. Our findings revealed that after 25 days of reflooding, soil Olsen-P content increased by an average of 73% compared to its initial state, showing a strong correlation with the Fe reduction process. Specifically, treatments involving pig manure application exhibited higher Fe reduction rates and enhanced P activation, highlighting the role of organic matter in facilitating Fe reduction. Investigations on the relative abundance of typical iron-reducing microbes further supported their importance in P activation, but the rate of iron reduction is limited by soil organic matter content. Delving deeper into DOM properties, soil DOM composition profiling and network analysis suggested that high-molecular-weight DOM, particularly lignins, served as the primary resources driving Fe reduction by iron-reducing microbes, consequently promoting Fe reduction and P release. Taken together, our study assembled the C-Fe-P cycling dynamics in paddy soils, emphasizing the pivotal role of microbial-driven Fe reduction facilitated by soil DOM in P availability and subsequently sustainable agricultural practices.

Calcium (Ca), an essential macronutrient, is crucial for the growth of young plant tissues, including the formation of lateral roots (LRs) that originate from pericycle cells in the inner root. The Casparian strip (CS) serves as an apoplastic barrier in the root endodermis, optimizing nutrient transport and facilitating plant adaptation to various environments. This study demonstrates that the integrity of the CS regulates local Ca-dependent LR emergence by controlling the lignification of the overlying endodermal cells in Arabidopsis. In mutants with disrupted CS integrity and compensatory lignin deposition, plants require sufficient Ca to maintain auxin gradients and the morphology of LR primordia, thereby promoting LR primordia through the endodermis. Both piperonylic acid treatment and genetic evidence indicate that excessive lignification of the overlying endodermal cells significantly delays LR emergence under low-Ca conditions compared with sufficient Ca. The receptor-like kinase SGN3/GSO1 mediates this excessive lignification. Importantly, the function of the CS in LR emergence is independent of Ca translocation from roots to shoots and, consequently, shoot growth dynamics. Overall, our study highlights the direct involvement of CS integrity in modulating Ca-dependent LR emergence by controlling cell wall stiffness through the lignification of overlying endodermal cells.