Plant and Soil

Nitrogen (N) and phosphorus (P) deficiencies can significantly reduce crop yield. Despite their importance, the impacts of N and P deficiencies under field conditions on cereal roots, particularly winter rye, remain poorly understood. This study investigates the effects of N and P deficiencies on winter rye growth and root architecture under field conditions. A sampling campaign was conducted during the 2022 season at the long-term fertilizer experiment Dikopshof, Germany. Four fertilizer treatments were chosen: (1) fully fertilized with manure (NPKCa+m+s), (2) fully fertilized without manure (NPKCa), (3) N omitted (_PKCa), and (4) P omitted (N_KCa). Shoot biomass was assessed at five growth stages, alongside with topsoil root biomass, number of nodal roots and tillers, and root angle. The results showed that shoot and root biomass were highest in the NPKCa+m+s treatment and lowest under N omission. Although the treatment ranking of root traits varied between dates, a trend for an enhanced number of roots in the N and P omission treatments was observed around flowering. P omission fostered an increased number of tillers and N omission caused steeper root angles compared to other treatments. These findings demonstrate the strong impact of the environment and development stage on root phenotypic plasticity.

AbstractEnhanced weathering (EW) of silicate minerals has emerged as a promising carbon dioxide removal (CDR) strategy, with potential benefits for soil fertility and crop performance. However, the soil processes that determine these co-benefits remain poorly constrained. In particular, interactions between basalt amendments and soil biota such as arbuscular mycorrhizal fungi (AMF) may influence nutrient mobilization and plant uptake, but these effects have rarely been quantified. In a 113-day mesocosm experiment with Zea mays using a Belgian, sandy loam soil, we investigated the effect of basalt and AMF inoculation on soil properties, nutrient and heavy metal availability, and crop yield and quality. We also assessed potential AMF-driven bio-weathering via cation mass balance and pore water dissolved inorganic carbon (DIC), pH, and alkalinity measurements. Basalt application, but not AMF, improved soil pH, cation exchange capacity, base saturation, and generally increased exchangeable Ca and Mg, whereas most other nutrients in the pore water remained unaffected. Crop yield and quality were largely unaltered by basalt or AMF, except for an increase in plant Mg with basalt application. Moreover, heavy metal availability and plant uptake were also generally unaffected, with the notable exception of soil pore water and corn Ni, which increased with basalt. These results suggest that risk for heavy metal contamination is not generic but may arise under specific environmental conditions. Finally, despite a synergistic effect of basalt and AMF on pore water DIC, we found no indication that AMF enhanced basalt weathering rates. Overall, AMF had limited influence on soil fertility indicators and crop performance. Basalt application improved key soil chemical indicators and increased the exchangeable fractions of Ca and Mg, demonstrating its role as a soil improver. Unlike several studies conducted in more acidic soils, these chemical enhancements did not increase maize growth here, indicating that the agronomic benefits of basalt are context-dependent.

Crop root systems develop in biologically complex soils where beneficial symbionts and pathogenic organisms can jointly influence root architecture and, consequently, belowground function. In this work, we used X-ray computed tomography (CT) to assess how colonisation by the arbuscular mycorrhizal fungus Rhizophagus irregularis (AMF) and infection by the potato cyst nematode Globodera pallida (PCN) influence root system architecture in soil-grown tomato and potato plants. Root architectural traits, including root volume and root surface area, were quantified non-destructively from intact root systems to evaluate the individual and combined effects of AMF colonisation and PCN infection over time. AMF inoculation increased root volume and surface area, whereas PCN infection caused pronounced reductions in these traits, particularly during early development. AMF-associated increases in root system size were maintained in both PCN-free and PCN-infected plants, indicating largely additive effects of beneficial and pathogenic soil biota on root architectural outcomes. These findings show that soil organisms can independently reshape crop root development in ways likely to influence soil exploration and resource acquisition under biologically complex conditions. More broadly, the study highlights the value of X-ray CT as a non-destructive approach for linking belowground biotic interactions with functionally relevant root traits in sustainable agroecosystems.

Growing evidence suggests that soil microbes can improve plant fitness under drought. However, in potato, the worlds most important non-cereal crop, the role of the rhizosphere microbiome under drought has been poorly studied. Using a cultivation independent metabarcoding approach, we examined the rhizosphere microbiome of two potato cultivars with different drought tolerance as a function of water regime (continuous versus reduced watering) and manipulation of soil microbial diversity (i.e., natural (NSM), vs. disturbed (DSM) soil microbiome). Water regime and soil pre-treatment showed a significant interaction with bacterial community composition of the drought-sensitive (HERBST) but not the drought-resistant cultivar (MONI). Depending on the cultivar, different taxa responded to reduced watering. Under NSM conditions, these were mostly rhizobiales order representative in MONI, and Streptomyces, Glycomyces, Marmoricola, Aeromicrobium, Mycobacterium, amongst Actinobacteriota, and the root endophytic fungus Falciphora in HERBST. Under DSM conditions and reduced watering, Bradyrhizobium, Ammoniphilus, Symbiobacterium and unclassified Hydrogenedensaceae responded in the rhizosphere of MONI compared to the continuous, while in HERBST, fewer taxa of Actinobacteriota and no fungi responded to reduced vs. continuous watering. Overall, our results indicate a strong cultivar specific relationship between potato and their associated rhizosphere microbiomes under reduced soil moisture.

The emergence of the Guava Root-Knot Nematode (Meloidogyne enterolobii) poses a significant threat to tomato yields globally. This study aimed to evaluate the impact of collagen and chitin soil amendments on soil microbial composition and function (fungal and bacterial communities), and their effects on tomato plant health and M. enterolobii infection under standard (5,000 eggs plant-1) and high (50,000 eggs plant-1) inoculum pressure. Conducted in a greenhouse setting, the study investigated the effectiveness of these amendments in nurturing beneficial microbial communities across both native and agricultural soils. Both collagen and chitin were effective in reducing nematode egg counts up to 66% and 84% under standard and high inoculum pressure, respectively and enhance plant health parameters (biomass and chlorophyll content). Moreover, a microbiome shift led to an increase in bacterial (Kitasatospora, Bacillus, and Streptomyces) and fungal (Phialemonium) genera, known for their chitinase, collagenase, and plant-parasitic nematode control. Among the microbes, Streptomyces spp. were found among the core microbiome and associated with a lower disease incidence assessed through a phenotype-OTU network analysis (PhONA). Under standard inoculum a higher metabolite expression was observed with the amino acid class being the majority among the metabolite groups. The findings highlight the potential of collagen and chitin to mitigate Meloidogyne enterolobii infection by fostering beneficial soil microbial communities.

Global climate change stressors are altering soil function and reducing crop yields, yet the role of soil microbial legacies in shaping plant stress responses remains poorly understood. Here, we tested how long-term farming (organic vs conventional) and climate (ambient vs future) histories of soil microbiomes influence wheat performance under drought. Soil samples were collected from long-term experimental plots of the Global Change Experimental Facility (GCEF, Germany) and used to extract microbial communities, which were then used to inoculate sterilized potting soil in which two wheat cultivars, drought-sensitive Nordkap and drought-tolerant SU Fiete, were grown under controlled greenhouse drought. Our results showed that microbial inoculation enhanced germination relative to non-inoculated, with conventional-ambient microbiomes most strongly promoting emergence, while organic-future microbiomes suppressed seed germination. Under drought, aboveground fresh biomass and dry weight content diverged by interaction between cultivar and microbial legacy in such a way that Nordkap performed best with future-climate microbiomes, whereas SU Fiete benefited from ambient-climate microbiomes. The rhizosphere of plants inoculated with organic-derived microbes harbored a larger unique ASVs, with 442 bacterial and 70 fungal ASVs, compared with 381 bacterial and 48 fungal ASVs unique to conventional-derived microbes. We further showed that rhizosphere bacterial communities were influenced by complex interactions between microbial history (farming and climate), cultivar, and water stress, while fungal communities tracked only farming history, with organic legacies buffering fungal diversity under drought. Together, these results demonstrate that soil microbiomes retain the imprint of past management and climate, and that these legacies can either buffer or exacerbate plant stress responses depending on host genotype.

Similar to the human gut microbiome, diverse microbes colonize the plant rhizosphere, and an imbalance of this microbial community, known as dysbiosis, may negatively impact plant health. This study aimed to investigate the influence of rhizosphere dysbiosis on above-ground plant health using tomato plants (Solanum lycopersicum L.) and the foliar bacterial spot pathogen Xanthomonas perforans as model organisms. Four-week-old tomato plants rhizospheres were treated with streptomycin (0.6 g x L-1), or water (negative control) and spray-inoculated with X. perforans (105 cells x mL-1) after 24 h. Half of the plants treated with streptomycin and X. perforans received soil microbiome transplants (SMT) from uninfected plant donors 48 h after streptomycin application. Streptomycin-treated plants showed a 26% increase in disease severity compared to plants that received no antibiotic, while plants that received the SMT had an intermediate level of disease severity. Antibiotic-treated plants showed a reduced abundance of rhizobacterial taxa like Cyanobacteria from the genus Cylindrospermum as well as down-regulation of genes related to plant primary and secondary metabolism and up-regulation of plant defense genes associated with induced systemic resistance (ISR). This study highlights the crucial role of beneficial rhizosphere microbes in disease resistance, even to foliar pathogens.

IntroductionSeveral Desmodium spp. are used as intercrops in push-pull pest management systems to repel insect herbivores. In addition, Desmodium suppresses the parasitic weed Striga, and diversifies the soil microbiome with negative impacts on fungi. We investigated the impact of a 2-year cropping of five Desmodium species on soil microbiome populations. MethodologyTotal DNA was obtained from root zone soil samples collected from a two-years-old common garden experiment with replicated plots of five Desmodium spp. at the international centre for insect physiology and ecology (ICIPE), Mbita, Kenya. Subsequently, 16S and ITS DNA sequencing were performed and the data was analysed by using QIIME2 and Calypso. ResultsOur findings show significant differences in composition and abundance of specific microbial taxa among the Desmodium plots and the bulk soil, with a stronger shift observed for fungal community profiles than bacteria. There was, however, no significant difference in overall diversity, richness and evenness of microbial communities among the Desmodium plots and the bulk soil. Similarly, beta diversity analysis did not reveal a significant association of variation to specific Desmodium spp. plots. Discussion and conclusionThis is the first study to compare impact and association of whole soil microbiomes to different Desmodium species. Whereas long-term Desmodium cropping clearly shifts whole microbiome communities, no significant difference in overall diversity and richness of microbial populations was observed among the studied plots. However, there was a divergence of individual taxa reflected on their increased abundance in association to specific Desmodium spp., pointing towards potential impact on ecosystem services. These findings indicate that significant shifts in whole microbial populations due to Desmodium spp. and thus potentially provision of associated ecosystem services require longer cultivation periods to solidify. Future studies should focus on techniques that monitor real-time changes in microbial populations such as RNA-seq to ascertain live and dead microbes, and thus infer ecological services.

Grasslands, as one of the most important terrestrial ecosystems globally, have root functional traits that serve as key indicators of plant responses to environmental changes and hold significant ecological importance. To reveal the current status, research hotspots, and frontier trends in the field of grassland root functional traits, this study analyzed relevant literature from the Web of Science Core Collection database between 2000 and 2025. It employs bibliometric methods and utilizes visualization tools such as CiteSpace for a systematic analysis. The results indicate that research in this field has been continuously increasing since 2000, reflecting a growing research interest. China, the United States, and Germany are the leading countries in terms of publication output. However, collaboration networks among authors, institutions, and countries are still not tight enough to form a truly global cooperative network. Co-occurrence analysis of keywords and literature clustering reveal that the research hotspots in this field are mainly concentrated in six directions: multidimensional characteristics of root functional traits, interactions between root functional traits and climate change, synergistic effects of root functional traits and soil microorganisms, responses of root functional traits to land-use changes, coupling of root functional traits with ecosystem functions, and applications of root functional traits in agriculture and ecological restoration. Future research should focus on promoting innovation and standardization of research methods, conducting long-term monitoring, deeply exploring the mechanisms of root-microbe interactions, implementing cross-scale integrative research and model construction, and building international collaborative networks.

Decomposition of organic matter is a key process in soils contributing to carbon and nutrient cycling. To identify management strategies for agroecosystems that reduce nutrient losses while maximizing plant growth, it is important to understand which parameters determine decomposition rates. This study therefore investigated how the presence of winter wheat (Triticum aestivum var. Asory) affects decomposition in a controlled Ecotron setup with two soil types with varying organic matter content across three simulated climates (2013, 2068, 2085). Using the tea bag index, interstitial soil pore water analyses, microbial biomass quantification, bacterial and fungal gene abundance, and soil respiration measurements, we tested the hypotheses that plant exudates would enhance decomposition rate and microbial biomass, while plant nitrogen uptake would deplete soil nitrate, potentially mitigated by fertilization. Contrary to expectations, decomposition rates were lower in planted than in unplanted soils, suggesting resource competition between plants and microbes. No significant differences were observed in microbial biomass or respiration due to plant presence, and fertilization effects on nitrate or microbial mineralization were undetectable, likely due to rapid turnover of organic molecules including uptake by plants and microbes. Mechanistically, fungi and soil humidity were more important for decomposition than bacteria or temperature. The findings corroborate climate impacts on decomposition but also indicate microbial resilience and highlight the potential of management strategies like cover crops, adjusted planting dates and crop residual management which can contribute to healthy soils by sustaining carbon and nutrient cycling.

Vinasse is a by-product with a key role in the circular economy. In this work, we analyze sugarcane vinasse as culture medium for obtaining single and mixed inoculants. Trichoderma harzianum was cultured in single and sequential co-culture with Pseudomonas capeferrum or Rhizobium sp. Fungal biomass was higher in vinasse than in a laboratory medium. Residual vinasses presented almost neutral pH and lower conductivities and toxicity than raw vinasse. Fertigation with residual vinasses improves characteristics of soil evidenced in the total N, cation exchange capacity, urease and acid phosphatase, and the microbial metabolic diversity, in comparison to raw vinasse. The evaluation of the treatment indicates that vinasse is suitable for the production of inoculants containing T. harzianum and that the co-culture with P. capeferrum improves the characteristics of the residual vinasse in comparison to Rhizobium sp. Obtaining this valuable biomass in vinasse is relevant for the circular and green economy.

Arbuscular mycorrhizal fungi, classified in the subphylum Glomeromycotina, are obligate symbionts that depend on photosynthetic products from plants. There is substantial evidence that AMF support plant and crop growth in natural and agricultural ecosystems. Fine root endophytes (FRE) also co-occur in plant roots with AMF in all but tropical environments. However, their presence remains poorly recognised, and their lifestyle and functionality remain largely unknown. Our analysis demonstrates that, in contrast to AMF, FRE colonise plants during the winter season, when photosynthesis is more challenging. It is also noteworthy that FRE was unable to colonise the roots of spring-sown crops. The results of our laboratory pot experiments demonstrated that low temperatures are not sufficient for FRE colonisation. Furthermore, we observed that FRE, in contrast to AMF, exhibited increased colonisation in soils containing metabolically inactive plants. Our results suggest that FRE does not contribute to the increase of ecosystem biomass through direct photosynthesis in summer, but may play an overlooked role in the formation of mycorrhiza-based soil ecosystems in winter. However, this winter ecosystem can be disrupted by conventional bare fallow management of the field, interrupting the annual cycle.

Anthropogenic disturbances to nitrogen (N) cycling, particularly through agricultural N use, have intensified nitrous oxide (N2O) emissions. Developing wheat lines with biological nitrification inhibition (BNI) is a promising strategy to reduce such emissions. However, the effectiveness of BNI depends not only on plant characteristics, but also on how they interact with environmental factors such as soil pH and elevated atmospheric CO2 (eCO2). This study evaluated the response of a BNI-capable wheat line (Triticum aestivum cv. ROELFS) to eCO2 under contrasting soil pH during the 30 days following ammonium fertilization. Two wheat lines (ROELFS-Control and ROELFS-BNI) were grown under ambient (400 ppm) and elevated (800 ppm) CO2 in acidic (pH 5.3) and alkaline (pH 8.8) soils. N2O emissions, nitrifying and denitrifying microbial communities, and soil chemical properties were monitored to assess plant-soil-microbe interactions. ROELFS-BNI consistently reduced N2O emissions under all conditions by reducing archaeal (Nitrososphaeraceae) and bacterial nitrifiers (Nitrosomonadaceae, Nitrospiraceae) without major shifts in overall microbial composition, indicating high specificity of BNI exudates. Elevated CO2 effects on N2O emissions were pH-dependent. In acidic soil, eCO2 increased emissions in ROELFS-Control but not in ROELFS-BNI, likely due to the enrichment of complete denitrifiers (e.g. Rhodanobacteraceae). However, in alkaline soil, eCO2 reduced N2O emissions in both Control and BNI lines, especially the latter, which was associated with a higher abundance of N2O-reducing denitrifiers (e.g. Burkholderiaceae). This study highlights the potential of ROELFS-BNI wheat as a sustainable practice to mitigate N pollution adaptable to diverse soils and predicted CO2 atmospheric conditions.

Soil microorganisms play a vital role in the regulation of the transformation and cycle of soil nutrients, thereby improving soil fertility and crop productivity. These microbes, associated with plants, contribute significantly to plant growth and development by improving nutrient cycling and crop productivity by improving soil fertility. This systematic review aims to assess the impact of microbial activity on nutrient cycle and transformation, which includes soil fertility and crop productivity improvement. The PRISMA flow methodology systematically included articles from various geographic regions. Through analyzing 120 articles, this review sought to address the question at hand. Among the articles analyzed, 31.4% indicate that soil microbial activity directly regulates nutrient cycling, while 68.6% suggest that microbial activity enhances soil fertility and crop productivity. The systematic review concludes that microbial activity has a significant effect on nutrient cycle and transformation, as well as on improving soil fertility and crop productivity. Farmers, policymakers, and experts are encouraged to manage soil microorganisms to regulate nutrient cycling, directly influencing soil fertility and crop productivity, thus promoting sustainable agricultural development.

Soil alkalinity severely limits legume growth, but the role of Bacillus subtilis in alkaline stress tolerance remains unclear in garden pea. We found that multiple garden pea genotypes inoculated with B. subtilis under alkaline stress showed host-specific improvements in growth parameters. Mechanistic analysis conducted on Sugar Snap showed improved nodulation, mineral status, and photosystem efficiency, while split-root assays revealed that B. subtilis triggered systemic signaling underlying alkaline tolerance. Further, FeEDDHA partially reduced alkaline stress symptoms but did not fully restore nodulation. In contrast, B. subtilis enhanced siderophore availability and improved nodulation, leading to stronger symbiotic recovery than inorganic Fe alone. This indicates that nodulation recovery is driven primarily by B. subtilis-mediated stimulation of Rhizobium leguminosarum, not by Fe availability alone. This is further supported by in vitro co-culture experiments that showed increased growth of both R. leguminosarum and B. subtilis, pointing to their complementary interactions that promote mutual fitness under alkaline stress. RNA-seq analysis identified 958 upregulated and 1,134 downregulated genes in roots inoculated with B. subtilis under alkaline conditions. The upregulated genes were mostly involved in the sugar-mediated symbiotic association (SWEET and GLUT), pH homeostasis (cation/H+ exchanger and ATPase), and nutrient assimilation (Ammonium transporter and Zn/Fe permease). Furthermore, B. subtilis reshaped the rhizosphere by restoring microbial community structure and enriching beneficial taxa such as Pseudomonas, Pseudorhizobium, and Chaetomium, which may act as helper microbes to promote pea survival under alkalinity. Taken together, microbial interventions such as B. subtilis offer an effective strategy to boost legume tolerance to alkaline soils.

O_LIIn the absence of chemical control with its negative side effects, fungal pathogens can cause large yield losses, requiring us to develop agroecosystems that are inherently disease resistant. Grassland biodiversity experiments often find plant species diversity to reduce pathogen pressure, but whether incorporating high biodiversity levels in agricultural fields have similar effects remains largely unknown. C_LIO_LIWe tested if undersown plant species diversity could reduce barley disease, and whether the effect was mediated through above- or belowground mechanisms, by combining an agricultural field trial with a soil transplant experiment. C_LIO_LIAs predicted, barley disease decreased in the presence of undersown plants. Undersown species richness had no effect, but their abundance led to early season disease reduction. Aboveground mechanisms underpinned this disease reduction. Barley yield slightly decreased with increasing undersown species richness, and undersown species varied in their impact on yield. C_LIO_LIWe identified two undersown species with similar functional traits that contributed most to disease reduction and had the potential to increase barley yield. Furthermore, our results indicate that aboveground mechanisms caused this. We show that agroecosystem functioning can be improved without trade-offs on yield by targeted selection of undersown species. C_LI

Empirical data is key to anticipate the impact of climate change on cropping systems and develop land management strategies that are sustainable while ensuring food security. Here, the combined effects of projected increases in temperature, atmospheric CO2-concentrations, solar irradiation and altered precipitation patterns on winter wheat cropping systems were investigated using an Ecotron. Experimental plant-soil systems were subjected to three different climatic conditions representing a gradient of ongoing climate change implementing the weather patterns of the years 2013, 2068, and 2085 respectively. The wheat plants were grown in two differentially manged agricultural soil types: one with long-term low organic matter (OM) inputs and the other one with long-term high OM inputs. In the low OM system, the risk for plant diseases and nitrate leaching was increased, but it outperformed the high OM system with higher yields and lower CO2-emissions. Developing high-yielding cropping systems leveraging the CO2-fertilisation effect without sacrificing environmental health will therefore require further refined of management practices to improve nutrient cycling and reduce greenhouse gas emissions. One possibility is adapting crop rotations and cover crops to the shorter wheat cycle observed in the future climates to replenish soil nutrients and break disease cycles. Further, in both here studied soil types the wheat plants developed natural coping mechanisms against environmental stressors, such as enhanced root growth and increased levels of proline and silicon. Unravelling the molecular mechanisms that trigger such inherent plant defences is a further interesting target for breeding future crops. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=177 HEIGHT=200 SRC="FIGDIR/small/626142v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@fefc32org.highwire.dtl.DTLVardef@5f6757org.highwire.dtl.DTLVardef@1799ca4org.highwire.dtl.DTLVardef@11aec5c_HPS_FORMAT_FIGEXP M_FIG C_FIG

O_LIPlants accommodate diverse microbial communities (microbiomes), which can change dynamically during plant adaptation to varying environmental conditions. However, the direction of these changes and the underlying mechanisms driving them, particularly in crops adapting to the field conditions, remain poorly understood. C_LIO_LIWe investigate the root-associated microbiome of rice (Oryza sativa L.) using 16S rRNA gene amplicon and metagenome sequencing, across four consecutive cultivation seasons in a high-yield, non-fertilized, and pesticide-free paddy field, compared to a neighboring fertilized and pesticide-treated field. C_LIO_LIOur findings reveal that root microbial community shifts and diverges based on soil fertilization status and plant developmental stages. Notably, nitrogen-fixing bacteria such as Telmatospirillum, Bradyrhizobium and Rhizomicrobium were over-represented in rice grown in the non-fertilized field, implying that the assembly of these microbes supports rice adaptation to nutrient-deficient environments. C_LIO_LIA machine learning model trained on the microbiome data successfully predicted soil fertilization status, highlighting the potential of root microbiome analysis in forecasting soil nutrition levels. Additionally, we observed significant changes in the root microbiome of ccamk mutants, which lack a master regulator of mycorrhizal symbiosis, under laboratory conditions but not in the field, suggesting a condition-dependent role for CCaMK in establishing microbiomes in paddy rice. C_LI

Boron (B) is indispensable for plant growth and has been reported in the mitigation of aluminum (Al) toxicity in different plants. This study unraveled the efficacy of B in reducing the toxicity of Al to trifoliate orange seedlings in a hydroponic experiment. In the current study, B supply had a positive effect on root length and plant growth-related parameters, and attenuated Al-induced inhibition of plasma membrane H+-ATPase activity. The results of XPS and SEM-EDS revealed that B reduces the Al accumulation in root cell wall (CW), especially acts on pectin fractions (alkali-soluble pectin), accompanied by suppressing the pectin synthesis, inhibiting pectin methylesterase (PME) activity and PME expression. Furthermore, B application inhibits NRAT1 expression while increases ALS1 expression, which are responsible for restraining Al transport from external cells to the cytoplasm and accelerating Al divert to vacuoles, and the results can be further demonstrated by TEM-EDS analysis. Taken together, our results indicated that B mainly promotes the efflux of H+ by regulating the plasma membrane H+-ATPase activity, futhur reduce the demethylation of pectin to weaken Al binding ability to carboxyl. More importantly, B alleviated some of the toxic effects of Al by decreasing the deposition of Al in cytoplasm and compartmentalizes Al into vacuoles. One-sentence summaryBoron can reduce the binding amount of carboxyl group to Al in pectin, decreasing the deposition of Al in cytoplasm and compartmentalizes Al into vacuoles, thereby reduce the toxicity of Al to plants..

The root anatomical phenotype root cortical aerenchyma (RCA) decreases the metabolic cost of soil exploration and improves plant growth under drought and low soil fertility. RCA may also change the microenvironment of rhizosphere microorganisms by increasing oxygen availability or by reducing carbon rhizodeposition. We tested the hypothesis that plants with contrasting expression of RCA have different rhizosphere prokaryotic communities. Maize inbreds were grown in two field sites, Limpopo Province, South Africa and Pennsylvania, USA, and their rhizosphere soil sampled at flowering. High- and low-nitrogen fertilization was imposed as separate treatments in the experiment in South Africa. The rhizosphere microbial composition of plants with contrasting RCA was characterized by metabarcoding of the 16S rRNA genes. Geographic location was the most important factor related to the composition of rhizosphere microbial communities. In the site in South Africa, RCA explained greater percent of variance (9%) in the composition of microbial communities than genotype (7%). Although other root anatomical and architectural phenotypes were studied as possible cofactors affecting the microbial composition, RCA was among the best significant explanatory variables for the South African site although it was neutral in the Pennsylvania site. High-RCA rhizospheres significantly enriched OTUs of the families Burkholderiaceae (in South Africa) and Bacillaceae (in USA), compared to low-RCA plants, and OTUs of the families Beijerinckiaceae and Sphingomonadaceae were enriched at the two nitrogen levels in high RCA plants in South Africa. Our results are consistent with the hypothesis that RCA is an important factor for rhizosphere microbial communities, especially under suboptimal nitrogen conditions.