External validation of the SYNTAX score II 2020 in patients with chronic renal insufficiency.

BACKGROUND: The SYNTAX score Ⅱ 2020 (SSⅡ-2020) was created as a customized decision-making tool for individuals diagnosed with complex coronary artery disease (CAD). Nevertheless, there has been a scarcity of research investigating the long-term predictive significance of SSⅡ-2020 for patients with both CAD and chronic renal insufficiency (CRI) who undergo percutaneous coronary intervention (PCI). AIMS: We sought to showcase the prognostic capacity of SSII-2020 in evaluating long-term all-cause mortality (ACM) within this high-risk patient cohort. METHODS: A retrospective cohort comprising 1156 individuals diagnosed with CRI and exhibiting left main CAD, three-vessel CAD or both was included in this investigation. We categorized participants into three groups based on the optimal SSII-2020 threshold for predicting long-term ACM, determined using the X-tile software. RESULTS: At the median follow-up duration of 6.3 years, the ACM rates were determined to be 10% in the low, 17% in the moderate, and 28% in the high SSII-2020 groups (p < 0.001). Employing multivariate Cox regression analysis, it was observed that the high SSII-2020 group exhibited a 3.289-fold increased risk of ACM (95% confidence interval [CI]: 2.229-4.856, p < 0.001) compared with the low SSII-2020 group, whereas the high SSII-2020 group displayed a 1.757-fold (95% CI: 1.190-2.597, p = 0.005) in comparison to the median SSII-2020 groups. Compared with SSII, the SSII-2020 had an incremental value for predicting 7-year ACM (C-index: 0.662 vs. 0.534, p = 0.007; IDI: 0.016, p < 0.001). CONCLUSIONS: SSII-2020 enhances long-term ACM prediction, facilitates improved risk stratification, and improves clinical utility for PCI patients with complex CAD and CRI.

Fertilization Weakens the Ecological Succession of Dissolved Organic Matter in Paddy Rice Rhizosphere Soil at the Molecular Level.

Dissolved organic matter (DOM) is involved in numerous biogeochemical processes, and understanding the ecological succession of DOM is crucial for predicting its response to farming (e.g., fertilization) practices. Although plentiful studies have examined how fertilization practice affects the content of soil DOM, it remains unknown how long-term fertilization drives the succession of soil DOM over temporal scales. Here, we investigated the succession of DOM in paddy rice rhizosphere soils subjected to different long-term fertilization treatments (CK: no fertilization; NPK: inorganic fertilization; OM: organic fertilization) along with plant growth. Our results demonstrated that long-term fertilization significantly promoted the molecular chemodiversity of DOM, but it weakened the correlation between DOM composition and plant development. Time-decay analysis indicated that the DOM composition had a shorter halving time under CK treatment (94.7 days), compared to NPK (337.4 days) and OM (223.8 days) treatments, reflecting a lower molecular turnover rate of DOM under fertilization. Moreover, plant development significantly affected the assembly process of DOM only under CK, not under NPK and OM treatments. Taken together, our results demonstrated that long-term fertilization, especially inorganic fertilization, greatly weakens the ecological succession of DOM in the plant rhizosphere, which has a profound implication for understanding the complex plant-DOM interactions.

Global diversity and biogeography of potential phytopathogenic fungi in a changing world.

Phytopathogenic fungi threaten global food security but the ecological drivers of their global diversity and biogeography remain unknown. Here, we construct and analyse a global atlas of potential phytopathogenic fungi from 20,312 samples across all continents and major oceanic island regions, eleven land cover types, and twelve habitat types. We show a peak in the diversity of phytopathogenic fungi in mid-latitude regions, in contrast to the latitudinal diversity gradients observed in aboveground organisms. Our study identifies climate as an important driver of the global distribution of phytopathogenic fungi, and our models suggest that their diversity and invasion potential will increase globally by 2100. Importantly, phytopathogen diversity will increase largely in forest (37.27-79.12%) and cropland (34.93-82.51%) ecosystems, and this becomes more pronounced under fossil-fuelled industry dependent future scenarios. Thus, we recommend improved biomonitoring in forests and croplands, and optimised sustainable development approaches to reduce potential threats from phytopathogenic fungi.

Fossil-fuel-dependent scenarios could lead to a significant decline of global plant-beneficial bacteria abundance in soils by 2100.

Exploiting the potential benefits of plant-associated microbes represents a sustainable approach to enhancing crop productivity. Plant-beneficial bacteria (PBB) provide multiple benefits to plants. However, the biogeography and community structure remain largely unknown. Here we constructed a PBB database to couple microbial taxonomy with their plant-beneficial traits and analysed the global atlas of potential PBB from 4,245 soil samples. We show that the diversity of PBB peaks in low-latitude regions, following a strong latitudinal diversity gradient. The distribution of potential PBB was primarily governed by environmental filtering, which was mainly determined by local climate. Our projections showed that fossil-fuel-dependent future scenarios would lead to a significant decline of potential PBB by 2100, especially biocontrol agents (-1.03%) and stress resistance bacteria (-0.61%), which may potentially threaten global food production and (agro)ecosystem services.

Changes in soil stoichiometry, soil organic carbon mineralization and bacterial community assembly processes across soil profiles.

Soil organic carbon (SOC) mineralization is essential to biogeochemical recycling in terrestrial ecosystem. However, the microbial mechanisms underlying the nutrient-induced SOC mineralization remain uncertain. Here, we investigated how SOC mineralization was linked to microbial assembly processes as well as soil nutrient availability and stoichiometric ratio in a paddy rice ecosystem at four soil profile levels. Our results showed a sharp decrease in SOC mineralization from topsoil (112.61-146.34 mg CO2 kg-1 day-1) to subsoil (33.51-61.41 mg CO2 kg-1 day-1). High-throughput sequencing showed that both abundance and diversity of specialist microorganisms (Chao1: 1244.30-1341.35) significantly increased along the soil profile, while the generalist microorganisms (Chao1: 427.67-616.15; Shannon: 7.46-7.97) showed the opposite trend. Correspondingly, the proportion of deterministic processes that regulate specialist (9.64-21.59 %) and generalist microorganisms (21.17-53.53 %) increased and decreased from topsoil to subsoil, respectively. Linear regression modeling and partial least squares path modeling indicated that SOC mineralization was primarily controlled by the assembly processes of specialist microorganisms, which was significantly mediated by available soil C:N:P stoichiometry. This study highlighted the importance of soil stoichiometry-mediated bacterial community assembly processes in regulating SOC mineralization. Our results have an important implication for the integration of bacterial community assembly processes into the prediction of SOC dynamics.

Potential effect of key soil bacterial taxa on the increase of rice yield under milk vetch rotation.

Legume crop rotation is often adopted in rice cultivation to improve soil productivity. However, little is known about the role of microbes under legume rotation in affecting soil productivity. To elucidate this, a long-term paddy cropping experiment was set up to study the relationship between crop yield, soil chemical properties, and key microbial taxa under a double-rice and milk vetch rotation. Milk vetch rotation significantly improved soil chemical properties compared to no fertilization treatment, and soil phosphorus was a major factor correlated with crop yield. Long-term legume rotation increased soil bacterial alpha diversity and changed soil bacterial community. After milk vetch rotation, the relative abundances of Bacteroidota, Desulfobacterota, Firmicutes, and Proteobacteria increased while those of Acidobacteriota, Chloroflexi, and Planctomycetota decreased. Moreover, milk vetch rotation increased the relative abundance of phosphorus-related gene K01083 (bpp), which was significantly correlated with soil phosphorus content and crop yield. Network analysis showed that taxa of Vicinamibacterales were positively correlated with total phosphorus and available phosphorus, which was a potential taxon contributing to the availability of soil phosphorus stock. Our results indicated that milk vetch rotation could enrich key taxa with latent phosphate-solubilizing ability, increase the content of soil available phosphorus, and finally enhance crop yield. This could provide scientific guidance for better crop production.

Temperature and moisture mediated changes in chemical and microbial properties of biochars in an Anthrosol.

Sequestration of soil carbon is considered as a promising strategy for mitigating climate change. As a source of recalcitrant carbon, biochar has been widely used in agricultural soil as a mean of stabilizing soil organic carbon (SOC). However, limited reports focused on the changes of biochar itself in soil when compared with the bulk SOC after biochar addition. To explore how environmental conditions influence the stability of biochar, isolated straw-derived biochar particles (0.25-2 mm) were embedded in an Anthrosol for 12 months under varied environmental conditions of incubation temperature (15 °C, 25 °C and 35 °C) and moisture (60 % and 150 % of saturated water content). Within the early 1 month of incubation, pH and inorganic nitrogen contents of biochar changed significantly as a function of moisture and temperature (p < 0.01), whereas water extractable organic carbon (WEOC) content was only influenced by moisture content (p < 0.01). The highest temperature (35 °C) and saturated water content (150 %) induced the largest aging response reflected by increases in oxygen-containing surface functional groups of biochar, including C-O-C (51.35 % - 149 %) and N-C-O (65.55 % - 119 %). Pearson correlation and RDA analysis indicated that the chemical properties of biochar contribute more to the carbon-source utilization properties of biochar colonized microbial community within 1 month of incubation, while the bulk soil chemical properties (pH, DOC, MBC and NO3-) had a higher contribution until the end of incubation. Moisture rather than temperature was the dominant factor in regulating the functional diversity of biochar colonized microbial community.

Reduced chemodiversity suppresses rhizosphere microbiome functioning in the mono-cropped agroecosystems.

BACKGROUND: Rhizodeposits regulate rhizosphere interactions, processes, nutrient and energy flow, and plant-microbe communication and thus play a vital role in maintaining soil and plant health. However, it remains unclear whether and how alteration in belowground carbon allocation and chemodiversity of rhizodeposits influences microbiome functioning in the rhizosphere ecosystems. To address this research gap, we investigated the relationship of rhizosphere carbon allocation and chemodiversity with microbiome biodiversity and functioning during peanut (Arachis hypogaea) continuous mono-cropping. After continuously labeling plants with 13CO2, we studied the chemodiversity and composition of rhizodeposits, along with the composition and diversity of active rhizosphere microbiome using metabolomic, amplicon, and shotgun metagenomic sequencing approaches based on DNA stable-isotope probing (DNA-SIP). RESULTS: Our results indicated that enrichment and depletion of rhizodeposits and active microbial taxa varied across plant growth stages and cropping durations. Specifically, a gradual decrease in the rhizosphere carbon allocation, chemodiversity, biodiversity and abundance of plant-beneficial taxa (such as Gemmatimonas, Streptomyces, Ramlibacter, and Lysobacter), and functional gene pathways (such as quorum sensing and biosynthesis of antibiotics) was observed with years of mono-cropping. We detected significant and strong correlations between rhizodeposits and rhizosphere microbiome biodiversity and functioning, though these were regulated by different ecological processes. For instance, rhizodeposits and active bacterial communities were mainly governed by deterministic and stochastic processes, respectively. Overall, the reduction in carbon deposition and chemodiversity during peanut continuous mono-cropping tended to suppress microbial biodiversity and its functions in the rhizosphere ecosystem. CONCLUSIONS: Our results, for the first time, provide the evidence underlying the mechanism of rhizosphere microbiome malfunctioning in mono-cropped systems. Our study opens new avenues to deeply disentangle the complex plant-microbe interactions from the perspective of rhizodeposits chemodiversity and composition and will serve to guide future microbiome research for improving the functioning and services of soil ecosystems. Video abstract.

Using Potential Molecular Transformation To Understand the Molecular Trade-Offs in Soil Dissolved Organic Matter.

Understanding the chemical composition and molecular transformation in soil dissolved organic matter (DOM) is important to the global carbon cycle. To address this issue, ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was applied to investigate DOM molecules in 36 paddy soils collected from subtropical China. All the detected 7576 unique molecules were divided into seven compound groups, and nine trade-off relationships between different compound groups were revealed based on principal component analysis and Pearson's correlation. An optimized method was developed to evaluate all potential molecular transformations in DOM samples. The concept of thermodynamics was introduced to evaluate the identified molecular transformations and classify them as thermodynamically favorable (TFP) and thermodynamically limited (TLP) processes. Here, we first tried to understand the molecular trade-offs by using the potential molecular transformations. All the nine trade-offs could be explained by molecular transformations. Six trade-offs had bases of biochemical reactions, and the trade-off-related direct transformations could explain the content variations of carbohydrate-like, condensed aromatic-like, tannin-like, and lignin-like compounds in TLP. More reasonable explanations existed in the TLP rather than TFP, which demonstrated the critical role of external energy in the molecular transformation of soil DOM.

Phosphorus availability increases pathobiome abundance and invasion of rhizosphere microbial networks by Ralstonia.

Soil disease-suppressiveness depends on complex interactions among pathogens, native microbiota, and physicochemical properties, while these interactions remain understudied. Comparing field and microcosm experiments, we investigated the significance of these interactions in disease emergence or suppression using structural equation modelling (SEM) and receiver operating characteristic curve (ROC) analyses. We observed significant differences in the relative abundance of pathogenic and beneficial microbes, alpha and beta diversity indices between disease-conducive and -suppressive rhizosphere soils. The pathogenic (Ralstonia) and beneficial (Bacillus) taxa dominated disease-conducive and -suppressive rhizosphere soils, respectively. Moreover, the co-occurrences of Ralstonia with native microorganisms were positive and negative in the disease-conducive and -suppressive soils, respectively. These results suggest the supportive (Rudaea) and suppressive (Enterobacter, Bacillus) role of indigenous microbes in the invasion of soil and plant systems by Ralstonia. The SEM and ROC analysis predicted that Ralstonia invaded rhizospheric microbial networks and caused peanut wilt under high than low soil phosphorus conditions. Our results suggest the importance of soil phosphorus availability in altering the microbial interactions, thus leading to soil invasion by Ralstonia. Thus, we conclude by saying that feeding soil with high amounts of available phosphorus could deplete plant-beneficial microbes and increase the pathobiome abundance that may compromise plant health.

Assessing the ecological risk of pesticides should not ignore the impact of their transformation byproducts - The case of chlorantraniliprole.

Risk assessments for pesticides typically focus on the compound itself ignoring the impact of its transformation byproducts. Challenges in isolating such byproducts (i.e. after application of pesticide in soil) often lead to underestimation of the real risk from such substances. The toxicological properties of these byproducts may differ from those of the parent pesticides; hence, special attention is required for these new emerging contaminants. In this study, two transformation byproducts of chlorantraniliprole were isolated from soil and identified, using nuclear magnetic resonance and high resolution mass spectrometry, as products of dechlorination (Z1) and bromination (Z2). Kinetic experiments revealed both byproducts degrade faster than chlorantraniliprole in soil (half-lives 38 & 43 d vs. 58 d). The ecological risk evaluation of chlorantraniliprole and its byproducts on soil bacterial community showed that they were all potentially harmful but they imposed different impacts on both alpha and beta diversities and co-occurrence networks of the bacterial community. Z2 had the biggest potential impact on soil bacteria and accounted as a high potential risk. By comparing their impacts on soil bacterial community, we confirm that ecological risk assessment necessitates the understanding of the environmental impacts of a substance as well as of its transformation byproducts.

Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils.

BACKGROUND: Microbial-driven decomposition of plant residues is integral to carbon sequestration in terrestrial ecosystems. Actinobacteria, one of the most widely distributed bacterial phyla in soils, are known for their ability to degrade plant residues in vitro. However, their in situ importance and specific activity across contrasting ecological environments are not known. Here, we conducted three field experiments with buried straw in combination with microcosm experiments with 13C-straw in paddy soils under different soil fertility levels to reveal the ecophysiological roles of Actinobacteria in plant residue decomposition. RESULTS: While accounting for only 4.6% of the total bacterial abundance, the Actinobacteria encoded 16% of total abundance of carbohydrate-active enzymes (CAZymes). The taxonomic and functional compositions of the Actinobacteria were, surprisingly, relatively stable during straw decomposition. Slopes of linear regression models between straw chemical composition and Actinobacterial traits were flatter than those for other taxonomic groups at both local and regional scales due to holding genes encoding for full set of CAZymes, nitrogenases, and antibiotic synthetases. Ecological co-occurrence network and 13C-based metagenomic analyses both indicated that their importance for straw degradation increased in less fertile soils, as both links between Actinobacteria and other community members and relative abundances of their functional genes increased with decreasing soil fertility. CONCLUSIONS: This study provided DNA-based evidence that non-dominant Actinobacteria plays a key ecophysiological role in plant residue decomposition as their members possess high proportions of CAZymes and as a group maintain a relatively stable presence during plant residue decomposition both in terms of taxonomic composition and functional roles. Their importance for decomposition was more pronounced in less fertile soils where their possession functional genes and interspecies interactions stood out more. Our work provides new ecophysiological angles for the understanding of the importance of Actinobacteria in global carbon cycling. Video abstract.

Evaluation of Microbe-Driven Soil Organic Matter Quantity and Quality by Thermodynamic Theory.

Microbial communities, coupled with substrate quality and availability, regulate the stock (formation versus mineralization) of soil organic matter (SOM) in terrestrial ecosystems. However, our understanding of how soil microbes interact with contrasting substrates influencing SOM quantity and quality is still very superficial. Here, we used thermodynamic theory principles and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) to evaluate the linkages between dissolved organic matter (DOM [organic substrates in soil that are readily available]), thermodynamic quality, and microbial communities. We investigated soils from subtropical paddy ecosystems across a 1,000-km gradient and comprising contrasting levels of SOM content and nutrient availability. Our region-scale study suggested that soils with a larger abundance of readily accessible resources (i.e., lower Gibbs free energy) supported higher levels of microbial diversity and higher SOM content. We further advocated a novel phylotype-level microbial classification based on their associations with OM quantities and qualities and identified two contrasting clusters of bacterial taxa: phylotypes that are highly positively correlated with thermodynamically favorable DOM and larger SOM content versus those which are associated with less-favorable DOM and lower SOM content. Both groups are expected to play critical roles in regulating SOM contents in the soil. By identifying the associations between microbial phylotypes of different life strategies and OM qualities and quantities, our study indicates that thermodynamic theory can act as a proxy for the relationship between OM and soil microbial communities and should be considered in models of soil organic matter preservation.IMPORTANCE Microbial communities are known to be important drivers of organic matter (OM) accumulation in terrestrial ecosystems. However, despite the importance of these soil microbes and processes, the mechanisms behind these microbial-SOM associations remain poorly understood. Here, we used the principles of thermodynamic theory and novel Fourier transform ion cyclotron resonance mass spectrometry techniques to investigate the links between microbial communities and dissolved OM (DOM) thermodynamic quality in soils across a 1,000-km gradient and comprising contrasting nutrient and C contents. Our region-scale study provided evidence that soils with a larger amount of readily accessible resources (i.e., lower Gibbs free energy) supported higher levels of microbial diversity and larger SOM content. Moreover, we created a novel phylotype-level microbial classification based on the associations between microbial taxa and DOM quantities and qualities. We found two contrasting clusters of bacterial taxa based on their level of association with thermodynamically favorable DOM and SOM content. Our study advances our knowledge on the important links between microbial communities and SOM. Moreover, by identifying the associations between microbial phylotypes of different life strategies and OM qualities and quantities, our study indicates that thermodynamic theory can act as a proxy for the relationship between OM and soil microbial communities. Together, our findings support that the association between microbial species taxa and substrate thermodynamic quality constituted an important complement explanation for soil organic matter preservation.

Insights into enhanced biodegradation of sulfadimethoxine by catalyst: Transcriptomic responses and free radical interactions.

The occurrence of sulfonamides in the environment is a severe global threat to public health due to the increasing prevalence of antibiotic selection pressure that may lead to the development of antibiotic resistance. We report an enhanced biodegradation of sulfadimethoxine (SDM) by Phanerochaete chrysosporium (Pc) with lignocellulosic biomass (Lb) using Fe3O4-ZSM-5 as a catalyst (Pc/Fe3O4-ZSM-5/Lb). SDM was completely degraded within 4 days at pH 7.0 in the Pc/Fe3O4-ZSM-5/Lb system. Transcriptomic, metabolites and free radical analyses were performed to explore the detailed molecular mechanisms of SDM degradation. A total of 246 genes of Pc in the Pc/Fe3O4-ZSM-5/Lb system exhibited significant upregulation compared to that in Pc alone. Upregulated genes encoding cellulases, cytochrome P450, cellobiose quinone oxidoreductase, and cellobiose dehydrogenase were involved in SDM degradation in the Pc/Fe3O4-ZSM-5/Lb system. In addition, genes encoding glutathione S-transferase and cytochrome P450 genes related to oxidative stress and detoxification were all significantly upregulated (P < 0.01). Electron paramagnetic resonance revealed the generation of OH suggesting a free radical pathway could be catalyzed by Fe3O4-ZSM-5 and the enzymes. These findings of catalyst-assisted SDM biodegradation will be valuable for remediation of antibiotics from contaminated wastewater.

Molecular level changes during suppression of Rhizoctonia solani growth by humic substances and relationships with chemical structure.

Elucidation of the inhibitory effects of humic substances (HSs) on phytopathogenic fungi and the underlying molecular mechanisms are highly important for improved biocontrol. In this study, we investigated the growth suppression, morphological characteristics, transcriptomic sequence, and radical signals of Rhizoctonia solani following HS addition (50 mg/L). Through mycelial cultured experiment, mycelia growth of R. solani had been suppressed with HS addition, and the inhibition rate was 24.88 ± 0.11% compared to the control. Field emission-scanning electron microscopy showed increased and superimposed branching mycelial growth, with a shriveled appearance. RNA samples of R. solani cultured with or without HSs were both extracted to examine the sequence on molecular level by Illumina HiSeq sequencing platform. RNA sequencing analysis revealed 175 differentially expressed genes (DEGs; 111 upregulated and 64 downregulated) between the HSs treatment and control. The upregulated unigenes were annotated and significantly enriched to three molecular processes: vitamin B6 metabolism, ABC transporters, and glutathione metabolism, while the downregulated unigenes were annotated to carbohydrate metabolism, but not significantly enriched. Real time-quantitative polymerase chain reaction analysis showed that the unigenes related to hexokinase, glucose-6-phosphate isomerase, glutathione synthase, and glutathione reductase were significantly decreased (by 60.03%, 70.70%, 60.33%, and 57.59%, respectively), while those related to glutathione S-transferase were significantly increased (2.66-fold). The electron paramagnetic resonance spectra showed that HSs induced increased the intensity of radical signals of R. solani in a cultured system increased by 59.56% compared to CK (without HSs addition). Network analysis based on DEGs expression and the chemical structure of HSs revealed that the carbonyl moiety in HSs formed the most links with nodes of the DEGs (sum of the links of positive and negative effects = 70), implicating this structure as the active fraction responsible for the inhibitory effect. This study provides molecular and chemical evidence of the biofungicidal activity of HSs with the potential for practical application.

Biodegradation mechanisms of sulfonamides by Phanerochaete chrysosporium - Luffa fiber system revealed at the transcriptome level.

The overuse of antibiotics and subsequent enrichment of antibiotic resistant microbes in the natural and built environments is a severe threat to global public health. In this study, a Phanerochaete chrysosporium fungal-luffa fiber system was found to efficiently biodegrade two sulfonamides, sulfadimethoxine (SDM) and sulfadizine (SDZ), in cow urine wastewater. Biodegradation pathways were proposed on the basis of key metabolites identified using high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (HPLC-QqTOF-MS). Transcriptomic, metabolomic, and free radical analyses were performed to explore the functional groups and detailed molecular mechanisms of SDM and SDZ degradation. A total of 27 UniGene clusters showed significant differences between luffa fiber and luffa fiber-free systems, which were significantly correlated to cellulose catabolism, carbohydrate metabolism, and oxidoreductase activity. Carbohydrate-active enzymes and oxidoreductases appear to play particularly important roles in SDM and SDZ degradation. Electron paramagnetic resonance (EPR) spectroscopy revealed the generation and evolution of OH and R during the biodegradation of SDM and SDZ, suggesting that beyond enzymatic degradation, SDM and SDZ were also transformed through a free radical pathway. Luffa fiber also acts as a co-substrate to improve the activity of enzymes for the degradation of SDM and SDZ. This research provides a potential strategy for removing SDM and SDZ from agricultural and industrial wastewater using fungal-luffa fiber systems.

Does anaerobic condition play a more positive role in dissipation of antibiotic resistance genes in soil?

The persistence of antibiotic resistance genes (ARGs) under the aerobic vs. anaerobic conditions is unknown, especially under different fertilization. Towards this goal, a microcosm experiment was carried out with chemical fertilized and manured soil under aerobic and anaerobic conditions. High throughput qPCR was used to analyze ARGs with 144 primer sets and sequencing for microorganisms. Completely different dynamics of ARGs were observed in soil under aerobic and anaerobic conditions, regardless of the fertilization type. ARGs had different half-lives, even though they confer resistance to the same type of antibiotics. Aminoglycoside, chloramphenicol, macrolide - lincosamide - streptogramin B (MLSB) and tetracycline resistance genes were significantly accumulated in the aerobic soils. Anaerobic soil possessed a higher harboring capacity for exogenous microorganisms and ARGs than aerobic soil. The interaction between ARGs and mobile genetic elements (MGEs) in manured soil under aerobic condition was more pronounced than the anaerobic condition. These findings unveil that anaerobic soil could play a more positive role in reducing potential risk of ARGs in the farmland environment.

Soil microbiome-induced changes in the priming effects of 13C-labelled substrates from rice residues.

Knowledge gap exists to understand the soil CO2 emission and microbial group response to substrates of whole plant residues and derived biochar. We used 13C-labelled substrates (rice straw, roots and biochar) to track influences of their decomposition on soil priming effect (PE) and phospholipid fatty acid (PLFA) composition during one-year incubation. Organic substrates at 1% (w/w) level increased soil pH, available nitrogen (AN) and available phosphorus (AP), especially during the first 45 days of incubation. After incubation, 44% of the added straw was mineralized to 13CO2, followed by roots (~35%) and biochar (~5%). Straw and roots amendment caused positive PE during 4-360 day of the incubation, where a lowest value of 41.9 mg C kg-1 was observed. Biochar amendment caused negative PE during 56-150 day of the incubation, where a largest value of -99.0 mg C kg-1 was observed. Analysis of 13C-labelled PLFA enabled the differentiation of microbial groups during substrates utilization. Gram positive bacteria (G+) and general bacteria groups were dominated in co-metabolizing both the native soil organic carbon (SOC) and substrates after straw and roots amendment. Gram negative bacteria (G-), especially identified by PLFA biomarkers cy17:0 and cy19:0, preferentially utilizes the 13C-labelled biochar but not promoting soil priming effect. Soil pH, SOC, AN and AP all explained changes of total and 13C-labelled PLFA contents (>75%, p < .05). Evidences showed that biochar is best in sequestering soil C pool, followed by straw and roots, and soil microbial groups in utilization of organic substances mediated SOC mineralization.

Postintroduction evolution contributes to the successful invasion of Chromolaena odorata.

The evolution of increased competitive ability (EICA) hypothesis states that, when introduced in a novel habitat, invasive species may reallocate resources from costly quantitative defense mechanisms against enemies to dispersal and reproduction; meanwhile, the refinement of EICA suggests that concentrations of toxins used for qualitative defense against generalist herbivores may increase. Previous studies considered that only few genotypes were introduced to the new range, whereas most studies to test the EICA (or the refinement of EICA) hypotheses did not consider founder effects.In this study, genetic and phenotypic data of Chromolaena odorata populations sampled across native and introduced ranges were combined to investigate the role of postintroduction evolution in the successful invasion of C. odorata.Compared with native populations, the introduced populations exhibited lower levels of genetic diversity. Moreover, different founder effects events were interpreted as the main cause of the genetic structure observed in introduced ranges. Three Florida, two Trinidad, and two Puerto Rico populations may have been the sources of the invasive C. odorata in Asia.When in free of competition conditions, C. odorata plants from introduced ranges perform better than those from native ranges at high nutrient supply but not at low nutrient level. The differences in performance due to competition were significantly greater for C. odorata plants from the native range than those from the introduced range at both nutrient levels. Moreover, the differences in performance by competition were significantly greater for putative source populations than for invasive populations.Quantities of three types of secondary compounds in leaves of invasive C. odorata populations were significantly higher than those in putative source populations. These results provide more accurate evidence that the competitive ability of the introduced C. odorata is increased with postintroduction evolution.