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Nonsense‐mediated decay (NMD) and autophagy play pivotal roles in restricting virus infection in plants. However, the interconnection between these two pathways in viral infections has not been explored. Here, it is shown that overexpression of NbSMG7 and NbUPF3 attenuates cucumber green mottle mosaic virus (CGMMV) infection by recognizing the viral internal termination codon and vice versa. NbSMG7 is subjected to autophagic degradation, which is executed by its interaction with one of the autophagy‐related proteins, NbATG8i. Mutation of the ATG8 interacting motif (AIM) in NbSMG7 (SMG7mAIM1) abolishes the interaction and comprises its autophagic degradation. Silencing of NbSMG7 and NbATG8i, or NbUPF3 and NbATG8i, compared to silencing each gene individually, leads to more virus accumulations, but overexpression of NbSMG7 and NbATG8i fails to achieve more potent virus inhibition. When CGMMV is co‐inoculated with NbSMG7mAIM1 or with NbUPF3, compared to co‐inoculating with NbSMG7 in NbATG8i transgene plants, the inoculated plants exhibit milder viral phenotypes. These findings reveal that NMD‐mediated virus inhibition is impaired by the autophagic degradation of SMG7 in a negative feedback loop, and a novel regulatory interplay between NMD and autophagy is uncovered, providing insights that are valuable in optimizing strategies to harness NMD and autophagy for combating viral infections. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen (N) fixation (SNF), replenishing bioavailable N for terrestrial ecosystems, exerts decisive roles in N cycling and gross primary production. Nevertheless, it remains unclear what determines the variability of SNF rate, which retards the accurate prediction for global N fixation in earth system models. This study synthesized 1230 isotopic observations to elucidate the governing factors underlying the variability of SNF rate. The SNF rates varied significantly from 3.69 to 12.54 g N m−2 year−1 across host plant taxa. The traits of host plant (e.g. biomass characteristics and taxa) far outweighed soil properties and climatic factors in explaining the variations of SNF rate, accounting for 79.0% of total relative importance. Furthermore, annual SNF yield contributed to more than half of N uptake for host plants, which was consistent across different ecosystem types. This study highlights that the biotic factors, especially host plant traits (e.g. biomass characteristics and taxa), play overriding roles in determining SNF rate compared with soil properties. The suite of parameters for SNF lends support to improve N fixation module in earth system models that can provide more confidence in predicting bioavailable N changes in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a potent greenhouse gas, and its mitigation is a pressing task in the coming decade. However, it remains unclear which specific process between concurrent nitrification and denitrification dominates worldwide N2O emission. We snagged an opportunity to ascertain whence the N2O came and which were the controlling factors on the basis of 1315 soil N2O observations from 74 peer‐reviewed articles. The average N2O emission derived from nitrification (N2On) was higher than that from denitrification (N2Od) worldwide. The ratios of nitrification‐derived N2O to denitrification‐derived N2O, hereof N2On:N2Od, exhibited large variations across terrestrial ecosystems. Although soil carbon and nitrogen content, pH, moisture, and clay content accounted for a part of the geographical variations in the N2On:N2Od ratio, ammonia‐oxidizing microorganisms (AOM):denitrifier ratio was the pivotal driver for the N2On:N2Od ratios, since the AOM:denitrfier ratio accounted for 53.7% of geographical variations in N2On:N2Od ratios. Compared with natural ecosystems, soil pH exerted a more remarkable role to dictate the N2On:N2Od ratio in croplands. This study emphasizes the vital role of functional soil microorganisms in geographical variations of N2On:N2Od ratio and lays the foundation for the incorporation of soil AOM:denitrfier ratio into models to better predict N2On:N2Od ratio. Identifying soil N2O derivation will provide a global potential benchmark for N2O mitigation by manipulating the nitrification or denitrification. [ABSTRACT FROM AUTHOR]

Aim: The accumulation of microbial necromass carbon has gained increasing attention due to its slow decomposition. However, it remains unclear what induces the accumulation of microbial necromass carbon via reiterated community turnover on large spatial scales. This study explores the characteristics of soil necromass carbon accumulation in terrestrial ecosystems. Location: Global. Time Period: Contemporary (1999–2022). Major Taxa Studied: Soil microorganisms. Methods: A dataset was compiled using 993 observations from 82 peer‐reviewed papers on the effects of coefficients of microbial necromass accumulation (hereafter NAC) in equilibrium. Linear mixed‐effect models and structural equation models were used to ascertain the controlling factors of the NAC. Results: The average NAC was higher in croplands (28.2) and forests (26.8) than in grasslands (21.1). Edaphic factors seemingly affected the NAC, which was lower in soils with high pH and clay content on a global scale. Biotic factors, particularly those related to living microorganism abundance and microbial biomass nitrogen content, were the pivotal drivers of NAC and accounted for approximately 43.6% of its geographic variability. More organic carbon was likely to be preserved in soil with a higher NAC, regardless of ecosystem type. Conclusions: Novel findings regarding the overriding controls for the living microorganism abundance and microbial biomass nitrogen that drive the NAC highlight an urgent need for viable strategies to manipulate microbial attributes for enhancing carbon sequestration. [ABSTRACT FROM AUTHOR]

Climate change leads to increasing temperature and more extreme hot and drought events. Ecosystem capability to cope with climate warming depends on vegetation's adjusting pace with temperature change. How environmental stresses impair such a vegetation pace has not been carefully investigated. Here we show that dryness substantially dampens vegetation pace in warm regions to adjust the optimal temperature of gross primary production (GPP) (ToptGPP) in response to change in temperature over space and time. ToptGPP spatially converges to an increase of 1.01°C (95% CI: 0.97, 1.05) per 1°C increase in the yearly maximum temperature (Tmax) across humid or cold sites worldwide (37oS–79oN) but only 0.59°C (95% CI: 0.46, 0.74) per 1°C increase in Tmax across dry and warm sites. ToptGPP temporally changes by 0.81°C (95% CI: 0.75, 0.87) per 1°C interannual variation in Tmax at humid or cold sites and 0.42°C (95% CI: 0.17, 0.66) at dry and warm sites. Regardless of the water limitation, the maximum GPP (GPPmax) similarly increases by 0.23 g C m−2 day−1 per 1°C increase in ToptGPP in either humid or dry areas. Our results indicate that the future climate warming likely stimulates vegetation productivity more substantially in humid than water‐limited regions. [ABSTRACT FROM AUTHOR]

Soil anammox is an environmentally friendly way to eliminate reactive nitrogen (N) without generating nitrous oxide. Nevertheless, the current earth system models have not incorporated the anammox due to the lack of parameters in anammox rates on a global scale, limiting the accurate projection for N cycling. A global synthesis with 1212 observations from 89 peer‐reviewed papers showed that the average anammox rate was 1.60 ± 0.17 nmol N g−1 h−1 in terrestrial ecosystems, with significant variations across different ecosystems. Wetlands exhibited the highest rate (2.17 ± 0.31 nmol N g−1 h−1), followed by croplands at 1.02 ± 0.09 nmol N g−1 h−1. The lowest anammox rates were observed in forests and grasslands. The anammox rates were positively correlated with the mean annual temperature, mean annual precipitation, soil moisture, organic carbon (C), total N, as well as nitrite and ammonium concentrations, but negatively with the soil C:N ratio. Structural equation models revealed that the geographical variations in anammox rates were primarily influenced by the N contents (such as nitrite and ammonium) and abundance of anammox bacteria, which collectively accounted for 42% of the observed variance. Furthermore, the abundance of anammox bacteria was well simulated by the mean annual precipitation, soil moisture, and ammonium concentrations, and 51% variance of the anammox bacteria was accounted for. The key controlling factors for soil anammox rates differed from ecosystem type, for example, organic C, total N, and ammonium contents in croplands, versus soil C:N ratio and nitrite concentrations in wetlands. The controlling factors in soil anammox rate identified by this study are useful to construct an accurate anammox module for N cycling in earth system models. [ABSTRACT FROM AUTHOR]

As awareness of the importance of anthropogenic climate change has increased, attention is being focused on "compound extremes," such as co‐occurring soil drought (low amounts of soil moisture, SM) and atmospheric aridity (high vapor‐pressure deficits, VPD), because of the disproportionate impacts of such extreme conditions on natural and societal systems. Few advances, however, have been made in isolating the net effect of anthropogenic forcing on the occurrence of such compound extremes. Nine Earth System models (ESMs) under natural‐only and fully‐forced simulations from Phase 6 of the Coupled Model Intercomparison Project (CMIP6) indicated that the presence of anthropogenic forcing in the historical period 1850–2013 weakened the coupling between SM and VPD and thus decreased the frequency of compound drought and aridity globally. The anthropogenically induced decrease in the strength of land–atmospheric feedbacks, which offset the drying trend effects of global warming by countering the expected natural correlation between SM and VPD, appears to have been responsible for the relative rarity of concurrent drought and aridity in the historical period. We also modeled independently the anthropogenic forcings of aerosols and greenhouse gases (GHGs) to further highlight that the widespread weakening of land–atmospheric feedbacks may have been associated primarily with the cooling effects induced by increases in anthropogenic emissions of aerosols, because the increase in intensity and frequency of compound drought and aridity that might have been expected from rising GHG concentrations was widely counter‐balanced until very recently by an aerosol‐driven cooling, particularly for the middle and high latitudes of the Northern Hemisphere. This finding indicates that the trade‐off between these two main anthropogenic forcings may determine future patterns of concurrent drought and aridity in a changing climate. If global emissions of anthropogenic aerosols decrease in the future, as expected, our results imply a renewed strengthening of land–atmospheric feedbacks, and thus an intensification of concurrent drought and aridity. Plain Language Summary: Compound drought (low soil moisture, SM) and atmospheric aridity (high vapor pressure deficit, VPD) are receiving increasing attention because of their disproportionate impacts on natural and societal systems. Few advances, however, have been made in isolating the net effect of anthropogenic forcing on the occurrence of such compound extremes. Using output data from nine Earth System Models under natural‐only and fully forced simulations from the Coupled Model Inter‐comparison Project Phase 6, we interestingly found that the presence of anthropogenic forcing actually weakened the negative coupling between low SM and high VPD and thus decreased the frequency of compound drought and aridity globally in the historical period 1850–2013. The anthropogenically induced decrease in the strength of land‐atmospheric feedbacks are primarily responsible for such decreased compound drought and aridity events. Using individual anthropogenic aerosol (AER) and greenhouse gas (GHG) forcings, we further highlighted that the widespread weakened land–atmospheric feedbacks may tightly associate with aerosol‐induced cooling, because a GHG‐driven increase in frequency and intensity of concurrent drought and aridity have been largely balanced by aerosol‐driven cooling throughout the historical period. If, as expected, global AER emissions decline in future, our results imply an intensification of concurrent drought and aridity. Key Points: Anthropogenic forcings decreased the frequency of compound soil drought and atmospheric aridity in the historical periodAnthropogenically weakened land‐atmospheric feedbacks largely responsible for the decreased concurrent low soil moisture and high vapor‐pressure deficit extremesWeakened land‐atmospheric feedbacks were associated primarily with the aerosol cooling effects [ABSTRACT FROM AUTHOR]

Ecological restoration is essential to reverse land degradation worldwide. Most studies have assessed the restoration of ecosystem functions individually, as opposed to a holistic view. Here we developed a network‐based ecosystem multifunctionality (EMF) framework to identify key functions in evaluating EMF restoration. Through synthesizing 293 restoration studies (2900 observations) following cropland abandonment, we found that individual soil functions played different roles in determining the restoration of belowground EMF. Soil carbon, total nitrogen, and phosphatase were key functions to predict the recovery of belowground EMF. On average, abandoned cropland recovered ~19% of EMF during 18 years. The restoration of EMF became larger with longer recovery time and higher humidity index, but lower with increasing soil depth and initial soil carbon. Overall, this study presents a network‐based EMF framework, effectively helping to evaluate the success of ecosystem restoration and identify the key functions. [ABSTRACT FROM AUTHOR]

Summary: Posttranslational modifications (PTMs) play important roles in virus–host interplay. We previously demonstrated that Barley stripe mosaic virus (BSMV) γb protein is phosphorylated by different host kinases to support or impede viral infection. However, whether and how other types of PTMs participate in BSMV infection remains to be explored.Here, we report that S‐adenosylmethionine decarboxylase 3 (SAMDC3) from Nicotiana benthamiana or wheat (Triticum aestivum) interacts with γb. BSMV infection induced SAMDC3 expression. Overexpression of SAMDC3 led to the destabilization of γb and reduction in viral infectivity, whereas knocking out NbSAMDC3 increased susceptibility to BSMV.NbSAMDC3 positively regulated the 26S proteasome‐mediated degradation of γb via its PEST domain. Further mechanistic studies revealed that γb can be ubiquitinated in planta and that NbSAMDC3 promotes the proteasomal degradation of γb by increasing γb ubiquitination. We also found evidence that ubiquitination occurs at nonlysine residues (Ser‐133 and Cys‐144) within γb.Together, our results provide a function for SAMDC3 in defence against BSMV infection through targeting of γb abundance, which contributes to our understanding of how a plant host deploys the ubiquitin–proteasome system to mount defences against viral infections. [ABSTRACT FROM AUTHOR]

The denitrification process profoundly affects soil nitrogen (N) availability and generates its byproduct, nitrous oxide, as a potent greenhouse gas. There are large uncertainties in predicting global denitrification because its controlling factors remain elusive. In this study, we compiled 4301 observations of denitrification rates across a variety of terrestrial ecosystems from 214 papers published in the literature. The averaged denitrification rate was 3516.3 ± 91.1 µg N kg−1 soil day−1. The highest denitrification rate was 4242.3 ± 152.3 µg N kg−1 soil day−1 under humid subtropical climates, and the lowest was 965.8 ± 150.4 µg N kg−1 under dry climates. The denitrification rate increased with temperature, precipitation, soil carbon and N contents, as well as microbial biomass carbon and N, but decreased with soil clay contents. The variables related to soil N contents (e.g., nitrate, ammonium, and total N) explained the variation of denitrification more than climatic and edaphic variables (e.g., mean annual temperature (MAT), soil moisture, soil pH, and clay content) according to structural equation models. Soil microbial biomass carbon, which was influenced by soil nitrate, ammonium, and total N, also strongly influenced denitrification at a global scale. Collectively, soil N contents, microbial biomass, pH, texture, moisture, and MAT accounted for 60% of the variation in global denitrification rates. The findings suggest that soil N contents and microbial biomass are strong predictors of denitrification at the global scale. [ABSTRACT FROM AUTHOR]

Aim: Biodiversity drives the delivery of multiple ecosystem functions related to carbon and nutrient cycling (ecosystem multifunctionality, EMF), and biodiversity and ecosystem functioning are strongly threatened by intensive grazing in grasslands. However, it remains unclear how biodiversity regulates EMF changes in response to intensive grazing. Location: Global. Time period: From 1992 to 2018. Major taxa studied: Grassland. Methods: Here, we conducted a global synthesis using 373 paired observations from 90 published studies to address the responses of plant diversity, EMF and their relationships to grazing disturbance depending on grazing intensity, livestock type, grazing duration, and climatic aridity. Results: Our results showed that EMF significantly decreased with increasing grazing intensity, but the negative EMF response was alleviated at high levels of plant diversity. The grazing‐induced changes in EMF increased linearly with the changes in plant diversity, with the slopes increasing by 78.9% from light to heavy grazing. In addition, the grazing‐induced decrease of EMF was stronger with longer grazing duration and more arid climates. Structural equation models suggested that grazing intensity reduced EMF largely via decreasing plant diversity, whereas upsizing livestock type promoted EMF by increasing plant diversity. Main conclusions: This study highlights the key role of biodiversity in mediating EMF in response to intensifying grazing disturbance. We call for conservation of biodiversity to maintain grassland multifunctionality and services. [ABSTRACT FROM AUTHOR]

Ecosystem trait is a standardized description of biological features of a community, and it bridges individual plants and ecosystem. Conventionally most ecosystem trait data are collected from field survey and the generated data is hard to meet the requirements as set in the concept of ecosystem trait. To a great extent, remotely piloted aircraft systems (RPAS) remote sensing, which is capable of retrieving ecosystem traits across multiple scales, can overcome constraints in field plot survey. In this study, we selected alpine grassland ecosystem on the Tibetan Plateau (TP), which is under‐studied due to scarcity of field monitoring data, as the research target. A new data framework was proposed by integrating field plot and RPAS remote sensing data to map spatial patterns of ecosystem traits for the alpine grasslands. Across four landscapes on the TP, ecosystem traits of vegetation coverage (CVC), species number (CSN), individual number (CIN), above ground biomass (AGB), organic carbon content (OC%) and total nitrogen content (TN%) were retrieved. We also calculated Shannon's Diversity Index and Shannon's Evenness Index for each plot. The results showed that RPAS‐based high spatial resolution RGB image is capable of predicting both physical and chemical ecosystem traits for alpine grasslands on the TP. Remote sensing on physical traits are overall more efficient than on chemical traits, with the highest R2 of 0.86 and 0.48 for physical trait and chemical one, respectively. The bands of Red and Green contributed more to the prediction model than band of Blue did, and the spectral mean value played a greater role than the spectral standard deviation. Based on the retrieved results, a set of spatial patterns on ecosystem traits can be revealed. This study represents an advance on ecosystem trait study and can significantly improve our understanding on ecosystem functions of the alpine ecosystem on the TP. [ABSTRACT FROM AUTHOR]

Aim: Precipitation manipulation experiments have shown diverse terrestrial carbon (C) cycling responses when the ecosystem is subjected to different magnitudes of altered precipitation, various experimental durations or heterogeneity in local climate. However, how these factors combine to affect C cycle responses to changes in precipitation remains unclear. Location: Global. Time period: 1990–2019. Major taxa studied: Terrestrial ecosystems. Methods: Using observations from 230 published studies in which precipitation was manipulated and terrestrial C cycling variables were measured, we conducted a global meta‐analysis to investigate responses of diverse C cycle processes to altered precipitation, including gross ecosystem productivity, ecosystem respiration, net ecosystem productivity, ecosystem carbon use efficiency, net primary productivity (NPP), aboveground and belowground NPP, aboveground and belowground biomass, shoot‐to‐root ratio, soil respiration and soil microbial biomass C. Results: We found that C cycling responses were correlated linearly and positively with the magnitude of precipitation treatments. We also detected that the responses of NPP and its aboveground component (ANPP) to altered precipitation weakened with experimental duration. Furthermore, gross ecosystem productivity, ecosystem respiration and net ecosystem productivity showed larger responses to precipitation treatments of greater magnitude over shorter time periods. The response of soil respiration, a key component of the C budget in most terrestrial ecosystems, depended in particular on the local climate. Local temperature and precipitation not only influenced the magnitude of the response of soil respiration to altered precipitation but also affected its sensitivity to the magnitude of the precipitation treatments, with higher sensitivities in the response of soil respiration to treatment magnitude at drier and colder sites. Main conclusions: Our findings highlight the importance of the interactions between the magnitude of precipitation treatments, their duration and the local climate in the response of ecosystem C cycling to altered precipitation, which is crucial to a better understanding of ecosystem C processes and functioning and projecting them under changing precipitation regimes. [ABSTRACT FROM AUTHOR]

Summary: Whether and how warming alters functional traits of absorptive plant roots remains to be answered across the globe. Tackling this question is crucial to better understanding terrestrial responses to climate change as fine‐root traits drive many ecosystem processes.We carried out a detailed synthesis of fine‐root trait responses to experimental warming by performing a meta‐analysis of 964 paired observations from 177 publications.Warming increased fine‐root biomass, production, respiration and nitrogen concentration as well as decreased root carbon : nitrogen ratio and nonstructural carbohydrates. Warming effects on fine‐root biomass decreased with greater warming magnitude, especially in short‐term experiments. Furthermore, the positive effect of warming on fine‐root biomass was strongest in deeper soil horizons and in colder and drier regions. Total fine‐root length, morphology, mortality, life span and turnover were unresponsive to warming.Our results highlight the significant changes in fine‐root traits in response to warming as well as the importance of warming magnitude and duration in understanding fine‐root responses. These changes have strong implications for global soil carbon stocks in a warmer world associated with increased root‐derived carbon inputs into deeper soil horizons and increases in fine‐root respiration. [ABSTRACT FROM AUTHOR]

Nitrogen immobilization usually leads to nitrogen retention in soil and, thus, influences soil nitrogen supply for plant growth. Understanding soil nitrogen immobilization is important for predicting soil nitrogen cycling under anthropogenic activities and climate changes. However, the global patterns and drivers of soil nitrogen immobilization remain unclear. We synthesized 1350 observations of gross soil nitrogen immobilization rate (NIR) from 97 articles to identify patterns and drivers of NIR. The global mean NIR was 8.77 ± 1.01 mg N kg−1 soil day−1. It was 5.55 ± 0.41 mg N kg−1 soil day−1 in croplands, 15.74 ± 3.02 mg N kg−1 soil day−1 in wetlands, and 15.26 ± 2.98 mg N kg−1 soil day−1 in forests. The NIR increased with mean annual temperature, precipitation, soil moisture, soil organic carbon, total nitrogen, dissolved organic nitrogen, ammonium, nitrate, phosphorus, and microbial biomass carbon. But it decreased with soil pH. The results of structural equation models showed that soil microbial biomass carbon was a pivotal driver of NIR, because temperature, total soil nitrogen, and soil pH mostly indirectly influenced NIR via changing soil microbial biomass. Moreover, microbial biomass carbon accounted for most of the variations in NIR among all direct relationships. Furthermore, the efficiency of transforming the immobilized nitrogen to microbial biomass nitrogen was lower in croplands than in natural ecosystems (i.e., forests, grasslands, and wetlands). These findings suggested that soil nitrogen retention may decrease under the land use change from forests or wetlands to croplands, but NIR was expected to increase due to increased microbial biomass under global warming. The identified patterns and drivers of soil nitrogen immobilization in this study are crucial to project the changes in soil nitrogen retention. [ABSTRACT FROM AUTHOR]

In contrast to existing methods that add specific substances to poly(l‐lactic acid)/poly(d‐lactic acid) racemic blends to enhance stereocomplexation, in this study, a crosslinkable epoxy resin (EP) was introduced into a racemic blend. The results showed that, when the mass ratio of EP to racemic blend was 0.2:1 (EP:racemic blend = 0.2), regardless of the amount of diethylenetriamine (DETA) curing agent, homo‐crystals in the racemic blend were essentially inhibited. With a fixed EP content, a 0.05:1 DETA to EP mass ratio resulted in a homogeneous poly(l‐lactic acid)/poly(d‐lactic acid)/EP/DETA mixture. Uniformly dispersed EP network promoted the stereocomplexation of the racemic blend from the melt, but delayed the lamellar thickening of the stereocomplex crystals during heating. Thus, the constrained chain diffusion caused by the uniformly dispersed EP network was likely responsible for these contradictory results. Introducing uniformly dispersed network into poly(l‐lactic acid)/poly(d‐lactic acid) racemic blends is presumably a promising approach for gaining more insight into poly(lactic acid) stereocomplexation. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

To make waterborne painting be applied into metal protection area, the mechanical, water resistant, and anti‐corrosion properties of the dried coating based on it should be improved effectively. Among various methods, self‐crosslinking the latex during its drying process is thought to be an effective way. For example, the latex with DAAM/ADH (diacetoneacrylamide/adipoyl hydrazide) as the self‐crosslinker has attracted a lot of attention due to its excellent stability and coating performance. In this study, a kind of reactable AIEgen was used and taken part in synthesizing the self‐crosslinkable acrylic latex. Based on Aggregation Induced Emission(AIE) phenomenon, it is easy to real‐time trace the preparation and curing process of the obtained latexes. At the same time, the influence of DAAM/ADH on the properties of the cured coating was studied in detail. In addition, as AIEgen is knitted onto the polymer chains via chemical bonds, external stimulus might interfere the coating's fluorescent property. Based on this phenomenon, the cured coating was studied and explored the feasibility to be applied into gas sensing area via its fluorescent property. [ABSTRACT FROM AUTHOR]

Soil nitrogen (N) transformations, which regulate soil N availability, are important for ecosystem productivity and other functions. Nitrogen deposition influences soil N transformations, but it remains unclear how soil N transformations, especially microbial N immobilization, change with different N deposition rates. In this study, we compiled a global data set of gross N mineralization, nitrification, and microbial mineral N immobilization rates with different N addition treatments across terrestrial ecosystems to reveal their responses to different N deposition rates. The results showed that gross N mineralization and gross nitrification rates were stimulated by both low and high N additions, but the increments slightly decreased with increasing N addition rate. However, microbial ammonium (NH4+) and nitrate (NO3−) immobilization rates responded differently under low versus high N additions. They changed from being inhibited (NH4+ immobilization) or not affected (NO3− immobilization) under low N addition to being stimulated under high N addition (>55 kg N ha−1 yr−1), performing a linear increase along with the increasing N addition rate. This challenges the traditional perception that N enrichment limits microbial N utilization. Our results suggest that the effects of N deposition on gross N transformations are highly dependent on N deposition rate. These findings indicate that biogeochemical models should take into account the differential responses of gross N transformations to different N addition rates to better predict ecosystem N cycling in the context of increasing N deposition. Key Points: Responses of gross N transformation rates to N deposition depended on N deposition rateLow N deposition stimulated gross N mineralization and nitrification and inhibited NH4+ immobilizationHigh N deposition stimulated gross N mineralization, nitrification, and NH4+ and NO3− immobilization [ABSTRACT FROM AUTHOR]

Soil nitrification, an important pathway of nitrogen transformation in ecosystems, produces soil nitrate that influences net primary productivity, while the by‐product of nitrification, nitrous oxide, is a significant greenhouse gas. Although there have been many studies addressing the microbiology, physiology, and impacting environment factors of soil nitrification at local scales, there are very few studies on soil nitrification rate over large scales. We conducted a global synthesis on the patterns and controlling factors of soil nitrification rate normalized at 25°C by compiling 3,140 observations from 186 published articles across terrestrial ecosystems. Soil nitrification rate tended to decrease with increasing latitude, especially in the Northern Hemisphere, and varied largely with ecosystem types. The soil nitrification rate significantly increased with mean annual temperature (MAT), soil nitrogen content, microbial biomass carbon and nitrogen, soil ammonium, and soil pH, but decreased with soil carbon:nitrogen and carbon:nitrogen of microbial biomass. The total soil nitrogen content contributed the most to the variations of global soil nitrification rate (total coefficient = 0.29) in structural equation models. The microbial biomass nitrogen (MBN; total coefficient = 0.19) was nearly of equivalent importance relative to MAT (total coefficient = 0.25) and soil pH (total coefficient = 0.24) in determining soil nitrification rate, while soil nitrogen and pH influenced soil nitrification via changing soil MBN. Moreover, the emission of soil nitrous oxide was positively related to soil nitrification rate at a global scale. This synthesis will advance our current understanding on the mechanisms underlying large‐scale variations of soil nitrification and benefit the biogeochemical models in simulating global nitrogen cycling. [ABSTRACT FROM AUTHOR]

Disentangling the relative response sensitivity of soil autotrophic (Ra) and heterotrophic respiration (Rh) to nitrogen (N) enrichment is pivotal for evaluating soil carbon (C) storage and stability in the scenario of intensified N deposition. However, the mechanisms underlying differential sensitivities of Ra and Rh and relative contribution of Rh to soil respiration (Rs) with increasing N deposition remain elusive.A manipulative field experiment with multi‐level N addition rates was conducted over 3 years (2015–2017) in an alpine meadow to explore the relative impact of N enrichment on Ra and Rh and the response of Rh/Rs ratio to the gradient of N addition.Soil respiration components had different sensitivities to N enrichment, with Ra decreasing more than Rh, leading to a higher Rh/Rs ratio as a function of increasing N addition rates. Ra and Rh decreased nonlinearly as N addition rates increased, with a critical load of 8 g N m−2 year−1 above which N enrichment significantly inhibited them. Ra and Rh were controlled by different abiotic and biotic factors, and the regulation of controlling factors on soil respiration components varied over time. N‐induced reduction in the relative abundance of forb significantly affected Ra, and this effect was mainly evident in the second and third years. Nitrogen enrichment significantly changed Rh in the third year, and the decreased Rh under high doses of N addition could be attributed to the changes in microbial biomass C, soil substrate quality and microbial composition.Our study highlights the leading role of Ra in regulating Rs responses to N enrichment and the enhancement of Rh/Rs ratio with increasing N addition. We also emphasize that N‐induced shifts in plant community composition play a vital role in regulating Ra instead of Rh. The changing drivers of Ra and Rh with time suggests that long‐term experiments with multiple levels of N addition are further needed to test the nonlinear responses and underlying mechanisms of soil respiration components in face to aggravating N deposition. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Summary: Plant RNA virus‐based guide RNA (gRNA) delivery has substantial advantages compared to that of the conventional constitutive promoter‐driven expression due to the rapid and robust amplification of gRNAs during virus replication and movement. To date, virus‐induced genome editing tools have not been developed for wheat and maize. In this study, we engineered a barley stripe mosaic virus (BSMV)‐based gRNA delivery system for clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9‐mediated targeted mutagenesis in wheat and maize. BSMV‐based delivery of single gRNAs for targeted mutagenesis was first validated in Nicotiana benthamiana. To extend this work, we transformed wheat and maize with the Cas9 nuclease gene and selected the wheat TaGASR7 and maize ZmTMS5 genes as targets to assess the feasibility and efficiency of BSMV‐mediated mutagenesis. Positive targeted mutagenesis of the TaGASR7 and ZmTMS5 genes was achieved for wheat and maize with efficiencies of up to 78% and 48%. Our results provide a useful tool for fast and efficient delivery of gRNAs into economically important crops. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) deposition have increased rapidly during the past decades, which likely changes soil N and P availability. These soil resource variations will further affect N, P concentration and N:P ratio in different ecosystem pools (i.e., soil, leaf, litter, root, and microbe). Various pools may show different stoichiometric responses to nutrient enrichment, with a further influence on ecosystem nutrient cycling. However, few studies have been conducted to fully examine the stoichiometric responses of different pools and their nutrient relationships in a given ecosystem. Here we established a 2‐year experiment of N (10 g m−2 year−1), P (10 g m−2 year−1), and combined N + P addition in a temperate forest of Changbai Mountain. We found significantly different N:P stoichiometric responses among various ecosystem components under P addition, with the leaves showing a higher response than litter and root while microbe behaving the lowest response. The responses of N:P ratio to N + P addition were similar with those under P addition in all pools. In most cases, N addition did not significantly affect N:P ratio. These results indicate that N:P ratio response was mainly determined by changes in P rather than N concentration in this temperate forest ecosystem. Moreover, we found tighter N:P stoichiometric correlations than elements among diverse ecosystem components under nutrient addition. Overall, our research reveals different responses and tight links of element stoichiometric variations among various ecosystem components in face of nutrient enrichment. It calls our attention to considering stoichiometric changes in the whole ecosystem beyond individual plant organ or microbial component. Key Points: Our goal is to compare and explore N:P responses and links among ecosystem components under nutrient enrichment in a temperate forestWe found different N:P responses in ecosystem components and their N:P relationships between each other under nutrient additionOur results provide new insights into understanding stoichiometric variations in a whole ecosystem view [ABSTRACT FROM AUTHOR]

Aim: Root turnover is an important process determining carbon and nutrient cycling in terrestrial ecosystems. It is an established fact that root turnover is jointly regulated by climatic, edaphic and biotic factors. However, the relative importance of these forces in determining the global patterns of root turnover time is far from clear. Location: Global. Time period: 1946–2017. Major taxa studied: Grasslands. Methods: We compiled a database of 141 sites with 433 observations on root turnover time and applied structural equation modelling (SEM) to investigate the relative contribution of climate, soil properties and vegetation type to the observed variations in root turnover time. Results: Root turnover time was 3.1 years on average across the global grasslands and differed significantly among grassland types (tropical grassland and savanna, temperate grassland and meadow, alpine grassland and meadow, tundra and desert). It decreased with mean annual temperature, mean annual precipitation and Palmer drought severity index but increased with soil organic carbon content, total nitrogen content and carbon : nitrogen ratio. Soil bulk density and soil texture also significantly affected root turnover time, with clay content negatively correlating to root turnover time and explaining more variations than bulk density and sand content. The SEM showed that climatic factors had dominant effects on root turnover time when vegetation type was not considered. Vegetation type became the primary driver when it was included in the SEM. Main conclusions: Our results indicate that the influences of climatic and edaphic factors on root turnover time are predominantly manifested through vegetation type. The critical role of precipitation as revealed for the first time in this study challenges our current understanding of climate impacts on root turnover time. The findings necessitate accurate representation of vegetation type in Earth system models to predict root function dynamics under global change. [ABSTRACT FROM AUTHOR]

Soil net nitrogen mineralization rate (Nmin), which is critical for soil nitrogen availability and plant growth, is thought to be primarily controlled by climate and soil physical and/or chemical properties. However, the role of microbes on regulating soil Nmin has not been evaluated on the global scale. By compiling 1565 observational data points of potential net Nmin from 198 published studies across terrestrial ecosystems, we found that Nmin significantly increased with soil microbial biomass, total nitrogen, and mean annual precipitation, but decreased with soil pH. The variation of Nmin was ascribed predominantly to soil microbial biomass on global and biome scales. Mean annual precipitation, soil pH, and total soil nitrogen significantly influenced Nmin through soil microbes. The structural equation models (SEM) showed that soil substrates were the main factors controlling Nmin when microbial biomass was excluded. Microbe became the primary driver when it was included in SEM analysis. SEM with soil microbial biomass improved the Nmin prediction by 19% in comparison with that devoid of soil microbial biomass. The changes in Nmin contributed the most to global soil NH4+‐N variations in contrast to climate and soil properties. This study reveals the complex interactions of climate, soil properties, and microbes on Nmin and highlights the importance of soil microbial biomass in determining Nmin and nitrogen availability across the globe. The findings necessitate accurate representation of microbes in Earth system models to better predict nitrogen cycle under global change. This study provides a comprehensive evaluation of the determinants of global Nmin with a focus on soil microbial biomass. The results demonstrated that soil microbial biomass predominantly controlled the variability of Nmin at a global scale. Climate, soil properties, and substrates influenced Nmin via their impacts on soil microbial biomass. The study highlights the importance of microbial biomass in determining soil nitrogen cycling, which challenges the conventional view that climate and soil properties are the dominant drivers of soil Nmin and advances our current understanding on the global patterns of nitrogen cycle. The findings suggest that changes in soil microbial biomass under global change would result in profound consequences on ecosystem processes by changing soil Nmin. [ABSTRACT FROM AUTHOR]

In order to explore the origin of the higher melting point of poly(lactic acid) (PLA) stereocomplex crystal (SC) than that of homo‐crystal (HC), the equilibrium melting point (Tm0) differential between SC and HC was determined using the Hoffman–Weeks method. The results showed that, for PLA samples with Mn around 16, 20 and 65 kg mol−1, the Tm0 differential between SC and HC is around 36, 42 and 55 °C, respectively. Thus, the higher melting point of SC compared to HC does not stem from Tm0 differential only. For PLA samples with lower Mn, the supercooling differential between poly(l‐lactic acid) (PLLA)/poly(d‐lactic acid) (PDLA) blends and PLLA is smaller than that with higher Mn, which means chain diffusion behavior is crucial for SC formation in PLLA/PDLA blends. The fact that the SC adopts the intermolecular parallel arrangement rather than the adjacent chain folding is verified by the greater slope of the melting point of SC versus crystallization temperature fitting curve when Mn is relative higher. © 2018 Society of Chemical Industry The figure shows that the smaller the Mn, the smaller the Tm0 differential between stereocomplex crystal and homo‐crystal. This suggests that the higher melting point of stereocomplex crystal does not stem from Tm0 differential only. [ABSTRACT FROM AUTHOR]

In this communication, we reported the sequence variation of stereocomplex crystals (SC) and homocrystals (HC) in poly(l‐lactic acid)/poly(d‐lactic acid) (PLLA/PDLA) racemic blends melts. It was evidenced that the emerging sequence of the SC and HC depends on the hydrogen bond formation in the melt, and the hydrogen bond is required for the stereocomplexation in PLLA/PDLA racemic blend. First, by combining a commercial fast‐scan chip‐calorimeter (Flash DSC 1) and micro‐FTIR, we found that hydrogen bonds were formed in the melt during cooling at 2.5 K/s, but not at 3000 K/s. Second, annealing the melt without hydrogen bonds at 100 °C led to HC emerging first, while annealing the melt with hydrogen bonds resulted in SC emerging at first. Third, the crystallization kinetics of the racemic blends after cooling to predefined Tc at 2.5 or 3000 K/s further verified that the hydrogen bonding can be inhibited effectively by cooling the racemic blends isotropic melt at fast enough rate. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 83–88 Hydrogen bonds between the enantiomers were formed when the isotropic melt of poly(L‐lactic acid)/poly(D‐lactic acid) racemic blends was cooled at 2.5 K/s. However, no hydrogen bond formation was detected at a cooling rate of 3000 K/s. In the presence of hydrogen bonds, stereocomplex crystals (SC) emerged first. On the contrary, without hydrogen bonds in the melt of racemic blends, homocrystals (HC) emerged first at the annealing temperature of 100 °C. [ABSTRACT FROM AUTHOR]

Preventing soil biological degradation under the cultivation of Bacillus thuringiensis (Bt) crops is crucial to soil health. Despite studies concerning environmental risks of Bt crops, we surprisingly know little about whether soil biological degradation occurs under Bt crop cultivations. To fill this gap, we calculated the index of resistance (IR) and resilience (IR′) of 13 soil properties (the activities of enzymes, the rates of ecosystem processes, soil microbial biomass, and soil carbon and nutrients) using soil samples collected from an 8‐year Bt rice cultivation experiment, including three treatments, that is, continual cultivation of Bt rice (GM) and non‐Bt rice (non‐GM), and rotation between Bt and non‐Bt rice every 2 years (GM/non‐GM rotation). In GM and GM/non‐GM rotation, the IR of the activities of dehydrogenase, acid phosphatase, methane production rates was significantly greater than that in non‐GM. Further, the IR of denitrification, methane oxidation, microbial carbon, and microbial nitrogen was significantly lowered in GM, and the IR of microbial carbon in GM/non‐GM rotation was significantly decreased compared with that in non‐GM. However, the results of IR′ showed no significant differences in these soil properties between treatments, except for methane oxidation and urease in GM and microbial nitrogen in GM/non‐GM rotation. Taking into consideration of soil resistance and resilience, the most soil properties remained relatively stable. These findings suggest that the Bt rice cultivations have not significantly resulted in soil biological degradation. [ABSTRACT FROM AUTHOR]

Transforming cropland into a semi‐natural ecosystem is an effective approach to increase soil organic carbon (SOC) and nitrogen sequestration. However, we know little about large‐scale response patterns of SOC, soil inorganic nitrogen (SIN), and their interactions over long time of ecosystem restoration. Here, we conducted a meta‐analysis to examine changes in SOC, SIN, and their relationship along 50 year's ecosystem development from cropland transformation in China's 'Grain for Green' Programme. Our results showed that SOC and SIN were consistently enhanced by 57% and 35% with transformation, respectively. Similar with SOC, SIN had higher response magnitudes when cropland was restored to forests (47%) than to shrublands (36%) and grasslands (24%). Both SOC and SIN response ratios showed a quadratic relationship with precipitation. Moreover, we found a strong linear relationship (R2 = 0.36) between SOC and SIN response ratio, with the slope indicating a 0.43% increase in SIN per 1% of increasing SOC. This SIN retention capacity (the slope) significantly increased with restoration time but reduced with precipitation, temperature, and initial SOC. Restored forest had a lower SIN retention capacity than had shrubland and grassland. Overall, this study represents the first to regionally uncover SIN retention mechanism with increasing SOC during ecosystem development. It suggests that ecosystem restoration will contribute more to relieving serious environmental problems (i.e., N leaching and N2O emission) by enhancing SIN retention in China's Grain for Green Programme. [ABSTRACT FROM AUTHOR]

Abstract: Polyamide 6 and aliphatic polyketone exhibit similar melting points and heats of fusion, which expose the kinetic effects of intermolecular interactions on their crystallization kinetics. The commercial chip‐calorimeter Flash DSC1 is employed to measure their crystallization rates in a broad temperature range. The results show that polyamide crystallizes faster than polyketone at high temperatures, but slower at low temperatures. The faster crystallization is attributed to a lower lateral‐surface free energy for crystal nucleation at high temperatures on account of the sheet‐like hydrogen bonding in polyamide crystals. The slower crystallization is attributed to the lower molecular mobility for crystal nucleation at low temperatures on account of the higher glass transition temperature of polyamide. [ABSTRACT FROM AUTHOR]

By using a commercial fast-scan chip-calorimeter, the effect of molecular weight on the isothermal crystallization rates of linear and cyclic poly(epsilon-caprolactone) samples (L- PCLs and C- PCLs) is investigated. The results confirm the non-monotonic molecular weight dependence of the crystallization rates of both L- PCLs and C- PCLs over a wide temperature range, previously observed only in the high temperature range, in which the medium molecular weight PCLs exhibit the highest crystallization rate. Chain-end effects of L- PCL with medium molecular weights induce faster crystallization rates in specific low temperature regions, in comparison to that for counterpart C- PCL. This phenomenon no longer exists in high molecular weight samples because of 'diluted' chain-end effects in long chain samples. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Soil bacterial succession under intensive anthropogenic disturbances is not well known. Using terminal restriction fragment length polymorphisms and 454 pyrosequencing of 16S rRNA genes, this study investigated how soil bacterial diversity and community structure changed under two agricultural land uses (paddy rice and upland cropping) in relation to soil development along a 500-year chronosequence created by intermittent reclamation of estuarine salt marshes. Multivariate analysis revealed orderly changes in soil physicochemical properties and bacterial community structure with time, confirming the occurrence of soil development and bacterial succession. Patterns of soil development and bacterial succession resembled each other, with recent land uses affecting their trajectories but not the overall direction. Succession of bacterial community structure was mainly associated with changes in α- Proteobacteria and Verrucomicrobia. Two stages of bacterial succession were observed, a dramatic-succession stage during the first several decades when bacterial diversity increased evidently and bacterial community structure changed rapidly, and a long gradual-succession stage that lasted for centuries. Canonical correspondence analysis identified soil Na, potentially mineralizable nitrogen, total phosphorous, and crystallinity of iron oxyhydrates as potential environmental drivers of bacterial succession. To conclude, orderly succession of soil bacterial communities occurred along with the long-term development of agroecosystems, which in turn was associated with soil physicochemical changes over time. [ABSTRACT FROM AUTHOR]

Hybrid capacitive deionization (HCDI) emerges as a burgeoning electrochemical desalination technology due to the utilization of profitable pseudocapacitive reactions. Although tunable organic compounds are potential faradaic electrode materials, their insufficient active sites and high water‐solubility restrict practical HCDI applications. Herein, a pseudocapacitive organic polymer (PNDS) is proposed with diverse redox‐active sites for electrochemical deionization. The pronounced molecular aromaticity and strong π‐electron delocalization not only endow PNDS polymer with framework rigidity, but refine its electronic structure to bolster redox activity and electron affinity. As an electrode material, the PNDS polymer demonstrates a substantial pseudocapacitive capacitance of 390 F g−1 and sustains long‐term stability at 96.3% after 5000 cycles, surpassing reported Na+‐capturing organic electrodes. In‐operando monitoring techniques and theoretical calculations reveal efficient Na+ capture at the C═N and C═O redox‐active sites within the PNDS electrode during repeated electrosorption processes. As a conceptual demonstration, a high‐performance HCDI device equipped with the PNDS electrode exhibits an impressive salt removal capacity (66.4 mg g−1), a rapid removal rate (2.2 mg g−1 min−1) and stable regeneration property. More importantly, an integrated desalination system is engineered to rapidly and repeatedly treat saltwater resources for human consumption and agricultural irrigation, highlighting its promising prospects for high‐efficiency desalination applications. [ABSTRACT FROM AUTHOR]