Summary
Plant microbiomes are essential to host health and productivity but the ecological processes that govern crop microbiome assembly are not fully known.
Here we examined bacterial communities ...across 684 samples from soils (rhizosphere and bulk soil) and multiple compartment niches (rhizoplane, root endosphere, phylloplane, and leaf endosphere) in maize (Zea mays)‐wheat (Triticum aestivum)/barley (Hordeum vulgare) rotation system under different fertilization practices at two contrasting sites.
Our results demonstrate that microbiome assembly along the soil‐plant continuum is shaped predominantly by compartment niche and host species rather than by site or fertilization practice. From soils to epiphytes to endophytes, host selection pressure sequentially increased and bacterial diversity and network complexity consequently reduced, with the strongest host effect in leaf endosphere. Source tracking indicates that crop microbiome is mainly derived from soils and gradually enriched and filtered at different plant compartment niches. Moreover, crop microbiomes were dominated by a few dominant taxa (c. 0.5% of bacterial phylotypes), with bacilli identified as the important biomarker taxa for wheat and barley and Methylobacteriaceae for maize.
Our work provides comprehensive empirical evidence on host selection, potential sources and enrichment processes for crop microbiome assembly, and has important implications for future crop management and manipulation of crop microbiome for sustainable agriculture.
Agricultural food production is at the base of food and fodder, with fertilization having fundamentally and continuously increased crop yield over the last decades. The performance of crops is ...intimately tied to their microbiome as they together form holobionts. The importance of the microbiome for plant performance is, however, notoriously ignored in agricultural systems as fertilization disconnects the dependency of plants for often plant-beneficial microbial processes. Moreover, we lack a holistic understanding of how fertilization regimes affect the soil microbiome. Here, we examined the effect of a 2-year fertilization regime (no nitrogen fertilization control, nitrogen fertilization, and nitrogen fertilization plus straw amendment) on entire soil microbiomes (bacteria, fungi, and protist) in three common agricultural soil types cropped with maize in two seasons.
We found that the application of nitrogen fertilizers more strongly affected protist than bacterial and fungal communities. Nitrogen fertilization indirectly reduced protist diversity through changing abiotic properties and bacterial and fungal communities which differed between soil types and sampling seasons. Nitrogen fertilizer plus straw amendment had greater effects on soil physicochemical properties and microbiome diversity than nitrogen addition alone. Moreover, nitrogen fertilization, even more together with straw, increased soil microbiome network complexity, suggesting that the application of nitrogen fertilizers tightened soil microbiomes interactions.
Together, our results suggest that protists are the most susceptible microbiome component to the application of nitrogen fertilizers. As protist communities also exhibit the strongest seasonal dynamics, they serve as the most sensitive bioindicators of soil changes. Changes in protist communities might have long-term effects if some of the key protist hubs that govern microbiome complexities as top microbiome predators are altered. This study serves as the stepping stone to promote protists as promising agents in targeted microbiome engineering to help in reducing the dependency on exogenous unsustainably high fertilization and pesticide applications.
Summary
Plants harbour highly diverse mycobiomes which sustain essential functions for host health and productivity. However, ecological processes that govern the plant–mycobiome assembly, ...interactions and their impact on ecosystem functions remain poorly known. Here we characterized the ecological role and community assembly of both abundant and rare fungal taxa along the soil–plant continuums (rhizosphere, phyllosphere and endosphere) in the maize–wheat/barley rotation system under different fertilization practices at two contrasting sites. Our results indicate that mycobiome assembly is shaped predominantly by compartment niche and host species rather than by environmental factors. Moreover, crop‐associated fungal communities are dominated by few abundant taxa mainly belonging to Sordariomycetes and Dothideomycetes, while the majority of diversity within mycobiomes are represented by rare taxa. For plant compartments, the abundant sub‐community is mainly determined by stochastic processes. In contrast, the rare sub‐community is more sensitive to host selection and mainly governed by deterministic processes. Furthermore, our results demonstrate that rare taxa play an important role in fungal co‐occurrence network and ecosystem functioning like crop yield and soil enzyme activities. These results significantly advance our understanding of crop mycobiome assembly and highlight the key role of rare taxa in sustaining the stability of crop mycobiomes and ecosystem functions.
Summary
Viruses can affect microbial dynamics, metabolism and biogeochemical cycles in aquatic ecosystems. However, viral diversity and functions in agricultural soils are poorly known, especially in ...the rhizosphere. We used virome analysis of eight rhizosphere and bulk soils to study viral diversity and potential biogeochemical impacts in an agro‐ecosystem. The order Caudovirales was the predominant viral type in agricultural soils, with Siphoviridae being the most abundant family. Phylogenetic analysis of the terminase large subunit of Caudovirales identified high viral diversity and three novel groups. Viral community composition differed significantly between bulk and rhizosphere soils. Soil pH was the main environmental driver of the viral community structure. Remarkably, abundant auxiliary carbohydrate‐active enzyme (CAZyme) genes were detected in viromes, including glycoside hydrolases, carbohydrate esterases and carbohydrate‐binding modules. These results demonstrate that virus‐encoded putative auxiliary metabolic genes or metabolic genes that may change bacterial metabolism and indirectly contribute to biogeochemical cycling, especially carbon cycling, in agricultural soil.
Atropisomers bearing multiple stereogenic axes are of increasing importance to the field of material science, pharmaceuticals, and catalysis. However, the atroposelective construction of multi‐axis ...atropisomers remains rare and challenging, due to the intrinsical difficulties in the stereo‐control of the multiple stereogenic axes. Herein, we demonstrate a single‐step construction of a new class of 1,2‐diaxially chiral triaryl α‐pyranones by an N‐heterocyclic carbene organocatalytic asymmetric 3+3 annulation of well‐designed alkynyl acylazolium precursors and enolizable sterically hindered 2‐aryl ketones. The protocol features broad substrate scope (>50 examples), excellent stereo‐control (most cases >20 : 1 dr, up to 99.5 : 0.5 er), and potentially useful synthetic applications. The success of this reaction relies on the rational design of structurally matched reaction partners and the careful selection of the asymmetric catalytic system. DFT calculations have also been performed to discover and rationalize the origin of the high stereoselectivity of this reaction.
The single‐step atroposelective construction of triaryl α‐pyranones with stereogenic 1,2‐diaxes was accomplished by NHC organocatalysis. The structure of the substrates and the catalytic system play a critical role in the success of this protocol. DFT calculations were performed to rationalize the origin of the high stereoselectivity.
As a wearable device, highly sensitive and stretchable strain sensors should be integrated to monitor various daily actions, which include large- and small-scale strains, such as jumping, running, ...heartbeat, and pulse. At present, the method of preparing strain sensors is mainly to impregnate or load materials like graphene, carbon nanotube, and their union products on elastic substrates to obtain highly sensitive characteristics. Both well-known carbon-based and other single-dimensional nanomaterials do not have high flexibility and conductivity, which limits the improvement of sensitivity. However, a novel material MXene Ti3C2T x has a two-dimensional (2D) sheet structure, which allows for higher electron and ion transmission rates. In addition, it is easier to be combined with other nanomaterials as a nanosubstrate, greatly improving malleability. Hence, we creatively prepared zero-dimensional (0D)–one-dimensional (1D)–2D multi-dimensional nanomaterials, which designed 0D silver nanoparticles (AgNPs) loaded on 2D MXene nanosheets and compounded with 1D silver nanowires (AgNWs). The method improves the elasticity and conductivity of traditional single-dimensional materials, wherein AgNPs built a bridge between AgNWs and MXene, which ensures continuity and a high gauge factor even at a large strain (200%) of yarn. The composite yarn strain sensor has a remarkably high strain and sensitivity, effectively monitoring the large and small deformations of various parts of the human body, whose fabric can be an electrothermal device. It has vital inspiration for the development of intelligent textiles, which would be used in medical devices, artificial skin, and other wearable fields.
This article provides a framework of dead zone compensation and robust adaptive vibration control for uncertain spatial flexible riser systems. First, nonsymmetric dead zone nonlinearity is ...represented in the form of the desired control input with the addition of an extra nonlinear input error. Second, by visualizing those input errors and extrinsic disturbances as an unknown "disturbance-like" term, a new robust adaptive vibration control technology and online updating laws can be constructed for riser systems to guarantee the oscillation reduction and compensation of uncertainties and dead zone. Third, the constructed control ensures and achieves bounded Lyapunov stability in the controlled system. Ultimately, control performances are demonstrated with appropriate design parameters.
Despite the increasing resolution, forcing on the mean circulation by resolved waves in general circulation models is not yet converging. Parameterization of the forcing remains a major source of ...model uncertainty. This study examines the scale invariance of zonal spectra of momentum flux and wave forcing, and shows that it can be used to quantify the forcing by unresolved waves with knowledge of the resolved ones in global models. The result reveals the leading order importance of the small-scale wave forcing, which is in general agreement with that required for obtaining the zonal mean wind climatology. It is also found that wave and mean flow interaction is important in maintaining the robust spectral structure. This method may provide a strategy to design physically consistent and scale-aware parameterization schemes for scale invariant quantities, when a model has sufficient resolution to partially resolve their spectra.
The aim of this article is to establish a novel boundary antidisturbance control to dampen the oscillation of a spatially nonlinear flexible string system influenced by unknown disturbances. To ...realize this, new disturbance rejection controllers are constructed to effectively suppress the external disturbances for vibration reduction with the help of a newly designed disturbance observer. Adopting Lyapunov direct method, we ensure that the derived control system is uniformly bounded stable. Simulations are also performed to demonstrate the feasibility and validity of the suggested strategy.
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