Search

The bacteria that dominate and become enriched in the rhizosphere during continuous cropping are of increasing interest, as they can greatly adapt to the rhizosphere. However, there are still little knowledge about the general composition and function of these bacteria. In this study, we planted tomatoes in three different soils for three planting cycles and used both high-throughput sequencing and culture-dependent workflows. Despite significant differences in bacterial communities from the initial soils, we observed a similar succession in the rhizosphere bacterial community compositions. We identified certain bacteria that were gradually enriched and potentially beneficial, such as Rhizobium and Flavobacterium. However, some other potentially beneficial bacteria, such as Massilia and Lysobacter, were gradually depleted. Additionally, we found that predicted functions related to xenobiotic biodegradation, nutrient metabolism and antibiotic biosynthesis were enriched in different rhizosphere soils. Beijerinckia fluminensis GR2, which was gradually enriched in all tested soils, significantly inhibited the growth of Ralstonia solanacearum and protected the host from infection. Our study provides new insights into the assembly mechanism of gradually enriched bacteria and their role as plant-beneficial microbes that adapt well to the rhizosphere. [ABSTRACT FROM AUTHOR]

It is significant to detect the bridge from LiDAR automatically and quickly, which is regarded as an important artificial building and transport hub. In this paper, a skinny triangle-based detection algorithm of bridge over water is proposed. First, Triangulated Irregular Network(TIN) is generated in LiDAR data, during which a skinny triangle is used to detect points on the river edge and bridge, and the elevation difference between them is used to separate those points. Second, a nonlinear classifier designed with TIN is used to separate the LiDAR points on the river edge. Points of bridge borders can be separated automatically and adaptively according to the collinear characteristics of the bridge border. Finally, creating fitted curves to obtain river bank and bridges borders respectively. The coordinate of bridge angular points can be obtained by solving the equations set, which is consists of the river bank curve and bridges borders curve simultaneous. The experimental results demonstrate that the proposed algorithm can perform well to extract bridge over water from LiDAR data. [ABSTRACT FROM AUTHOR]

High-throughput sequencing, culture-dependent workflows, and microbiome transfer experiments reveal whether potassium phosphite (KP), an environmentally acceptable agricultural chemical, could specifically enrich the antagonistic bacterial community that inhibited the growth of the pathogen Ralstonia solanacearum. The application of KP enriched the potential antagonistic bacteria Paenibacillus and Streptomyces in soil, but depleted most dominant genera belonging to gram negative bacteria, such as Pseudomonas, Massilia, and Flavobacterium on day 7. Moreover, the KP-modulated soil microbiome suppressed R. solanacearum growth in soil. The predicted functions related to the synthesis of antagonistic substances, such as streptomycin, and the predicted functions related to tellurite resistance and nickel transport system were significantly enriched, but the synthesis of lipopolysaccharide (distinct component lipopolysaccharide in gram negative bacteria) were significantly depleted in the KP-treated soils. In addition, the copy numbers of specific sequences for Streptomyces coelicoflavus and Paenibacillus favisporus were significantly increased in the soil amended with KP, inhibited the growth of R. solanacearum, and had a higher tolerance of KP than R. solanacearum. Our study linked the application of fertilizers to the enrichment of antagonistic bacteria, which could support future work that aims to precisely regulate the soil microbiome to protect the host from infection by soil-borne pathogens. [ABSTRACT FROM AUTHOR]

Phenolic acids are mainly released from plant residue decomposition and play important roles in the assembly of the soil microbiome. Understanding the general features of soil microbial communities modulated by phenolic acids could provide fundamental insights into the assembly of the soil microbiome. We analyzed the effects of four phenolic acids (ferulic acid, phthalic acid, salicylic acid and tannic acid) on the soil fungal communities at two concentrations. Despite the application of different phenolic acids to the soil, we were able to identify certain general changes in the fungal communities. We found that the tested phenolic acids significantly increased the deterministic assembly process of the fungal community but decreased the fungal diversity. Moreover, the fungal community structure under each tested phenolic acid treatment was distinct at low concentrations but similar at high concentrations. Salicylic acid had the greatest impacts on the fungal community. In addition, Fusarium and Aspergillus were significantly enriched in the soil amended with all the tested phenolic acids at high concentrations. Our study revealed certain general changes in the soil fungal communities modulated by phenolic acids, which deepened our understanding of the fungal assembly mechanism and provided robust insights for identifying candidate phenolic acid-degrading microbes. [ABSTRACT FROM AUTHOR]

The influence of fertilization on crop nutrient use efficiency (NUE) and productivity remain unclear. Here, to assess how fertilization management influences the soil microbial communities and their functional profiles and consequently affects NUE and crop productivity, we established a field experiment with mineral and combined organic-mineral fertilization as well as mineral fertilizer reduction practices. The composition of the microbial community was measured by high-throughput amplicon sequencing, and its functional profile was predicted using PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) software. Our results demonstrated that fertilization management significantly shifted the rhizosphere bacterial community and regulated the compensation intensity of nutrient cycling-related functions, which means the rhizosphere bacterial community assembles to harbour greater nutrient cycling-related functions in lower available nutrient conditions to meet the nutrient requirements of the host plant. Moderate compensation intensity of nutrient cycling functions contributed to the highest NUE and crop productivity being achieved in the combined organic-mineral fertilization treatment. However, insufficient fertilizer input induced intense functional compensation, while standard mineral fertilizer input resulted in weakened functional compensation of nutrient cycling functions, both of which decreased NUE and crop productivity. Overall, this study provides new insights into the key roles of the rhizosphere microbiome in improving NUE, and suggests that the functional compensation characteristics of the rhizosphere microbial community may be a sensitive indicator of nutrient supply and demand relationships as well as a predictor of NUE. • Fertilization alters the compensation intensity of rhizospheric nutrient cycling functions. • Moderate compensation of nutrient cycling functions triggers high nutrient use efficiency (NUE). • Both intensified and marginalized functional compensation decrease the NUE. [ABSTRACT FROM AUTHOR]

Understanding the interactions between beneficial bacteria, plant pathogens, and root exudates is necessary for the optimization of the bio-control strategies targeted toward plant soil-borne diseases. In this study, we showed that the competitive use of root exudates by the antagonistic bacterial strain SQYUV 162 along with the pathogenic strain Ralstonia solanacearum affected the pathogenic population density and the pathogenicity of R. solanacearum . All of the tested organic acids induced chemotaxis in both SQYUV 162 and R. solanacearum . In addition, the growth of both SQYUV 162 and R. solanacearum was affected by the addition of organic acids. Strong chemotactic responses in SQYUV 162 and R. solanacearum were induced by malic acid and citric acid respectively. It was also observed that the addition of organic acids significantly induced the expression of several virulence-related genes and increased the population density of the pathogen on the roots, resulting in higher disease incidences in hydroponic experiments in comparison to a control. When SQYUV 162 was inoculated, however, both the expression of virulence-related genes and the population density of the pathogen decreased. The population density of SQYUV 162 also increased when roots were placed in contact with organic acids. The improved colonization density of SQYUV 162, as well as the decreased pathogenicity and population density of the pathogen, efficiently suppressed the incidence of bacterial wilt. The present results indicate that certain components of root exudates could suppress soil-borne diseases: by applying bacteria whose resource consumption profile overlaps that of plant pathogens, plant diseases may be better controlled. [ABSTRACT FROM AUTHOR]

An efficient synthesis of 2-amino-3-methylenephthalimide through palladium-catalyzed intramolecular aminocarbonylation has been developed. The reaction carried out under atmospheric pressure of CO and provided diversified 2-amino-3-methylenephthalimides in reasonable to good yields from o-iodoacetophenone phenylhydrazone, which are readily derived from phenylhydrazines and 2-iodoacetophenones. [ABSTRACT FROM AUTHOR]

Summary: Rhizomicrobiome plays important roles in plant growth and health, contributing to the sustainable development of agriculture. Plants recruit and assemble the rhizomicrobiome to satisfy their functional requirements, which is widely recognized as the 'cry for help' theory, but the intrinsic mechanisms are still limited.In this study, we revealed a novel mechanism by which plants reprogram the functional expression of inhabited rhizobacteria, in addition to the de novo recruitment of soil microbes, to satisfy different functional requirements as plants grow. This might be an efficient and low‐cost strategy and a substantial extension to the rhizomicrobiome recruitment theory.We found that the plant regulated the sequential expression of genes related to biocontrol and plant growth promotion in two well‐studied rhizobacteria Bacillus velezensis SQR9 and Pseudomonas protegens CHA0 through root exudate succession across the plant developmental stages. Sixteen key chemicals in root exudates were identified to significantly regulate the rhizobacterial functional gene expression by high‐throughput qPCR.This study not only deepens our understanding of the interaction between the plant–rhizosphere microbiome, but also provides a novel strategy to regulate and balance the different functional expression of the rhizomicrobiome to improve plant health and growth. [ABSTRACT FROM AUTHOR]

Based on the mode-coupling method, numerical analysis is presented to demonstrate the influence of ripple taper on coupling modes on the frequency response in a coaxial Bragg structure. Results show that the interval between the band-gaps of the competing mode and the desired working mode is narrowed by use of a positive taper, but is expanded if a negative taper is employed, and the influence of the negative taper is more obviously advantage than the positive taper. The residual side-lobes of the frequency response on coupling modes can be effectively suppressed by employing the windowing-function technique. These characteristics of a tapered coaxial Bragg structure are favorable to improvement of the performance as a reflector or a filter in its application, also favorable to the mode selectivity and further weaken the excitation of unwanted spurious modes. [ABSTRACT FROM AUTHOR]

Background: Brain-derived estrogen is implicated in pain-related aversion; however, which estrogen receptors mediate this effect remains unclear. This study hypothesized that the different estrogen receptors in the rostral anterior cingulate cortex play distinct roles in pain-related aversion.Methods: Formalin-induced conditioned place avoidance and place escape/avoidance paradigms were used to evaluate pain-related aversion in rodents. Immunohistochemistry and Western blotting were used to detect estrogen receptor expression. Patch-clamp recordings were used to examine N-methyl-D-aspartate-mediated excitatory postsynaptic currents in rostral anterior cingulate cortex slices.Results: The administration of the estrogen receptor-β antagonist 4-(2-phenyl-5,7-bis [trifluoromethyl] pyrazolo [1,5-a] pyrimidin-3-yl) phenol (PHTPP) or the G protein-coupled estrogen receptor-1 antagonist (3aS*,4R*,9bR*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta [c] quinolone (G15) but not the estrogen receptor-α antagonist 1,3-bis (4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy) phenol]-1H-pyrazole dihydrochloride (MPP) into the rostral anterior cingulate cortex blocked pain-related aversion in rats (avoidance score, mean ± SD: 1,3-bis [4-hydroxyphenyl]-4-methyl-5-(4-[2-piperidinylethoxy] phenol)-1H-pyrazole dihydrochloride (MPP): 47.0 ± 18.9%, 4-(2-phenyl-5,7-bis [trifluoromethyl] pyrazolo [1,5-a] pyrimidin-3-yl) phenol (PHTPP): -7.4 ± 20.6%, and [3aS*,4R*,9bR*]-4-[6-bromo-1,3-benzodioxol-5-yl]-3a,4,5,9b-3H-cyclopenta [c] quinolone (G15): -4.6 ± 17.0% vs. vehicle: 46.5 ± 12.2%; n = 7 to 9; P < 0.0001). Consistently, estrogen receptor-β knockdown but not estrogen receptor-α knockdown by short-hairpin RNA also inhibited pain-related aversion in mice (avoidance score, mean ± SD: estrogen receptor-α-short-hairpin RNA: 26.0 ± 7.1% and estrogen receptor-β-short-hairpin RNA: 6.3 ± 13.4% vs. control short-hairpin RNA: 29.1 ± 9.1%; n = 7 to 10; P < 0.0001). Furthermore, the direct administration of the estrogen receptor-β agonist 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN) or the G protein-coupled estrogen receptor-1 agonist (±)-1-([3aR*,4S*,9bS*]-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta [c]quinolin-8-yl)-ethanone (G1) into the rostral anterior cingulate cortex resulted in conditioned place avoidance (avoidance score, mean ± SD: 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN): 35.3 ± 9.5% and (±)-1-([3aR*,4S*,9bS*]-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta [c]quinolin-8-yl)-ethanone (G1): 43.5 ± 22.8% vs. vehicle: 0.3 ± 14.9%; n = 8; P < 0.0001) but did not affect mechanical or thermal sensitivity. The activation of the estrogen receptor-β/protein kinase A or G protein-coupled estrogen receptor-1/protein kinase B pathway elicited the long-term potentiation of N-methyl-D-aspartate-mediated excitatory postsynaptic currents.Conclusions: These findings indicate that estrogen receptor-β and G protein-coupled estrogen receptor-1 but not estrogen receptor-α in the rostral anterior cingulate cortex contribute to pain-related aversion by modulating N-methyl-D-aspartate receptor-mediated excitatory synaptic transmission. [ABSTRACT FROM AUTHOR]

A high regioselective rhodium-catalyzed ortho C H coupling of 2-arylindoles with diazo compounds via NH-indole-directed C H bond activation has been developed. The catalytic reaction features mild reaction conditions, broad substrate scope and good functional group tolerability. [ABSTRACT FROM AUTHOR]

Abstract: In the past decades, C−H oxidative olefination of indole at C‐2, C‐3, C‐4 and C‐7 positions was well addressed. We report here a rhodium‐catalyzed NH‐indole‐directed ortho C−H bond olefination of 2‐arylindoles. This cross‐dehydrogenative‐coupling proved to be broad in substrate scope, tolerating a variety of functional groups. The synthesis of 6H‐isoindolo[2,1‐α]indoles via rhodium‐catalyzed ortho C−H olefination and subsequent intramolecular aza‐Michael reaction of 2‐arylindoles was also demonstrated. [ABSTRACT FROM AUTHOR]