Microbial volatile organic compounds 2-heptanol and acetoin control Fusarium crown and root rot of tomato.

Some microbial volatile organic compounds (mVOCs) can act as antagonistic weapons against plant pathogens, but little information is available on the contribution of individual mVOC to biocontrol and how they interact with plant pathogens. In this study, the Bacillus subtilis strain N-18 isolated from the rhizosphere of healthy plants grown in areas where Fusarium crown and root rot (FCRR) of tomato occurs could reduce the 30% of the incidence of FCRR. Moreover, the volatile organic compounds (VOCs) produced by N-18 had inhibitory effects on Fusarium oxysporum f. sp. radicis-lycopersici (FORL). The identification of VOCs of N-18 was analyzed by the solid-phase microextraction coupled to gas chromatography-mass spectrometry. Meanwhile, we conducted sensitivity tests with these potential active ingredients and found that the volatile substances acetoin and 2-heptanol can reduce the 41.33% and 35% of the incidence of FCRR in tomato plants. In addition, the potential target protein of acetoin, found in the cheminformatics and bioinformatics database, was F. oxysporum of hypothetical protein AU210_012600 (FUSOX). Molecular docking results further predicted that acetoin interacts with FUSOX protein. These results reveal the VOCs of N-18 and their active ingredients in response to FORL and provide a basis for further research on regulating and controlling FCRR.

Silica nanoparticles protect rice against biotic and abiotic stresses.

BACKGROUND: By 2050, the world population will increase to 10 billion which urged global demand for food production to double. Plant disease and land drought will make the situation more dire, and safer and environment-friendly materials are thus considered as a new countermeasure. The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice worldwide that seriously threatens rice production. Unfortunately, traditional breeding nor chemical approaches along control it well. Nowadays, nanotechnology stands as a new weapon against these mounting challenges and silica nanoparticles (SiO2 NPs) have been considered as potential new safer agrochemicals recently but the systematically studies remain limited, especially in rice. RESULTS: Salicylic acid (SA) is a key plant hormone essential for establishing plant resistance to several pathogens and its further affected a special form of induced resistance, the systemic acquired resistance (SAR), which considered as an important aspect of plant innate immunity from the locally induced disease resistance to the whole plant. Here we showed that SiO2 NPs could stimulate plant immunity to protect rice against M. oryzae through foliar treatment that significantly decreased disease severity by nearly 70% within an appropriate concentration range. Excessive concentration of foliar treatment led to disordered intake and abnormal SA responsive genes expressions which weaken the plant resistance and even aggravated the disease. Importantly, this SA-dependent fungal resistance could achieve better results with root treatment through a SAR manner with no phytotoxicity since the orderly and moderate absorption. What's more, root treatment with SiO2 NPs could also promote root development which was better to deal with drought. CONCLUSIONS: Taken together, our findings not only revealed SiO2 NPs as a potential effective and safe strategy to protect rice against biotic and abiotic stresses, but also identify root treatment for the appropriate application method since it seems not causing negative effects and even have promotion on root development.

Plant Endophytic Fungus Extract ZNC Improved Potato Immunity, Yield, and Quality.

Endophytic fungi play an important role in plant survival and reproduction, but the role of their metabolites in plant growth and immunity, as well as in crop quality formation, is poorly understood. Zhinengcong (ZNC) is a crude ethanol extract from the endophytic fungus Paecilomyces variotii, and previous studies have shown that it can improve the growth and immunity in Arabidopsis thaliana. The aim of the study was to reveal the trade-off balance between plant growth and immunity by evaluating the mechanisms of ZNC on potato growth, yield, and priming immunity against the oomycete Phytophthora infestans indoors and in the field. ZNC maintained a good balance between plant growth and resistance against P. infestans with high activity. It induced the reactive oxygen species (ROS) production, promoted plant growth, yield and quality parameters, enhanced the expression of indoleacetic acid (IAA) related genes, and increased the absorption of nitrogen from the soil. Moreover, the plant endophytic fungus extract ZNC stimulated the pathogen-associated molecular pattern (PAMP) triggered immunity (PTI) pathway and contributed to the ZNC-mediated defense response. Two years of field trials have shown that irrigation with ZNC at one of two optimal concentrations of 1 or 10ng/ml could significantly increase the output by 18.83% or more. The quality of potato tubers was also greatly improved, in which the contents of vitamin C, protein, and starch were significantly increased, especially the sugar content was increased by 125%. Spray application of ZNC onto potato plants significantly reduced the occurrence of potato blight disease with 66.49% of control efficacy at 200ng/ml and increased the potato yield by 66.68% or more in the field. In summary, plant endophytic fungus extract ZNC promoted potato immunity, yield, and quality and presented excellent potential in agricultural applications.

Uptake and depuration kinetics of microplastics with different polymer types and particle sizes in Japanese medaka (Oryzias latipes).

Microplastic (MP) pollution and the related impacts on aquatic species have drawn worldwide attention. However, knowledge of the kinetic profiles of MPs in fish remains fragmentary. In this study, we conducted exposure and depuration tests of the following fluorescent-labeled MPs: polyethylene (PE; sphere with 200 or 20 µm diameter) and polystyrene (PS; sphere with 20 or 2 µm diameter) using juvenile Japanese medaka (Oryzias latipes). The distribution and concentration of MPs in medaka were directly determined in-situ after tissue transparency. During the 14-day exposure, MPs was mainly detected in the gastrointestinal tract, while some MPs at the size of ≤ 20 µm were located in the area of the gills and head. The bioconcentration factor (BCF; L/kg) for MPs in medaka was estimated as 74.4 (200 µm PE), 25.7 (20 µm PE), 16.8 (20 µm PS), and 139.9 (2 µm PS). Within the first five days of depuration, MPs were exponentially eliminated from the fish body, but 2 µm PS-MPs could be still detected in the gastrointestinal tract at the end of the 10-day depuration phase. Our results suggest that MPs 2 µm in diameter may pose ecological risks to aquatic species due to their relatively higher BCF and the potential for long-term persistence in the body.

Biglycan promotes the chemotherapy resistance of colon cancer by activating NF-κB signal transduction.

Biglycan (BGN) is overexpressed in cancer stem cells of colon cancer and induces the activation of NF-κB pathway which contributes to the chemotherapy resistance of diverse cancer types. Therefore, we hypothesized that the overexpression of BGN also promoted the development of multiple drug resistance (MDR) in colon cancer via NF-κB pathway. The expression of BGN was bilaterally modulated in colon cancer cell lines HT-29 and SW-480 and the effect of treatments on the cell proliferation and resistance to 5-FU was assessed. Moreover, the role of NF-κB signaling in the BGN-mediated formation of MDR was further investigated by subjecting BGN-overexpressed SW-480 cells to the co-treatment of chemo-agents and NF-κB inhibitor, PDTC. The inhibition of BGN expression decreased the proliferation potential of HT-29 cells while the induction of BGN expression increased the potential of SW-480 cells. BGN knockdown increased HT-29 cells' sensitivity to 5-FU, represented by the lower colony number and higher apoptotic rate. To the contrary, BGN overexpression promoted the resistance of SW-480 cells to 5-FU. The effect of BGN modulation on colon cancer cells was associated with the changes in apoptosis and NF-κB pathways: BGN inhibition increased the expressions of pro-apoptosis indicators and suppressed NF-κB pathway activity while BGN overexpression had the opposite effect. It was also found that the BGN-mediated formation of MDR was impaired when NF-κB pathway was blocked. Findings outlined in the current study showed that BGN contributed to the formation of chemotherapy resistance in colon cancer cells by activating NF-κB signaling.

Nanoscale characterization of dynamic cellular viscoelasticity by atomic force microscopy with varying measurement parameters.

Cell mechanics plays an important role in regulating the physiological activities of cells. The advent of atomic force microscopy (AFM) provides a novel powerful instrument for quantifying the mechanics of single cells at the nanoscale. The applications of AFM in single-cell mechanical assays in the past decade have significantly contributed to the field of cell and molecular biology. However, current AFM-based cellular mechanical studies are commonly carried out with fixed measurement parameters, which provides limited information about the dynamic cellular mechanical behaviors in response to the variable external stimuli. In this work, we utilized AFM to investigate cellular viscoelasticity (portrayed as relaxation time) with varying measurement parameters, including ramp rate and surface dwell time, on both cell lines and primary cells. The experimental results show that the obtained cellular relaxation times are remarkably dependent on the parameter surface dwell time and ramp rate during measurements. Besides, the dependencies to the measurement parameters are variable for different types of cells, which can be potentially used to indicate cell states. The research improves our understanding of single-cell dynamic rheology and provides a novel idea for discriminating different types of cells by AFM-based cellular viscoelastic assays with varying measurement parameters.