TOPK Inhibition Enhances the Sensitivity of Colorectal Cancer Cells to Radiotherapy by Reducing the DNA Damage Response.

OBJECTIVE: Abnormal expression of T-lymphokine-activated killer cell-originated protein kinase (TOPK) was reported to be closely related to the resistance of prostate cancer to radiotherapy and to targeted drug resistance in lung cancer. However, the role of TOPK inhibition in enhancing radiosensitivity of colorectal cancer (CRC) cells is unclear. This study aimed to evaluate the radiosensitization of TOPK knockdown in CRC cells. METHODS: The expression of TOPK was detected in CRC tissues by immunohistochemistry, and the effect of TOPK knockdown was detected in CRC cells by Western blotting. CCK-8 and clonogenic assays were used to detect the growth and clonogenic ability of CRC cells after TOPK knockdown combined with radiotherapy in CRC cells. Furthermore, proteomic analysis showed that the phosphorylation of TOPK downstream proteins changed after radiotherapy. DNA damage was detected by the comet assay. Changes in the DNA damage response signaling pathway were analyzed by Western blotting, and apoptosis was detected by flow cytometry. RESULTS: The expression of TOPK was significantly greater in CRC tissues at grades 2-4 than in those at grade 1. After irradiation, CRC cells with genetically silenced TOPK had shorter comet tails and reduced expression levels of DNA damage response-associated proteins, including phospho-cyclin-dependent kinase 1 (p-CDK1), phospho-ataxia telangiectasia-mutated (p-ATM), poly ADP-ribose polymerase (PARP), and meiotic recombination 11 homolog 1 (MRE11). CONCLUSIONS: TOPK was overexpressed in patients with moderately to poorly differentiated CRC. Moreover, TOPK knockdown significantly enhanced the radiosensitivity of CRC cells by reducing the DNA damage response.

Aza[5]helicene-Derived Semiconducting Polymers for Improved Performance in Perovskite Solar Cells: Exploring Energetic and Morphological Influences.

The strategic design of solution-processable semiconducting polymers possessing both matched energy levels and elevated glass transition temperatures is of urgent importance in the progression of thermally robust n-i-p perovskite solar cells with efficiencies exceeding 25 %. In this work, we employed direct arylation polymerization to achieve the high-yield synthesis of three aza[5]helicene-derived copolymers with distinct HOMO energy levels and exceptional glass transition temperatures. Upon integration of these semiconducting polymers into formamidinium lead triiodide-based perovskite solar cells, marked disparities in photovoltaic parameters manifest, primarily stemming from variations in the electrical conductivity and film morphology of the hole transport layers. The p-A5HP-E-POZOD-E copolymer, featuring a main chain comprising alternating repeats of aza[5]helicene, ethylenedioxythiophene, phenoxazine, and ethylenedioxythiophene, attains an initial average efficiency of 25.5 %, markedly surpassing reference materials such as spiro-OMeTAD (23.0 %), PTAA (17.0 %), and P3HT (11.6 %). Notably, p-A5HP-E-POZOD-E exhibits a high cohesive energy density, resulting in enhanced Young's modulus and diminished external species diffusion coefficients, thereby conferring perovskite solar cells with exceptional 85 °C tolerance and operational stability.

Molecular engineering of nitrogen-rich helicene based organic semiconductors for stable perovskite solar cells.

Polycyclic heteroaromatics play a pivotal role in advancing the field of high-performance organic semiconductors. In this study, we report the synthesis of a pyrrole-bridged double azahelicene through intramolecular oxidative cyclization. By incorporating bis(4-methoxyphenyl)amine (OMeDPA) and ethylenedioxythiophene-phenyl-OMeDPA (EP-OMeDPA) into the sp3-nitrogen rich double helicene framework, we have successfully constructed two organic semiconductors with ionization potentials suitable for application in perovskite solar cells. The amorphous films of both organic semiconductors exhibit hole density-dependent mobility and conductivity. Notably, the organic semiconductor utilizing EP-OMeDPA as the electron donor demonstrates superior hole mobility at a given hole density, which is attributed to reduced reorganization energy and increased centroid distance. Moreover, this organic semiconductor exhibits a remarkably elevated glass transition temperature of up to 230 °C and lower diffusivity for external small molecules and ions. When employed as the p-doped hole transport layer in perovskite solar cells, TMDAP-EP-OMeDPA achieves an improved average efficiency of 21.7%. Importantly, the solar cell with TMDAP-EP-OMeDPA also demonstrates enhanced long-term operational stability and storage stability at 85 °C. These findings provide valuable insights into the development of high-performance organic semiconductors, contributing to the practical application of perovskite solar cells.

[Genetic diversity analysis and fingerprints of Chrysanthemum×morifolium based on SSR molecular markers].

The present study aims to explore the genetic diversity of germplasm resources of Chrysanthemum×morifolium (hereinafter, C.×morifolium) at the molecular level and to establish a fingerprint database of C.×morifolium varieties. We employed 12 pairs of primers with high levels of polymorphism, clear bands, and high degrees of reproducibility to analyze the SSR molecular markers and genetic diversity of 91 C.×morifolium materials and 14 chrysanthemum- related materials. With regard to constructing the fingerprints of the tested materials, we chose 9 pairs of core primers. The findings revealed that 12 primer pairs detected 104 alleles in 105 samples, ranging from 2 to 26. The average number of observed alleles (Na) per site was 9.25. The average number of effective alleles (Ne) per site was 2.745 6, with its range being 1.276 0 to 4.742 5. Shannon genetic diversity index (I) values ranged between 0.513 3 and 2.239 9 (M=1.209 0). Nei's gene diversity index (H) ranged between 0.216 3 and 0.789 1 (M=0.578 0). The observed heterozygosity (Ho) ranged between 0.223 3 and 0.895 2 (M=0.557 5). The expected heterozygosity (He) ranged between 0.217 4 and 0.793 3 (M=0.580 8). The polymorphism information content (PIC) ranged between 0.211 5 and 0.774 0 (M=0.532 9). The genetic similarity (GS) ranged between 0.228 5 and 1.000 0 (M=0.608 3). Cluster analysis revealed that when the genetic distance (GD) equals to 0.30, the tested materials can be classified into 2 groups. When the GD equals to 0.27, the first group can be divided into 6 subgroups; accordingly, 105 tested materials can be divided into 7 subgroups. The cophenetic correlation test was carried out based on the cluster analysis, and the corresponding results showed that the cluster map correlated with the genetic similarity coefficient (r=0.952 73). According to the results of Structure population analysis, we obtained the optimal population number, with the true number of populations (K) being 3 and the population being divided concerning Q≥0.5. Three subgroups, i.e., Q1, Q2 and Q3, included 34, 33 and 28 germplasms, respectively, and the remaining 10 germplasms were identified as the mixed population. During the experiment, 9 pairs of core primers were screened among the total of 12 for a complete differentiation regarding 105 tested materials, and the fingerprints of 91 C.×morifolium materials and 14 chrysanthemum-related materials were further constructed. Overall, there were significant genetic differences and rich genetic diversity among C.×morifolium materials, which would shed light on the garden application and variety selection fields of C.×morifolium. The fingerprint database of 105 C.×morifolium varieties and chrysanthemum-related species may provide technical support for future research regarding the identification and screening system of C.×morifolium varieties.

Surfactants Improving the Wetting Behavior and Adhesion Mechanism of Pesticide Dilution Droplets on Jujube Leaf Surfaces.

Fruit tree leaves have different chemical compositions and diverse wax layer structures that result in different patterns of wetting and pesticide solution spreading on their surface. Fruit development is a time when pests and diseases occur, during which a large number of pesticides are needed. The wetting and diffusion properties of pesticide droplets on fruit tree leaves were relatively poor. To solve this problem, the wetting characteristics of leaf surfaces with different surfactants were studied. The contact angle, surface tension, adhesive tension, adhesion work, and solid-liquid interfacial tension of five surfactant solution droplets on jujube leaf surfaces during fruit growth were studied by the sessile drop method. C12E5 and Triton X-100 have the best wetting effects. Two surfactants were added to a 3% beta-cyfluthrin emulsion in water, and field efficacy tests were carried out on peach fruit moths in a jujube orchard at different dilutions. The control effect is as high as 90%. During the initial stage when the concentration is low, due to the surface roughness of the leaves, the surfactant molecules adsorbed at the gas-liquid and solid-liquid interfaces reach an equilibrium, and the contact angle on the leaf surface changes slightly. With increasing surfactant concentration, the pinning effect in the spatial structure on the leaf surface is overcome by liquid droplets, thereby significantly decreasing the contact angle. When the concentration is further increased, the surfactant molecules form a saturated adsorption layer on the leaf surface. Due to the existence of a precursor water film in the droplets, surfactant molecules on the interface continuously move to the water film on the surface of jujube tree leaves, thus causing interactions between the droplets and the leaves. The conclusion of this study provides theoretical guidance for the wettability and adhesion of pesticides on jujube leaves, so as to achieve the purpose of reducing pesticide use and improving pesticide efficacy.

Arabidopsis COPT1 copper transporter uses a single histidine to regulate transport activity and protein stability.

Copper acquisition and subsequent delivery to target proteins are essential for many biological processes. However, the cellular levels of this trace element must be controlled because of its potential toxicity. The COPT1 protein rich in potential metal-binding amino acids functions in high affinity copper uptake at the plasma membrane of Arabidopsis cells. The functional role of these putative metal-binding residues is largely unknown. Through truncations and site-directed mutagenesis, we identified His43, a single residue within the extracellular N-terminal domain as absolutely critical for copper uptake of COPT1. Substitution of this residue with leucine, methionine or cysteine almost inactivated transport function of COPT1, implying that His43 fails to serves as a copper ligand in the regulation of COPT1 activity. Deletion of all extracellular N-terminal metal-binding residues completely blocked copper-stimulated degradation but did not alter the subcellular distribution and multimerization of COPT1. Although mutation of His43 to alanine and serine retained the transporter activity in yeast cells, the mutant protein was unstable and degraded in the proteasome in Arabidopsis cells. Our results demonstrate a pivotal role for the extracellular residue His43 in high affinity copper transport activity, and suggest common molecular mechanisms for regulating both metal transport and protein stability of COPT1.

MARK3 kinase: Regulation and physiologic roles.

Microtubule affinity-regulating kinase 3 (MARK3), a member of the MARK family, regulates several essential pathways, including the cell cycle, ciliated cell differentiation, and osteoclast differentiation. It is important to understand the control of their activities as MARK3 contains an N-terminal serine/threonine kinase domain, ubiquitin-associated domain, and C-terminal kinase-associated domain, which perform multiple regulatory functions. These functions include post-translational modification (e.g., phosphorylation) and interaction with scaffolding and other proteins. Differences in the amino acid sequence and domain position result in different three-dimensional protein structures and affect the function of MARK3, which distinguish it from the other MARK family members. Recent data indicate a potential role of MARK3 in several pathological conditions, including congenital blepharophimosis syndrome, osteoporosis, and tumorigenesis. The present review focuses on the physiological and pathological role of MARK3, its regulation, and recent developments in the small molecule inhibitors of the MARK3 signalling cascade.

Inhibiting ALK-TOPK signaling pathway promotes cell apoptosis of ALK-positive NSCLC.

T-LAK cell-oriented protein kinase (TOPK) is a potential therapeutic target in tumors. However, its role in anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) has not been reported. Here, we found that TOPK was highly expressed in ALK-positive NSCLC. Additionally, ALK was identified as another upstream kinase of TOPK by in vitro kinase assay screening. Then, it was proven that ALK phosphorylated TOPK at Y74 in vitro and ex vivo, and the pathways downstream of ALK-TOPK were explored by phosphoproteomic analysis. Subsequently, we demonstrated that inhibiting TOPK enhanced tumor sensitivity to alectinib (an ALK inhibitor). The combination of alectinib and HI-032 (a TOPK inhibitor) suppressed the growth and promoted the apoptosis of ALK-positive NSCLC cells ex vivo and in vivo. Our findings reveal a novel ALK-TOPK signaling pathway in ALK-positive NSCLC. The combination of alectinib and HI-032 might be a promising therapeutic strategy for improving the sensitivity of ALK-positive NSCLC to targeted therapy.

Regulating the Entire Journey of Pesticide Application on Surfaces of Hydrophobic Leaves Modified by Pathogens at Different Growth Stages.

Under the background of the strategy of reducing pesticide application and increasing efficiency, the mechanism and common technology of efficient and accurate target deposition of chemical pesticides are the key development direction. The interaction between pesticide droplets and a leaf surface affects the deposition behavior of pesticides. However, cucumber leaf surface modified by powdery mildew pathogens at different growth stages is more hydrophobic than a normal leaf surface, which hinders the accurate deposition of pesticides on cucumber powdery mildew leaves. Here, an effective strategy for controlling pesticide efficiency for the entire journey of pesticide application is proposed. Based on the impact dynamics of droplets, the dynamic direction of droplet bounce is determined, the trajectory of droplet rebound is preliminarily determined, and the pinning sites formed by droplets on the surface of cucumber leaves with powdery mildew are confirmed. By analyzing the dynamics in the retraction stage and the energy dissipation rate for droplets after impact, the basic parameters that can be used to simply characterize droplet rebound are screened out, and the effect of addition of an effective surfactant is determined by characterizing the basic parameters (energy dissipation rate, retraction rate, recovery coefficient). The molecular structure formed by the addition of nonionic surfactant in pesticide solution is more appropriate to the interaction between the powdery mildew layer and the pesticide solution, which ensured that the droplets are well wet and deposited on cucumber powdery mildew leaves. Meanwhile, a force balance model for the pesticide droplet wetting state is established to calculate the pinning force for the droplet and predict the transition direction for the droplet wetting state. Impact dynamics combined with force balance model analysis provides a constructive method to improve pesticide utilization during the entire journey for pesticide application on hydrophobic plant surfaces.

Chrysene-Based Azahelicene π-Linker of D-π-D-Type Hole-Transporting Materials for Perovskite Solar Cells.

Chrysene is a readily available material for exploring new polycyclic aromatic hydrocarbons (PAHs). In this study, two chrysene based azahelicenes, nine-membered BA7 and ten-membered DA6, are constructed by intermolecular oxidative annulation of 6-aminochrysene and intramolecular annulation of N6 ,N12 -bis(1-chloronaphthalen-2-yl)chrysene-6,12-diamine, respectively. The hexylated BA7 and DA6 and their brominated products were undoubtedly characterized by single crystal XRD. Subsequent amination with bis(9-methyl-9H-carbazol-3-yl)amine (BMCA) electron donor afforded D-π-D-type semiconductors BA7-BMCA and DA6-BMCA with beneficial properties to act as hole transport materials for perovskite solar cell. Compared with 19.4 % champion power conversion efficiency (PCE) of BA7-BMCA based device, a higher PCE of 20.2 % for DA6-BMCA counterpart may be attributed to its S-shaped double helicene-like linker with extended π-conjugated system.

Regulating Droplet Wetting and Pinning Behaviors on Pathogen-Modified Hydrophobic Surfaces: Strategies and Working Mechanisms.

Hydrophobic surfaces modified by pathogens in agricultural production are one of the main reasons to reduce the utilization of pesticides. Adding surfactants to pesticide solutions is a common method to improve their wetting and spreading properties. In this work, the interaction mechanism between pathogen-modified hydrophobic surfaces and mixtures of surfactants and a pesticide was studied in detail. The interaction mechanism was determined by characterizing the wetting and spreading behaviors of droplets on cucumber powdery mildew leaves at different growth stages. When surfactants were added, droplets on cucumber powdery mildew leaves were in the Wenzel wetting state, the pinning force weakened, the contact line speed accelerated, and the adhesion force increased. We explained the micellar state and aggregation behavior of surfactant molecules in a pesticide solution that was applied to the surface of cucumber powdery mildew leaves. Droplets of solutions containing nonionic surfactants easily formed semibald micelles, binding to the pathogen of powdery mildew, whereas droplets containing cationic surfactants did not do so. Because of the electrostatic interaction between cationic surfactant molecules and powdery mildew pathogens, cationic surfactant molecules did not wet the pathogens very well, so we suggest adding nonionic surfactants rather than cationic surfactants to improve the wetting and spreading of pesticide solutions on cucumber powdery mildew leaves. This study provides new insights into enhancing the wetting and deposition of droplets on pathogen-modified hydrophobic surfaces.

Optimization Strategy to Inhibit Droplets Rebound on Pathogen-Modified Hydrophobic Surfaces.

The deposition and retention of pesticide sprays on the surface of hydrophobic plant leaves is a major agricultural challenge, and the deposition of hydrophobic surfaces caused by plant leaf diseases is also a major agricultural problem. Many recent studies have focused on evaluating the effect of adding surfactants to water rather than to pesticide solutions to increase the deposition and retention of spray liquids. Here, we report a strategy to solve the problem of deposition and retention by studying the impact of the behavior of pesticide droplets with added surfactants and performing kinetic analysis on cucumber leaves with powdery mildew. The reduction in the bounce and splash of the pesticide droplets was analyzed by combining the pinning site formed in the retraction stage and the viscous dissipation in the rebound stage. In the practical application of the pesticide spray, we can clearly see that the bounce, splash, and powdery mildew spore ejection decreased when surfactants were added to the pesticide spray that was used on the cucumber leaves, and the adhesion and retention increased. The proposed comprehensive method is helpful for understanding the interactions between pesticide spray droplets and the surface of cucumber leaves with powdery mildew.

Tank-mixing adjuvants enhanced the efficacy of fludioxonil on cucumber anthracnose by ameliorating the penetration ability of active ingredients on target interface.

In this study, pot and field experiments showed that S903, Hasten and Gemini-31511 can significantly enhanced the control efficacy of fludioxonil on cucumber anthracnose. Then by studying the deposition and penetration interaction between active ingredients and cucumber leaves to revealed how the adjuvants influence the interaction process between pesticide active ingredients and target plants to improve the control efficacy. By analysis the effect of fludioxonil deposition to synergism of adjuvants, indicated that fludioxonil active ingredient deposition caused by adjuvants was not the main factor for the adjuvants synergistic effect. Fludioxonil + S903 yielded the lowest surface tension and contact angle, which also implying the best wetting ability. The mean diameters in Hasten + fludioxonil group were much smaller than those in only fludioxonil group (5.39 µm-90 g a.i. ha-1, 5.50 µm-180 g a.i. ha-1), the average particle size only had 3.45 µm (90 g a.i. ha-1) and 3.94 µm (180 g a.i. ha-1). And the result of spray droplets was consistent with the particles of fludioxonil crystals observed on glass slides and cucumber leaves. Therefore, S903 improved the penetrability of fludioxonil in the target plants by improving the wetting and dispersion of active ingredients on the target interface. Meantime, Hasten improved the penetrability of fludioxonil in the target plants by decreasing the particle size of active ingredients.

Performance matching between the surface structure of cucumber powdery mildew in different growth stages and the properties of surfactant solution.

BACKGROUND: Understanding performance matching of pesticide droplets on the surface of cucumber leaves modified by powdery mildew is of practical importance for the agricultural sector. Here, the surface texture and wettability of cucumber leaves covered by powdery mildew were systematically examined using parameters such as micromorphology, physicochemical properties, and liquid droplet contact angle measurements. RESULTS: Our results show that powdery mildew growth can be divided into four distinct stages according to the surface texture characteristics of the diseased cucumber leaves. The three-dimensional (3D) surface structures of powdery mildew layers on cucumber leaves had individual characteristics at different mildew growth stages, among which powdery mildew was more easily spread in the last growth stage, and powdery mildew height was greatest in the NO. 2 growth stage (Sa  = 425.35 µm). Surface free energy values, static contact angle, and contact angle hysteresis all correlated strongly with the surface characteristics of powdery mildew layers at different growth stages. When the concentration of surfactant reached the critical micelle concentration, the wetting state of AEO-5 solution droplets on the surface of cucumber powdery mildew leaves reached the Wenzel state more easily. The wettability of a droplet on the leaf surface depends on the state of the monomer and micelle in the surfactant solution and the surface characteristics of the powdery mildew-covered leaf. CONCLUSION: The 3D structure and relative dielectric constant of powdery mildew-covered leaves influenced surface texture characteristics, which in turn controlled the wetting and matching ability of surfactant droplets on diseased leaves. This work provides valuable new insights into the matching of the structure of powdery mildew-covered plant leaves with the properties of surfactant solutions. © 2021 Society of Chemical Industry.

Ubiquitin-independent proteasome system is required for degradation of Arabidopsis COPPER TRANSPORTER 2.

Plants have evolved sophisticated mechanisms to adjust to deficiency or excess of nutrients. Membrane transport proteins play a central role in nutrient uptake from soil. In Arabidopsis thaliana, the COPPER TRANSPORTOR (COPT) family encodes high-affinity copper transporters. COPT2 is transcriptionally regulated in response to changing levels of cellular copper. However, little is known about whether COPT2 activity is subject to multiple levels of regulation. Here, we showed that the plasma membrane-/endoplasmic reticulum-resident COPT2 protein is degraded in response to excess copper. Confocal microscopy analysis together with pharmacological treatment with a vesicle trafficking inhibitor or vacuolar ATPase inhibitor indicated that copper-mediated downregulation of COPT2 is unlikely to be controlled by endosomal recycling and vacuolar system. However, COPT2 protein is stabilized by proteasome inhibition. Through site-directed mutagenesis, we found that COPT2 cannot be ubiquitinated, and lysine residues at the C-terminus is dispensable for copper-induced degradation of COPT2 but required for copper acquisition. Altogether, our findings reveal that unlike many metal transporters in Arabidopsis, COPT2 is a substrate of ubiquitin-independent proteasomal degradation but not of vacuolar proteases. These findings highlight the mechanistic diversity and complexity of plasma membrane transporter degradation.

Dissipation kinetics and safety evaluation of pyraclostrobin and its desmethoxy metabolite BF 500-3 in a cucumber greenhouse agroecosystem.

Pyraclostrobin (PYR), a fungicide of the strobilurin class, is used to control many different kinds of fungal diseases in greenhouses and on agricultural fields. In the present study, an efficient method was established for simultaneously determining PYR and its metabolite BF 500-3 in cucumber fruits, leaves, and soil matrices using QuEChERS pretreatment coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The residue levels and dissipation kinetics of PYR were determined under greenhouse conditions. The recoveries ranged from 89.8 to 103.6% with relative standard deviations (RSDs) of 3.6-7.5% at three spiking levels. The results demonstrated that PYR dissipated quickly in the cucumber field with half-lives (DT50) of 2.14-4.17 days on different sites and in different matrices. The residue of its metabolite BF 500-3 was very low and showed a trend of first increasing and then decreasing. The degradation rate of PYR in soil was the fastest, followed by that on cucumber fruits and leaves. The terminal residue of PYR at an application rate of 150 g a.i. ha-1 (the maximum recommended rate) in cucumber fruits was below the maximum residue limit (MRL) of 0.5 mg/kg established in China. However, the application of the fungicide at 225 g a.i. ha-1 (1.5× the maximum recommended rate) resulted in residues that were above the MRL 1 day after the final application, which is an unacceptable risk. Therefore, the application dosage of PYR at the recommended rates was safe to human beings and animals.

Impact of the equilibrium relationship between deposition and wettability behavior on the high-efficiency utilization of pesticides.

BACKGROUND: Often, due to the occurrence of powdery mildew, cucumber leaf surfaces is changed into a more hydrophobic surface, which affects wetting and spreading of liquid pesticides, reducing their efficiency. The wetting and deposition behavior of liquid pesticides can be improved by adding surfactants to pesticides. Added surfactants affect the spray volume of the pesticide, which can lead to waste and a low utilization rate of the pesticide. It is important to further balance the relationship between deposition and wettability of pesticide liquid on the surfaces of healthy leaves and powdery mildew leaves of cucumber. RESULTS: This study evaluated the deposition and wettability of hexaconazole (Hexa) with surfactants on the surfaces of healthy leaves and powdery mildew leaves of cucumber. The deposition rates of Hexa with surfactants were lower than that of Hexa due to the loss of solution in conventional spray volume (750 L ha-1 ). The deposition rate of Hexa did not necessarily increase with increasing spray volume, and the deposition rate did not increase again after the spray volume increased to a certain level. Under the condition that the prevention and control effect were not reduced, we found that the volume of solution spray with added Silwet618 or AEO-5 should be adjusted to half of the normal volume, while the volume of solution spray with added 1227 or rosin-based quarternary ammonium should be adjusted to two-thirds of the normal volume to increase the deposition rate by approximately 30%. Regarding the wetting parameters, the results showed that the wettability of Hexa with Silwet618 was the best, but their combination was not ideal according to the composite index and deposition. By analyzing all the parameters, it was found that the spray volume reduction of Hexa with surfactant was approximately equal to the solution surface tension reduction, compared with the parameters of Hexa. CONCLUSION: The equilibrium relationship between deposition rate and wetting parameters was determined to provide guidance for the application of surfactants and to lower the dosage of pesticides to increase their efficiency and reduce their application. © 2021 Society of Chemical Industry.

Activity of the Novel Fungicide Mefentrifluconazole Against Colletotrichum scovillei.

The prevalence and destructiveness of anthracnose, caused by Colletotrichum scovillei, in pepper production regions seriously affects pepper yield and quality. Mefentrifluconazole, the first of the isopropanol-azole subgroup of triazole fungicides, was introduced for the control of pepper anthracnose. However, the growth characteristics of pepper fruit and rapid spread of anthracnose suggest that the fungicide application method must be optimized to enhance fungicide efficacy. The sensitivity of C. scovillei to mefentrifluconazole was determined by mycelial growth and germ tube elongation assays using 157 single-spore isolates with mean 50% effective concentration values of 0.462 ± 0.138 and 0.359 ± 0.263 mg/liter, respectively. The in vivo data also showed that mefentrifluconazole had favorable protective and curative effects against pepper anthracnose. Mefentrifluconazole significantly affected C. scovillei infection on pepper by reducing appressorium formation and sporulation, shriveling spores and germ tubes, and causing the abnormal development of appressoria and conidiophores. Mefentrifluconazole could move acropetally, horizontally, and basipetally in pepper plants. Compared with a knapsack sprayer, mefentrifluconazole applied by mist sprayer exhibited significantly better activity against pepper anthracnose. Additionally, as the spray volume increased from 45 to 150 liters/ha, the control efficacy of mefentrifluconazole first increased and then tended to be steady, with an optimal spray volume of 90 liters/ha. The difference in disease control efficacy was related to the deposition and droplet distribution of mefentrifluconazole on the pepper fruit. These results provide scientific guidance for the application of mefentrifluconazole in pepper fields and improved fungicide utilization.

The relationship between features enabling SDHI fungicide binding to the Sc-Sdh complex and its inhibitory activity against Sclerotinia sclerotiorum.

BACKGROUND: A new generation of succinate dehydrogenase inhibitors (SDHIs) with high efficiency and broad-spectrum antifungal activity has been frequently used in crop production. Sclerotinia stem rot is a major disease of various plants and crops caused by Sclerotinia sclerotiorum. Although benzovindiflupyr and isopyrazam reportedly have high activity against S. sclerotiorum, little is known about the bioactivity of different SDHIs classes against S. sclerotiorum or the mechanism of their differential antifungal activity. RESULTS: The in vitro tests revealed that the pyrazole-4-carboxamides of SDHIs (benzovindiflupyr, isopyrazam, fluxapyroxad, pydiflumetofen) had the highest activity against S. sclerotiorum followed by pyridine carboxamides (boscalid), pyridinyl-ethyl benzamides (fluopyram) and thiazole carboxamides (thifluzamide), and of these thifluzamide showed poor antifungal activity with EC50 values greater than 6.01 mg L-1 . The pyrazole-4-carboxamides of SDHIs showed satisfactory protective and curative activity against Sclerotinia stem rot. After treatment with the pyrazole-4-carboxamides of SDHIs, mitochondrial function in S. sclerotiorum decreased significantly. The enzyme activity assays revealed a lower affinity between thifluzamide and the Sc-Sdh complex than was observed for the other six fungicides, with IC50 values ranging from 0.0036 to 1.2088 µmol L-1 . Additionally, the docking positions of fungicides were similar, yet binding energies were different in the docking study with the Sdh complex. The correspondingly weaker hydrogen bonds may be responsible for the poor activity of thifluzamide against S. sclerotiorum. CONCLUSION: Understanding different binding features of various SDHIs classes with the Sc-Sdh complex might be beneficial for the design and development of highly effective broad-spectrum fungicides to ensure high yield and quality in crops by reducing fungicide use. © 2020 Society of Chemical Industry.

Fungicide Formulations Influence Their Control Efficacy by Mediating Physicochemical Properties of Spray Dilutions and Their Interaction with Target Leaves.

In this study, three types of pyraclostrobin formulations (including emulsifiable concentrate (EC), suspension concentrate (SC), and microcapsules (MCs)) were used to control cucumber anthracnose. Pyraclostrobin EC had the highest inhibitory activity against Colletotrichum orbiculare in vitro. Much different from the bioactivity in vitro, pyraclostrobin MCs exhibited the highest control efficacy on cucumber anthracnose both in pot and field experiments. The physicochemical properties (particle size, surface tension) of the spray dilution, their interaction with target leaves (contact angle, adhesional tension, work of adhesion, retention, crystallization) and dissipation dynamic of the active ingredient were found to be highly potential factors that would significantly influence the control efficacy of pesticide formulations. Results showed that the control efficacies of different formulations of pyraclostrobin were determined mainly by the final behavior of the pesticides at the target interface, namely, the retention, crystallization, and dissipation dynamics of active ingredients. This study had revealed crucial factors that would influence the efficacy of different formulations of pyraclostrobin and thus could guide the rational and efficient use of different formulations of pesticides on target crops.