Bioactivity and Control Efficacy of Benzovindiflupyr Against Athelia rolfsii in China.

Athelia rolfsii is a devastating soilborne pathogen that causes stem rot of peanut and severely restricts peanut production. The new generation of succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr has been registered in the United States and Brazil for managing multiple plant diseases. However, it is not registered in China to control peanut stem rot. In this study, 246 isolates from major peanut production areas in Shandong, Henan, and Hebei Provinces of China were used to determine the baseline sensitivity of A. rolfsii to benzovindiflupyr. The frequency of EC50 values of benzovindiflupyr was unimodally distributed with an average EC50 of 0.12 ± 0.05 mg/liter and a range of 0.01 to 0.57 mg/liter. Benzovindiflupyr can also strongly inhibit the germination of sclerotia, with an average EC50 of 2.38 ± 1.04 mg/liter (n = 23). In addition, benzovindiflupyr exhibited great in vivo efficacy against A. rolfsii; the protective or curative efficacy (89.87%, 20.39%) of benzovindiflupyr at a concentration of 50 mg/liter was equivalent to that of the control fungicide thifluzamide at 100 mg/liter (86.39%, 16.21%). At the same concentration (e.g., 100 mg/liter), the protective efficacy (93.99%) of benzovindiflupyr was more than twice as high as the curative efficacy (45.07%). A positive correlation existed between benzovindiflupyr and isopyrazam or mefentrifluconazole, which possibly resulted from similar chemical structures or damage to the cell membrane. Our findings provide valuable information for the application of benzovindiflupyr, and the established baseline sensitivity could facilitate the monitoring and assessment of benzovindiflupyr resistance risk.

Selection and Validation of Reference Genes for Reverse-Transcription Quantitative PCR Analysis in Sclerotium rolfsii.

Reference genes are important for the accuracy of gene expression profiles using reverse-transcription quantitative PCR (RT-qPCR). However, there are no available reference genes reported for Sclerotium rolfsii; it actually has a pretty diverse and wide host range. In this study, seven candidate reference genes (UBC, ß-TUB, 28S, 18S, PGK, EF1α and GAPDH) were validated for their expression stability in S. rolfsii under conditions of different developmental stages, populations, fungicide treatments, photoperiods and pHs. Four algorithm programs (geNorm, Normfinder, Bestkeeper and ΔCt) were used to evaluate the gene expression stability, and RefFinder was used to integrate the ranking results of four programs. Two reference genes were recommended by RefFinder for RT-qPCR normalization in S. rolfsii. The suitable reference genes were GAPDH and UBC across developmental stages, PGK and UBC across populations, GAPDH and PGK across fungicide treatments, EF1α and PGK across photoperiods, ß-TUB and EF1α across pHs and PGK and GAPDH across all samples. Four target genes (atrB, PacC, WC1 and CAT) were selected for the validation of the suitability of selected reference genes. However, using one or two reference genes in combination to normalize the expression of target genes showed no significant difference in S. rolfsii. In short, this study provided reliable reference genes for studying the expression and function of genes in S. rolfsii.

Resistance risk assessment for benzovindiflupyr in Sclerotium rolfsii and transmission of resistance genes among population.

BACKGROUND: Sclerotium rolfsii is a destructive soil-borne fungal pathogen which is distributed worldwide. In previous study, the succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr has been identified for its great antifungal activity against Sclerotium rolfsii. This study is aimed to investigate the resistance risk and mechanism of benzovindiflupyr in Sclerotium rolfsii. RESULTS: Eight stable benzovindiflupyr-resistant isolates were generated by fungicide adaptation. Although the obtained eight resistant isolates have a stronger pathogenicity than the parental sensitive isolate, they have a fitness penalty in the mycelial growth and sclerotia formation compared to the parental isolate. A positive cross-resistance existed in the resistant isolates between benzovindiflupyr and thifluzamide, carboxin, boscalid and isopyrazam. Three-point mutations, including SdhBN180D, SdhCQ68E and SdhDH103Y, were identified in the benzovindiflupyr-resistant isolates. However, molecular docking analysis indicated that only SdhDH103Y could influence the sensitivity of Sclerotium rolfsii to benzovindiflupyr. After mycelial co-incubation of resistant isolates and the sensitive isolate, resistance genes may be transmitted to the sensitive isolate. The in vivo efficacy of benzovindiflupyr and thifluzamide against benzovindiflupyr-resistant isolates was a little lower than that against the sensitive isolate but with no significant difference. CONCLUSION: The results suggested a low to medium resistance risk of Sclerotium rolfsii to benzovindiflupyr. However, once resistance occurs, it is possible to spread in the population of Sclerotium rolfsii. This study is helpful to understanding the risk and mechanism of resistance to benzovindiflupyr in multinucleate pathogens such as Sclerotium rolfsii. © 2024 Society of Chemical Industry.

Residue behavior and efficacy of benzothiazole in grains under different fumigation conditions.

BACKGROUND: Benzothiazole is a potential grain fumigant for Tribolium castaneum. However, its safety profile and suitable fumigation conditions remain unknown. We therefore investigated the insecticidal efficacy, accumulation and dissipation of benzothiazole in grains (wheat, corn and rice) under different temperatures. RESULTS: We established a universal detection method (modified QuEChERS coupled with GC-MS/MS) of benzothiazole residues in three grains, which provided high linearity (R2 > 0.999), sensitivity (limits of detection = 0.001 mg/kg, limits of quantification = 0.002-0.005 mg/kg), accuracy (recoveries = 88.18-118.75%) and precision (relative standard deviations < 4.78%). The insecticidal efficacy order of benzothiazole was 30 ≥ 10 > 20 °C and corn > wheat > rice. Temperature positively affected the accumulation/dissipation rate of benzothiazole. Rice was the most easily accumulated and dissipated grain for benzothiazole residues, while corn accumulated benzothiazole more than wheat but less than rice, with dissipation slower than wheat and rice. CONCLUSION: Our results provide important references for the application of benzothiazole and other fumigants. © 2023 Society of Chemical Industry.

Bioactivity of the DMI fungicide mefentrifluconazole against Sclerotium rolfsii, the causal agent of peanut southern blight.

BACKGROUND: Sclerotium rolfsii, the causal agent of peanut southern blight, has become increasingly prevalent and harmful in China, causing serious economic losses to the peanut industry. To effectively manage peanut southern blight, this study evaluated the bioactivity of the new-generation sterol demethylation inhibitor (DMI) fungicide mefentrifluconazole against peanut S. rolfsii. RESULTS: In this study, the DMI fungicide mefentrifluconazole exhibited excellent inhibitory activity against the mycelial growth of S. rolfsii, with a mean EC50 value of 0.21 ± 0.11 mg L-1 and a range of 0.02 to 0.55 mg L-1 for 261 isolates collected from Hebei, Henan and Shandong provinces. Mefentrifluconazole significantly reduced the biomass of mycelia and affected the morphology of hyphae. Although sclerotia were more tolerant to mefentrifluconazole than mycelial growth, mefentrifluconazole greatly inhibited the formation and germination of sclerotia. In addition, sclerotia produced by mefentrifluconazole-treated mycelia were deficient in nutrients (e.g., protein, carbohydrate and lipid). These results indicated that mefentrifluconazole may reduce the population of S. rolfsii in the following year. In greenhouse experiments, mefentrifluconazole showed control efficacy and good persistence against peanut S. rolfsii. The preventative and curative activities of mefentrifluconazole at 200 mg L-1 against southern blight still reached 95.36% and 60.94%, respectively, after 9 days of application. No correlation was observed for the sensitivity of S. rolfsii to mefentrifluconazole and the tested DMI, quinone outside inhibitor and succinate dehydrogenase inhibitor fungicides. CONCLUSION: All data indicated that mefentrifluconazole could provide favorable control efficacy against S. rolfsii from peanuts and reduce the infection and population of S. rolfsii in the following year. © 2023 Society of Chemical Industry.

Antifungal activity of Ligusticum chuanxiong essential oil and its active composition butylidenephthalide against Sclerotium rolfsii.

BACKGROUND: Peanut stem rot caused by Sclerotium rolfsii is an epidemic disastrous soil-borne disease. Recently, natural products tend to be safe alternative antifungal agents to combat pathogens. RESULTS: This work determined the preliminary antifungal activity of 29 essential oils against S. rolfsii and found that Ligusticum chuanxiong essential oil (LCEO) showed the best antifungal activity, with an EC50 value of 81.79 mg L-1 . Sixteen components (98.78%) were identified in LCEO by gas chromatography-mass spectrometry analysis, the majority by volume comprising five phthalides (93.14%). Among these five phthalides, butylidenephthalide was the most effective compound against S. rolfsii. Butylidenephthalide not only exhibited favorable in vitro antifungal activity against the mycelial growth, sclerotia production and germination of S. rolfsi, but also presented efficient in vivo efficacy in the control of peanut stem rot. Seven days after application in the glasshouse, the protective and curative efficacy of butylidenephthalide at 300 mg L-1 (52.02%, 44.88%) and LCEO at 1000 mg L-1 (49.60%, 44.29%) against S. rolfsii were similar to that of the reference fungicide polyoxin at 300 mg L-1 (54.61%, 48.28%). Butylidenephthalide also significantly decreased the oxalic acid and polygalacturonase content of S. rolfsii, suggesting a decreased infection ability on plants. Results of biochemical actions indicated that butylidenephthalide did not have any effect on the cell membrane integrity and permeability but significantly decreased nutrient contents, disrupted the mitochondrial membrane, inhibited energy metabolism and induced reactive oxygen species (ROS) accumulation of S. rolfsii. CONCLUSION: Our results could provide an important reference for understanding the application potential and mechanisms of butylidenephthalide in the control of S. rolfsii. © 2023 Society of Chemical Industry.

Combined Vacuum Evaporation and Solution Process for High-Efficiency Large-Area Perovskite Solar Cells with Exceptional Reproducibility.

Organic-inorganic hybrid perovskites exhibit outstanding performances in perovskite solar cells (PSCs). However, the complex solution chemistry of perovskites precursors renders it difficult to prepare large-area devices in a reproducible way, which is a prerequisite for the technology to make an impact beyond lab scale. Vacuum processing, instead, is an established technology for large-scale coating of thin films. However, with respect to the hybrid perovskites it is highly challenging due to the high vapor pressure of the organic ammonium halide. In this work, vacuum evaporation of lead iodide and solution processing of organic ammonium halide is combined to produce large-area homogeneous perovskite films with large grains in a highly reproducible way. The resulting PSCs achieve a power conversion efficiency (PCE) of 24.3% (certified 23.9%) on small area (0.10 cm2 ), 24.0% (certified 23.7%) on large area (1 cm2 ) and 20.0% for minimodule (16 cm2 ), and maintain 90% of its initial efficiency after 1000 h 1-sun operation. The vacuum evaporation prevents advert environmental effects on lead halide formation and guarantees a reproducible fabrication of high-quality large-area perovskite films, which opens a promising way for large-scale fabrication of perovskite optoelectronics.

Double Layer Composite Electrode Strategy for Efficient Perovskite Solar Cells with Excellent Reverse-Bias Stability.

Perovskite solar cells (PSCs) have become the representatives of next generation of photovoltaics; nevertheless, their stability is insufficient for large scale deployment, particularly the reverse bias stability. Here, we propose a transparent conducting oxide (TCO) and low-cost metal composite electrode to improve the stability of PSCs without sacrificing the efficiency. The TCO can block ion migrations and chemical reactions between the metal and perovskite, while the metal greatly enhances the conductivity of the composite electrode. As a result, composite electrode-PSCs achieved a power conversion efficiency (PCE) of 23.7% (certified 23.2%) and exhibited excellent stability, maintaining 95% of the initial PCE when applying a reverse bias of 4.0 V for 60 s and over 92% of the initial PCE after 1000 h continuous light soaking. This composite electrode strategy can be extended to different combinations of TCOs and metals. It opens a new avenue for improving the stability of PSCs.

Multifunctional succinate additive for flexible perovskite solar cells with more than 23% power-conversion efficiency.

Flexible perovskite solar cells (FPSCs) have emerged as power sources in versatile applications owing to their high-efficiency characteristics, excellent flexibility, and relatively low cost. Nevertheless, undesired strain in perovskite films greatly impacts the power-conversion efficiency (PCE) and stability of PSCs, particularly in FPSCs. Herein, a novel multifunctional organic salt, methylammonium succinate, which can alleviate strain and reinforce grain boundaries, was incorporated into the perovskite film, leading to relaxed microstrain and a lower defect concentration. As a result, a PCE of 25.4% for rigid PSCs and a record PCE of 23.6% (certified 22.5%) for FPSCs have been achieved. In addition, the corresponding FPSCs exhibited excellent bending durability, maintaining ∼85% of their initial efficiency after bending at a 6 mm radius for 10 000 cycles.

Sequential vacuum-evaporated perovskite solar cells with more than 24% efficiency.

Vacuum evaporation is promising for the high-throughput fabrication of perovskite solar cells (PSCs) because of its solvent-free characteristic, precise control of film thickness, and compatibility with large-scale production. Nevertheless, the power conversion efficiency (PCE) of PSCs fabricated by vacuum evaporation lags behind that of solution-processed PSCs. Here, we report a Cl-containing alloy-mediated sequential vacuum evaporation approach to fabricate perovskite films. The presence of Cl in the alloy facilitates organic ammonium halide diffusion and the subsequent perovskite conversion reaction, leading to homogeneous pinhole-free perovskite films with few defects. The resulting PSCs yield a PCE of 24.42%, 23.44% (certified 22.6%), and 19.87% for 0.1, 1.0, and 14.4 square centimeters (mini-module, aperture area), respectively. The unencapsulated PSCs show good stability with negligible decline in performance after storage in dry air for more than 4000 hours. Our method provides a reproducible approach for scalable fabrication of large-area, high-efficiency PSCs and other perovskite-based optoelectronics.