Ionotropic γ-aminobutyric acid (GABA) receptors in insects, specifically those composed of the RDL (resistant to dieldrin) subunit, serve as important targets for commonly used synthetic insecticides. These insecticides belong to various chemical classes, such as phenylpyrazoles, cyclodienes, meta-diamides, and isoxazolines, with the latter two potentially binding to the transmembrane inter-subunit pocket. However, the specific amino acid residues that contribute to the high sensitivity of insect RDL receptors to these novel insecticides remain elusive. In this study, we investigated the susceptibility of seven distinct Drosophila melanogaster Rdl point mutants against four meta-diamide and isoxazoline insecticides: isocycloseram, fluxametamide, fluralaner, and broflanilide. Our findings indicate that, despite exhibiting increased sensitivity to fluralaner in vitro, the Rdl^I276C mutant showed resistance to isocycloseram and fluxametamide. Similarly, the double-points mutant Rdl^I276F+G279S also showed decreased sensitivity to the tested isoxazolines. On the other hand, the Rdl^G335M mutant displayed high levels of resistance to all tested insecticides. Molecular modeling and docking simulations further supported these findings, highlighting similar binding poses for these insecticides. In summary, our research provides robust in vivo evidence supporting the idea that the inter-subunit amino acids within transmembrane M1 and M3 domains form the binding site crucial for meta-diamide and isoxazoline insecticide interactions. This study highlights the complex interplay between mutations and insecticide susceptibility, paving the way for more targeted pest control strategies.

Camellia oleifera, a woody oilseed plant native to China, is highly susceptible to anthracnose, a fungal disease that poses a significant threat to its yield and quality. Mitophagy, a specialized form of autophagy that specifically targets dysfunctional mitochondria, is crucial for cellular homeostasis, stress response, and pathogenesis in fungi. The proteins that potentially participate in mitophagy in Colletotrichum camelliae were identified herein using immunoprecipitation-mass spectrometry (IP-MS) by screening for the potential protein interactors of the core autophagy-related protein, CaAtg8. Among the identified mitochondria-associated proteins, CaSun1 was selected for further investigation. Phenotypic analyses revealed that CaSun1 is a critical regulator of vegetative growth, conidiation, and pathogenicity. CaSun1 localized to the mitochondria, consistent with the conserved function of SUN family proteins. Notably, the findings revealed that CaSun1 was essential for mitophagy and colocalized with CaAtg8 during nitrogen starvation. Functional analyses demonstrated that CaSun1-mediated mitophagy is vital for the growth of invasive hyphae and pathogenicity in C. camelliae. In summary, our findings indicated that CaSun1 mediates mitophagy by facilitating the recruitment of CaAtg8 in C. camelliae, thereby contributing to the establishment of anthracnose. This study provided novel insights into the molecular mechanisms underlying the pathogenesis of fungal infections and identified a potential target for disease control.

Soybean (Glycine max L.) holds significant global importance and is extensively cultivated in Heilongjiang Province, China. Soybean can be infected by Fusarium species, causing root rot, seed decay, stem rot, and leaf blight. In 2021 to 2022, a field survey of soybean diseases was carried out in 11 regions of Heilongjiang Province, and 186 soybean leaves with leaf blight symptoms and 123 soybean roots with root rot symptoms were collected. Unexpectedly, a considerable number of Fusarium isolates were obtained not only from root samples but also from leaf samples. A total of 584 Fusarium isolates (416 from leaves and 168 from roots) were obtained and identified as 18 Fusarium species based on morphological features and multilocus phylogenetic analyses with tef1 and rpb2 sequences. Fusarium graminearum and Fusarium sp. 1 in FOSC were the dominant species within soybean leaf and root samples, respectively. Pathogenicity tests were conducted for all Fusarium isolates on both soybean leaves and roots. Results showed that F. graminearum, F. ipomoeae, F. citri, F. compactum, F. flagelliforme, F. acuminatum, and F. sporotrichioides were pathogenic to both soybean leaves and roots. F. solani, F. avenaceum, F. pentaseptatum, F. serpentinum, F. annulatum, and Fusarium sp. 1 in FOSC were pathogenic to soybean roots, not to leaves. To our knowledge, this is the first study to thoroughly investigate soybean-associated Fusarium populations in leaves and roots in Heilongjiang Province.

Phytophthora cinnamomi causes significant root rot in hickory, leading to substantial yield losses. While Bacillus spp. are recognized as beneficial rhizosphere microorganisms, their application against hickory root rot and their impact on rhizosphere microbial communities remain under-investigated. This study demonstrated that Bacillus velezensis TCS001 significantly inhibited P. cinnamomi ST402 growth in vitro, and achieved 71% efficacy in root rot disease management. Scanning electron microscopy (SEM) revealed that TCS001 fermentation filtrate induced mycelial deformities in P. cinnamomi. An analysis of α and β diversity indicated a significant impact of TCS001 on rhizosphere bacterial community richness and diversity, with minimal effects on the fungal community. Moreover, TCS001 altered the hickory rhizosphere microbiome co-occurrence network. The differential abundance analysis suggests that TCS001 promotes the recruitment of beneficial microbes associated with disease resistance, thereby suppressing disease development. These findings underscore the influence of TCS001 on the hickory rhizosphere microbiome in the presence of pathogens, providing valuable data for future research and the development of effective biocontrol strategies for hickory root rot.

Biological control is considered one of the most important methods for preventing and controlling the worldwide fungal disease gray mold, caused by Botrytis cinerea. Among the various agents used in biological control, actinomycetes represent a significant group of microorganisms that offer valuable resources for biocontrol strategies. In this study, a total of 132 actinomycetes, belonging to four genera (Streptomyces, Kitasatospora, Amycolatopsis, and Nocardia), were isolated from soil. Among the five media tested, ISP-2 and GS NO.1 media were found to be highly suitable for isolating actinomycetes. It is worth mentioning that the strain TCS21-117 displayed significant inhibitory effects against Botrytis cinerea and nine other pathogenic fungi. The strain TCS21-117 was identified as Streptomyces roietensis by its morphological characteristics and phylogenetic analysis of the 16S rRNA gene. The optimum culture conditions for the strain TCS21-117 were a potato dextrose broth medium at an initial pH of 8.0, a liquid volume of 125 mL in a 250 mL flask, 180 r·min⁻¹ at 28 °C, and an inoculum size of 1% for 7 days. Under these conditions, the inhibition rate against Botrytis cinerea was 93.31%, a significant increase (31.98%) as compared to the control. Notably, the antifungal compounds produced by the strain TCS21-117 exhibited strong stability across a range of temperatures, pH levels, and durations of storage and UV irradiation. This study showed that the Streptomyces roietensis strain TCS21-117 had strong inhibitory activity against Botrytis cinerea under optimized fermentation conditions, enriching the microbial resources for gray mold control.