Collierbach1190

Ralstonia solanacearum (R. solanacearum) is one of the most devastating bacterial pathogens and leads to serious economic losses in crops worldwide. In this study, the antibacterial activities of novel plant-derived coumarins against R. solanacearum and their underlying mechanisms were initially investigated. The bioactivity assay results showed that certain coumarins had significant in vitro inhibitory effects against R. solanacearum. Notably, 6-methylcoumarin showed the best in vitro antibacterial activity with 76.79%. Interestingly, 6-methylcoumarin was found to cause cell elongation, disrupt cell division, and suppress the expression of the bacterial division protein coding genes ftsZ. Compared with the control treatment, the ∆ftsZ mutant inhibited bacterial growth and caused the bacteria to be more sensitive to 6-methylcoumarin. The application of 6-methylcoumarin effectively suppressed the development of tobacco bacterial wilt in pot and field experiments, and significantly reduced the bacterial population in tobacco stems. The control efficiency of 6-methylcoumarin treatment was 35.76%, 40.51%, 38.99% at 10, 11, and 12 weeks after tobacco transplantation in field condition. All of these results demonstrate that 6-methylcoumarin has potential as an eco-friendly and target specificity agent for controlling tobacco bacterial wilt.Imidacloprid is a neonicotinoid that targets sucking pests, such as aphids and the green leaf bug and has been widely applied in wheat fields to control wheat aphids in China. To investigate the involvement of miRNAs in imidacloprid resistance, we sequenced small RNA libraries of Sitobion miscanthi Fabricius, across two different treatments using Illumina short-read sequencing technology. As a result, 265 microRNAs (miRNAs), of which 242 were known and 23 were novel, were identified. Quantitative analysis of miRNA levels showed that 23 miRNAs were significantly up-regulated, and 54 miRNAs were significantly down-regulated in the nymphs of S. miscanthi treated with imidacloprid in comparison with those of the control. Modulation of the abundances of differentially expressed miRNAs, smi-miR-316, smi-miR-1000, and smi-miR-iab-4 by the addition of the corresponding antagomir/inhibitor to the artificial diet significantly changed the susceptibility of S. miscanthi to imidacloprid. Subsequently, the post-transcriptional regulatory mechanism was conducted, smi-miR-278 and smi-miR-316 were confirmed to be participated in the post-transcriptional regulation of nAChRα1A and CYP4CJ6, respectively. The results suggested that miRNAs differentially expressed in response to imidacloprid could play a critical regulatory role in the metabolism of S. miscanthi to imidacloprid.In the present study, a total of 21 natural or synthetic small-molecule organic acids were selected and determined for their activity against postharvest gray mold caused by B. cinerea. Overall, cuminic acid, which was extracted from the seed of Cuminum cyminum L, showed the most promising antifungal activity against B. cinerea both in vitro and in vivo. The study on action mechanism showed that cuminic acid could inhibit the development of sclerotia and the secretion of oxalic acid, destroy the cell membrane integrity, and down regulate the expression of several key genes involved in sclerotia development and pathogenicity of B. cinerea. click here Furthermore, cuminic acid could potentially reduce the degradation of TSS and TA content, while it had no significant effect on the weight loss, firmness, and VC content of apple and tomato. Importantly, cuminic acid could enhance the antioxidant enzyme activities of the fruits. All these results demonstrate the antifungal activity and highlight the great potential of cuminic acid as an alternative environmental-friendly agent for the control of postharvest gray mold both on fruits and vegetables.As one of the most important detoxification enzymes in insects, Glutathione S-transferases (GSTs) play key roles in insecticide resistance via direct metabolism and protection against oxidative stress induced by insecticide exposure. Insect GSTs are often considered as the phase II detoxification enzymes, they have potential function to metabolize fipronil as well as its fipronil's metabolites. In the fipronil-resistant Nilaparvata lugens strain G28, GSTs' inhibitor DEM (diethyl maleate) showed the optimal synergistic effects (5.73-fold), indicating the essential roles of GSTs in the resistance to fipronil in this insect species. Four GST genes, NlGSTs1, NlGSTs2, NlGSTe1 and NlGSTd1, were found over-expressed in G28 when compared to its relative susceptible counterpart strain S28. The roles of these four GSTs in fipronil resistance were confirmed via RNAi. The four GST genes were highly over-expressed in the midgut and/or fat body with detoxification action, which might provide more chances for insects to metabolize fipronil and its metabolites. Additionally, the higher induction levels in the GST gene expression by insecticides in the midgut and/or fat body compared to the whole insect also supported the significant roles of the four GSTs in the detoxification. Above all, the results provided evidences to understand the functions of GSTs in fipronil resistance in N. lugens, and gave a reference for other insects in fipronil resistance.Many pollinating insects expand their niche to adjacent agricultural areas and are, therefore, exposed to chemical insecticides. Acraea horta L. (Lepidoptera Nymphalidae) is a pollinator butterfly widely distributed in the Southern African region. The objectives of this work were to evaluate carbohydrate, lipid and chemical elements in the hemolymph of A. horta exposed to pyriproxyfen, a juvenile hormone analog (JHA). Last instar larvae (L6 day 1 or day 2) were topically exposed to an aqueous solution of pyriproxyfen (100 μg of the active ingredient per insect) or to diluent (control group). Hemolymph was collected after adult eclosion to determine total carbohydrate and lipid concentrations in the control group lipids were present in lower concentrations than carbohydrates and there was no significant difference in metabolite levels between sexes; a similar pattern with similar levels were measured in the treated group, except that lipid concentrations in treated males were lower, and carbohydrate concentrations in treated females were lower than the control values.