To explore the mechanism of action of Bacillus velezensis against sweet cherry soft rot disease, the inhibitory effect of Bacillus velezensis KT against Rhizopus stolonifer LC-7 in vitro and in inoculated sweet cherry fruits, and the effect of B. velezensis KT on defense-related enzyme activities were investigated. Besides, the expression of genes related to secondary metabolite synthesis and biological control in B. velezensis KT during the interaction with R. stolonifer was also analyzed by transcriptomics. The results showed that the percentage inhibition of 1 × 10⁹ CFU/mL B. velezensis KT suspension against mycelial growth of R. stolonifer LC-7 was 87.12%, and the percentage of spore germination and germ length of R. stolonifer LC-7 in the presence of B. velezensis KT were 21.54% and 11.45 μm, respectively. At 48 h after being treated with 1 × 10⁹ CFU/mL B. velezensis KT suspension, the incidence of soft rot in cherry fruits was about 20% and was about 80% lower than that in the control group. B. velezensis KT suspension inhibited the activity of polyphenoloxidase (PPO) and lipoxidase (LOX), increased the activity of peroxidase (POD), phenylalanine ammonia lyase (PAL) chitinase (CHI) and β-1,3-glucanase (GLU), and improved disease resistance and antioxidant capacity in cherry fruits. It was observed by scanning electron microscopy that after co-cultured with B. velezensis KT, the morphology of the mycelia and spores of R. stolonifer LC-7 was distorted and malformed. Transcriptomic analysis showed that the expression of pksIJ in the biosynthetic gene cluster for antibiotic bacillaene and tuaAGE in the biosynthetic gene cluster for teichuronic acid were upregulated, and the differentially expressed genes were mainly concentrated in ribonucleoprotein complex assembly, subunit assembly and ribosomal assembly during biological processes. The B. velezensis KT could directly inhibit R. stolonifer LC-7 probably through nutritional and spatial competition and secreting anti-bacterial substances and could also induce disease resistance in sweet cherry fruits. The results showed that B. velezensis KT had an obvious control effect on sweet cherry soft rot caused by R. stolonifer LC-7, making it a potential biocontrol agent.

This novel study identifies the effective anti-inflammatory phenolic compounds in dandelion and provides mechanistic insights into their interactions with receptor proteins (toll-like receptor 4, TLR4; co-receptor myeloid differentiation protein-2, MD-2) using UHPLC-ESI-MS/MS, lipopolysaccharide (LPS)-stimulated THP-1 cell line, fluorescence quenching and anisotropy, molecular docking (single ligand and multi-ligand docking) and molecular dynamics simulation. A 50% aqueous methanol extract had a greater anti-inflammatory effect and higher chicoric acid content, compared with the 100% water and 100% methanol extracts. Chicoric acid, chlorogenic acid, methylophiopogonone A, caffeic acid, gallic acid monohydrate and 4'-O-demethylbroussonin A had relatively high binding energies and contents in all extracts. Chicoric acid competed with chlorogenic acid, 4'-O-demethylbroussonin A and quercetin for MD-2. Among dandelion’s phenolics, chicoric acid most effectively hindered TLR4-MD-2 complex formation, with a quenching constant of 0.62 × 10⁶ L/mol for MD-2 or TLR4 at 320 K, and binding energies of -6.87 and -5.97 kcal/mol, respectively, for MD-2 and TLR4.