Influence of flavonoids from Sedum aizoon L. on mitochondrial function of Rhizopus nigricans in strawberry.

Rhizopus nigricans (R. nigricans), one of the fungi that grows the fastest, is frequently discovered in postharvest fruits, it's the main pathogen of strawberry root rot. Flavonoids in Sedum aizoon L. (FSAL) is a kind of green and safe natural substance extracted from Sedum aizoon L. which has antifungal activity. In this study, the minimum inhibitory concentration (MIC) of FSAL on R. nigricans and cell apoptosis tests were studied to explore the inhibitory effect of FSAL on R. nigricans. The effects of FSAL on mitochondria of R. nigricans were investigated through the changes of mitochondrial permeability transition pore(mPTP), mitochondrial membrane potential(MMP), Ca2+ content, H2O2 content, cytochrome c (Cyt c) content, the related enzyme activity and related genes of mitochondria. The results showed that the MIC of FSAL on R. nigricans was 1.800 mg/mL, with the addition of FSAL (1.800 mg/mL), the mPTP openness of R. nigricans increased and the MMP reduced. Resulting in an increase in Ca2+ content, accumulation of H2O2 content and decrease of Cyt c content, the activity of related enzymes was inhibited and related genes were up-regulated (VDAC1, ANT) or down-regulated (SDHA, NOX2). This suggests that FSAL may achieve the inhibitory effect of fungi by damaging mitochondria, thereby realizing the postharvest freshness preservation of strawberries. This lays the foundation for the development of a new plant-derived antimicrobial agent.

A Phylogenetic and Taxonomic Revision of Discula theae-sinensis, the Causal Agents of Anthracnose on Camellia sinensis.

Tea (Camellia sinensis (L.) Kuntze) is one of the most important economic plants in China, and has many benefits for human health. Anthracnose is one of the most serious diseases of tea in China, and control of the fungus is important since most Chinese cultivars are susceptible to it. The agent of tea anthracnose was initially described as Gloeosporium theae-sinensis I. Miyake in Japan, which was later transferred to Discula, but this taxonomic position remains problematic. To shed light on these taxonomic and phylogenetic issues, the tea anthracnose pathogens were re-studied. Combining the morphological characteristics and a multigene phylogenetic analysis of nrITS, nrLSU, rpb2, and tef1 sequence data, a new genus Sinodiscula was proposed to accommodate the causal fungi of tea anthracnose, including a new species Sinodiscula camellicola and a new combination Sinodiscula theae-sinensis. Furthermore, the pathogenicity of the pathogens was determined according to Koch's postulates. This study thoroughly resolves the long-standing taxonomic and phylogenetic problems of the tea anthracnose pathogens.

The regulation of Cytochrome f by mannose treatment in broccoli and its relationship with programmed cell death in tobacco BY-2 cells.

It is well established that programmed cell death (PCD) occurred in broccoli during postharvest senescence, but no studies have been conducted on the regulation of broccoli cytochrome f by mannose treatment and its relationship with PCD. In this study, we treated broccoli buds with mannose to investigate the changes in color, total chlorophyll content, gene expression related to chlorophyll metabolism, chloroplast structure, and cytochrome f determination during postharvest storage. In addition, to investigate the effect of cytochrome f on PCD, we extracted cytochrome f from broccoli and treated Nicotiana tabacum L. cv Bright Yellow 2 (BY-2) cells with extracted cytochrome f from broccoli at various concentrations. The results showed that cytochrome f can induce PCD in tobacco BY-2 cells, as evidenced by altered cell morphology, nuclear chromatin disintegration, DNA degradation, decreased cell viability, and increased caspase-3-like protease production. Taken together, our study indicated that mannose could effectively delay senescence of postharvest broccoli by inhibiting the expression of gene encoding cytochrome f which could induce PCD.

Inactivation of antibiotic resistant bacteria by Fe3O4 @MoS2 activated persulfate and control of antibiotic resistance dissemination risk.

Antibiotic resistance poses a global environmental challenge that jeopardizes human health and ecosystem stability. Antibiotic resistant bacteria (ARB) significantly promote the spreading and diffusion of antibiotic resistance. This study investigated the efficiency and mechanism of inactivating tetracycline-resistant Escherichia coli (TR E. coli) using Fe3O4 @MoS2 activated persulfate (Fe3O4 @MoS2/PS). Under optimized conditions (200 mg/L Fe3O4 @MoS2, 4 mM PS, 35 °C), TR E. coli (∼7.5 log CFU/mL) could be fully inactivated within 20 min. The primary reactive oxygen species (ROS) responsible for TR E. coli inactivation in the Fe3O4 @MoS2/PS system were hydroxyl radicals (•OH) and superoxide radicals (•O2-). Remarkably, the efflux pump protein was targeted and damaged by the generated ROS during the inactivation process, resulting in cell membrane rupture and efflux of cell content. Additionally, the horizontal transmission ability of residual antibiotic resistance genes (ARGs) harboring in the TR E. coli was also reduced after the inactivation treatment. This study offers an efficient approach for TR E. coli inactivation and substantial mitigation of antibiotic resistance dissemination risk.

Mucoadhesive and thermosensitive Bletilla striata polysaccharide/chitosan hydrogel loaded nanoparticles for rectal drug delivery in ulcerative colitis.

Ulcerative colitis (UC) is a chronic disease with diffuse mucosal inflammation limited to the colon. A topical drug delivery system that could be facilely performed and efficiently retained at colon are attractive for clinical ulcerative colitis treatment. Herein, a novel platform for rectal administration of thermosensitive hydrogel co-loaded with nanoparticles to treat ulcerative colitis was developed. Thiolated-hyaluronic acid was synthesized, and prepared nanoparticles with zein and Puerarin. And the Bletilla striata polysaccharide with colonic mucosa repair effect was oxidized, and mixed with chitosan and ß-sodium glycerophosphate to prepare thermosensitive hydrogel. Thermosensitive hydrogels were combined with nanoparticles to investigate their mucosal adhesion, retention, and permeability, as well as their therapeutic effects on ulcerative colitis. Thiolated-hyaluronic acid nanoparticles had good stability, and could be quickly converted into hydrogel at body temperature when combined with thermosensitive hydrogel. The nanoparticles-loaded thermosensitive hydrogel also was excellent at mucosal penetration, enhancing the retention time of drugs in colon, and effectively controlling drug release. In vivo ulcerative colitis treatment revealed that the nanoparticles-loaded hydrogel significantly repaired the colonic mucosa and inhibit colonic inflammation. Therefore, the thermosensitive hydrogel co-loaded nanoparticles will have a promising application in effective treatment of ulcerative colitis by topical administration.