Roles of endophytic fungi in medicinal plant abiotic stress response and TCM quality development

Medicinal plants,as medicinal materials and important drug components,have been used in traditional and folk medicine for ages.However,being sessile organisms,they are seriously affected by extreme environmental conditions and abiotic stresses such as salt,heavy metal,temperature,and water stresses.Medicinal plants usually produce specific secondary metabolites to survive such stresses,and these metabolites can often be used for treating human diseases.Recently,medicinal plants have been found to partner with endophytic fungi to form a long-term,stable,and win-win symbiotic relationship.Endophytic fungi can promote secondary metabolite accumulation in medicinal plants.The close relationship can improve host plant resistance to the abiotic stresses of soil salinity,drought,and extreme temperatures.Their symbiosis also sheds light on plant growth and active compound production.Here,we show that endophytic fungi can improve the host medicinal plant resistance to abiotic stress by regulating active compounds,reducing oxidative stress,and regulating the cell ion balance.We also identify the deficiencies and burning issues of available studies and present promising research topics for the future.This review provides guidance for endophytic fungi research to improve the ability of medicinal plants to resist abiotic stress.It also suggests ideas and methods for active compound accumulation in medicinal plants and medicinal material development during the response to abiotic stress.

Interactions between H_(2)O_(2)and dissolved organic matter during granular activated carbon-based residual H_(2)O_(2)quenching from the upstream UV/H_(2)O_(2)process

Granular activated carbon(GAC)filtration can be employed to synchronously quench residual H_(2)O_(2)from the upstream UV/H_(2)O_(2)process and further degrade dissolved organicmatter(DOM).In this study,rapid small-scale column tests(RSSCTs)were performed to clarify the mechanisms underlying the interactions between H_(2)O_(2)and DOM during the GAC-based H_(2)O_(2)quenching process.It was observed that GAC can catalytically decompose H_(2)O_(2),with a long-lasting high efficiency(>80%for approximately 50,000 empty-bed volumes).DOM inhibited GAC-based H_(2)O_(2)quenching via a pore-blocking effect,especially at high concentrations(10 mg/L),with the adsorbed DOM molecules being oxidized by the continuously generated·OH;this further deteriorated the H_(2)O_(2)quenching efficiency.In batch experiments,H_(2)O_(2)could enhance DOM adsorption by GAC;however,in RSSCTs,it deteriorated DOM removal.This observation could be attributed to the different·OH exposure in these two systems.It was also observed that aging with H_(2)O_(2)and DOM altered the morphology,specific surface area,pore volume,and the surface functional groups of GAC,owing to the oxidation effect of H_(2)O_(2)and·OH on the GAC surface as well as the effect of DOM.Addi-tionally,the changes in the content of persistent free radicals in the GAC samples were insignificant following different aging processes.This work contributes to enhancing understanding regarding the UV/H_(2)O_(2)-GAC filtration scheme,and promoting the application in drinking water treatment.