Inhibition Of Aqucous Extracts Of Wetaland Herbaceous Plants On Phaeocystis Globosa

Red tides are now a recurring problem worldwide,which profoundly causes great impacts on marine ecosystems,fisheries,aquaculture,aquatic recreation,and human health.The frequent outbreaks of Phaeocystis globosa?P.globosa?in the South China Sea have caused much attention in recent decades.Therefore,numerous algicidal materials and technologies have been developed.Given the strong adaptive capacities of some microalgae species,the ecological safety for non-targeted microalgae or aquatic animals,and the resources of plants,exploring more plants is crucial.Since red tides are rare in the adjacent waters of mangroves,and the usage of wetland herbaceous plants for controlling microalgae becomes the focus of the present study.In this study,several common herbaceous plants in the Qi'ao island,Guangdong Province,China,were sampled for screening the best algicidal species,and the algicidal component of the aqueous extracts was identified.Meanwhile,the growth curve,photosynthetic efficiency of PS?,cell ultrastructure and transcript expression were tested.In the present study,the preliminary analysis,monitoring the algicidal component of the aqueous extracts on the physiological progression of microalgae,was conducted.The results showed that?1?the Cyperus rotundus?C.rotundus?exhibited the best algicidal effect among six wetland herbs,and C.rotundus aqueous extracts showed different inhibition on the growth of P.globosa following the exposure to set concentration range(1,2,4,8 and 16 g·L^-1),and the inhibition rate gradually increased over time in the experimental process,and the effective dose of suppressing P.globosa was?4 g·L^-1 which was consistent with relative inhibition rate??87%?;?2?high concentration of C.rotundus aqueous extracts caused great effect on the physiological progression which consistent with the decrease chlorophyll a content,the decrease of PS?photosynthetic efficiency and the damage of cell membrane system;?3?the UPLC-HRMS analysis exhibited that phenolic acids were the main algicidal component in the C.rotundus aqueous extracts with the highest concentration of quinic acid;?4?the algicidal effect of single phenolic acid was limited based on the quinic acid test,and the algicidal effect of C.rotundus aqueous extracts might be the results from the synthetical effect of all phenolic acids identified in the extracts;?5?The transcriptome results of P.globosa showed that quinic acid mainly affected the transcriptional expression of different organelles,protein binding and structural constituent of ribosome.The purpose of this study was to explore the inhibition of aqueous extracts from six common wetland herbs on P.globosa.By comparing the inhibition rate,effective dose and EC₅₀,the C.rotundus aqueous extracts exhibited the best algicidal effect among six collected plants.The physiological process of P.globosa was further explored to understand the algicidal mechanism induced by C.rotundus aqueous extracts.Then,the algicidal active components of the C.rotundus aqueous extracts were isolated and identified,and the molecular mechanism of the active components was explored to further clarify the inhibition of algicidal substances on the expression of functional genes.The present study facilitated the practice application of C.rotundus aqueous extracts and provide a scientific basis and a new idea for the prevention of red tide.