Effects Of Chlorpyrifos On Rice Plants And Rhizosphere Microenvironment Based On Metabolomics Technology

Pesticides can not only control crop diseases and pests,but also ensure high yield and high quality of crops.It is used for a long time and continuously remain and accumulate in soil,and the pesticides remaining in the environment are easy to migrate and accumulate to non-target organisms,thus causing ecological and environmental safety problems and even serious risks to the quality and safety of agricultural products.The abundant microbial community in the plant rhizosphere environment can improve the ability of plants to resist environmental stress,which plays an important role in the restoration of pesticide residues.However,the research on the interaction among pesticide-plant-rhizosphere environment is lacking.Metabolomics can elucidate the response of biological tissues to various stresses by detecting changes in metabolites.Therefore,based on the metabolomic analysis strategy and the combined application of multi-omics,this paper focuses on the interaction of pesticide-plant-rhizosphere environment to explore the response mechanism of pesticide spraying to rice plant physiology,root exudates and rhizosphere microorganisms.The main content and results obtained are as follows:(1)The mechanism of the effects of chlorpyrifos stress on the metabolism of rice plants was studied based on metabolomic methods.The metabolomic analysis showed that different doses of chlorpyrifos stress affected the physiological metabolism of rice plants,while the metabolic effects of stems,leaves and roots were different.Most of the amino acids and organic acid compounds in stems,leaves and roots gradually increased with the increase of chlorpyrifos stress,suggesting that amino acids as precursors play a key role in rice resistance to chlorpyrifos stress.The flavonoids in stems and leaves were significantly down-regulated after chlorpyrifos stress,and these substances can be used to remove reactive oxygen radicals produced by chlorpyrifos stress.Most of the flavonoids and lipids in root tissue gradually decreased with the increase of chlorpyrifos stress.It may be that both flavonoids and lipids can be released into the rhizosphere environment as energy substances or signal molecules to reshape the rhizosphere microbial community structure.It can recruit beneficial bacteria to stimulate the plant’s defense system and help the plant resist environmental stress.Metabolic pathway analysis showed that chlorpyrifos stress significantly affected the biosynthesis and metabolic pathways of most amino acids and organic acids in rice plants.(2)The effects of different doses of chlorpyrifos on rice root exudates and rhizosphere soil flora were studied based on the combination of metabolomics and microbiome.The results showed that chlorpyrifos stress significantly altered the metabolic profile of rice root exudates.After chlorpyrifos stress,most amino acids,organic acids,lipids and other substances increased significantly and were significantly positively correlated with the concentration of chlorpyrifos treatment.16 S r RNA gene sequencing technology found that chlorpyrifos stress can significantly affect the diversity and abundance of microbial communities in the rhizosphere and root surfaces of rice and some bacterial related to soil nutrient cycling,promoting plant growth and helping plants resist stress were increased significantly.Correlation analysis showed that most of the amino acids,organic acids,lipids and other substances in root exudates were significantly positively correlated with the beneficial flora in the rhizosphere and root surface of rice.It can be shown that chlorpyrifos remodels the bacterial community structure of rice rhizosphere and root surface by regulating the composition of rice root exudates.(3)The recruitment mechanism of key active components in root exudates of rice under chlorpyrifos stress to the beneficial rhizosphere bacteria HJY was studied based on metabolomic technology.A previous study found that the root exudates of rice had an obvious recruitment phenomenon to the strain HJY under chlorpyrifos stress.The rice root exudates under chlorpyrifos stress were used to culture the strain HJY for extracellular metabolism experiments.The metabolites that were significantly up-regulated in rice root exudates under chlorpyrifos stress and significantly down-regulated in the extracellular metabolism experimental group were screened out by metabolomics technology.The differential metabolites were identified as the key active components in rice root exudates,including phenylalanine,glutamic acid,linoleic acid,linolenic acid,arachidonic acid,choline,trigonelline and isomaltulose,etc.The chemotaxis of strain HJY to different key active components of rice root exudates was compared through qualitative and quantitative chemotaxis plate experiments.Quantitative chemotaxis experiments showed that the chemotactic responses of strain HJY to different active components were different,and the chemotactic responses of two lipids(linolenic acid and linoleic acid)were significantly stronger than other active components,suggesting that the Linolenic acid and linoleic acid were the key active components that recruit rhizosphere degrading bacteria.