Research On The Effect Of Intercropping On The Tea Plants Microbiome And Defense Against Toxoptera Aurantii

Tea tree is an important economic plant species in the tropicals and subtropicals of China,which is of great significance for farmers to increase their income and become rich.Toxoptera aurantii is one of the most serious pests of tea tree,which mainly damages on the tender leaves of tea tree and seriously affects the quality and yield of tea.The prevention and cure of Toxoptera aurantii mainly focuses on chemical control and physical control.Studies have shown that the diversity of aboveground plants can change the chemical defense substances of plants to enhance the resistance of Toxoptera aurantii,resulting in different quantity and quality of plant residues and root exudates,which affect underground processes.Whether plant diversity can enhance the ability of plants to resist pests by regulating underground processes is still rarely reported.Therefore,from the perspective of biodiversity,indoor potted plants of intercropping ways are used to study how reduces the harm of Toxoptera aurantii by analyzing the average growth of Toxoptera aurantii,changes of soil nutrients in tea plants,distribution of tea biomass,changes in the structure of tea microbial community(bulk soil-rhizosphere soil-root surface-root endosphere-phyllosurface bacteria)and the difference of specific soil extracellular enzyme activities in tea soil.The intercropping pattern was divided into tea trees +legumes(peanut),tea trees + grasses(maize),and tea trees + peanut + maize.Simultaneously,there were two treatment methods: inoculating Toxoptera aurantii and not inoculating Toxoptera aurantii.This paper reveals the mechanism of intercropping microorganism group against tea aphid was revealed,which provided theoretical basis for optimizing tea planting mode and improving tea yield and quality.The main results are as follows:Compared with tea trees of monoculture,the average daily growth of Toxoptera aurantii decreased significantly in maize + tea and peanut + tea intercropping.The way of intercropping increased root biomass and root shoot ratio of tea plants.Only monoculture way increased leaf biomass and the contents of N,P and K in leaf after Toxoptera aurantii infestation.The results showed that the intercropping of peanut + maize could resist the damage of Toxoptera aurantii by changing the biomass and nutrient distribution to a certain extent.Compared with tea trees of monoculture,different intercropping patterns significantly changed the abundance of soil bacteria,including Alicyclobacillus 、 Tumebacillus 、Streptomyces、Acidothermus、Candidatus-Solibacter、Acidibacter and so on.Under the stress of Toxoptera aurantii,intercropping increased the number of bacteria in the soil.However,the bacterial groups increased in different patterns were different.The intercropping pattern of peanut + tea increased the relative abundance of Acidothermus and Candidatus-Solibacter,the intercropping of maize + tea increased the relative abundance of Candidatus-Solibacter and Alicyclobacillou,the intercropping of peanut +tea + maize intercropping increased the relative abundance of Gemmatimona.Compared with the monoculture of tea tree,maize + tea intercropping significantly increased the activities of acid phosphatase and glucosidase,while all intercropping patterns increased the activities of peroxidase and polyphenol oxidase.The result of Toxoptera aurantii grazing was that it only increased the soil enzyme activity of tea monoculture.Soil enzyme activity is closely related to the changes of microbial groups and nutrients.The results showed that intercropping mode enhanced resistance to Toxoptera aurantii by increasing the turnover rate of nutrients and soil microbial beneficial bacteria.Compared with tea trees of monoculture,the relative abundances of Actinobacteriota and Firmicutes were mainly increased on the surface of tea roots,while the relative abundances of Actinobacteriota and Cyanobacteria were increased within root endospheres of tea.Under the stress of Toxoptera aurantii,intercropping increased the relative abundance of Chloroflexi and Patescibacteria on the root surface and the relative abundance of Candidatus-Koribacter,Paenibacillus and Acidothermu in intercropping was higher than that in monoculture.Compared with tea trees of monoculture,the abundance of Protebacteria was increased in all intercropping models.However,under the stress of Toxoptera aurantii,the abundance of Protebacteria was reduced in the other intercropping modes except tea trees of monoculture mode.At the genus level,the relative abundance of Bacillus,Alicyclobacillus was increased mainly by intercropping compared with tea trees of monoculture.The results showed that intercropping was more effective than monoculture in increasing the beneficial microorganisms of tea plant and resisting the stress of Toxoptera aurantii.The shared core microbial communities of leaf surface of tea plants were found in the effector soil-rhizosphere soil-root surface-root of tea plants,and there were differences in shared microbial groups between different planting patterns.The shared core microbial communities of phyllosphere of tea plants were found in the effector bulk soil-rhizosphere soil-root surface-root endosphere of tea plants,and there were differences in shared microbial groups between different planting patterns.Under the condition of not to inoculate Toxoptera aurantii,In the monoculture mode,most OTUs on the phyllosphere of tea plants shared with the effect bulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were 68.83%,66.53%,60.29%,38.06%,respectively.The main bacteria were Acidobacteriota(8.76%),Actinobacteriota(26.73%),Bacteroidota(2.31%),Chloroflexi(10.60%),Firmicutes(5.07%),Planctomycetota(2.76%),Proteobacteria(34.10%).In the model of peanut + tea,the OTU shared by tea phyllosphere and effect bulk soil-rhizosphere soil-root surface-root endosphere were 78.85%,74.35%,65.60% and 39.74%,respectively.The main bacteria were Acidobacteriota(8.04%),Actinobacteriota(32.43%),Chloroflexi(7.21%),Firmicutes(2.70%),Proteobacteria(36.94%).In the model of maize + tea,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were 69.38%,66.89%,57.40% and 40.27%respectively.The main bacteria were Acidobacteriota(7.44%),Actinobacteriota(31.21%),Bacteria(3.32%),Chloroflexi(9.87%),Firmicutes(9.64%),Myxococcota(3.51%),Proteobacteria(30.21%).In the model of peanut + maize + tea,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were 78.85%,74.36%,65.60% and 39.74%,respectively.The main bacteria were Acidobacteriota(8.90%),Actinobacteriota(30.14%),Bacteria(2.74%),Chloroflexi(10.96%),Firmicutes(8.90%),Myxococcota(2.74%)and Proteobacteria(28.08%).Under the stress of Toxoptera aurantii,the number and species of OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants were changed.In monoculture mode,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were 62.47%,59.97%,59.42%,39.47%.The main bacteria were Acidobacteriota(7.40%),Actinobacteriota(40.88%),Bacteria(0.73%),Chloroflexi(6.57%),Firmicutes(7.30%),Myxococcota(4.38%),Proteobacteria(22.63%).In the model of peanut + tea,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were70.98%,67.28%,69.54%,37.86%.The main bacteria were Acidobacteriota(7.69%),Actinobacteriota(42.31%),Chloroflexi(3.85%),Firmicutes(8.65%),Proteobacteria(29.81%).In the model of maize + tea,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were88.64%,76.48%,60.42%,46.24%.The main bacteria were Acidobacteriota(6.42%),Actinobacteriota(43.56%),Chloroflexi(8.62%),Firmicutes(7.66%),Planctomycetota(5.65%),Proteobacteria(24.44%).In the model of peanut + corn + tea,the OTU shared by tea phyllosphere and effectbulk soil-rhizosphere soil-root surface-root endosphere of tea plants within the OTU were 85.07%,76.47%,68.33%,55.43%.The main bacteria were Acidobacteriota(7.30%),Actinobacteriota(40.88%),Chloroflexi(6.57%),Firmicutes(7.30%),Myxococcota(4.38%),Planctomycetota(2.92%)and Proteobacteria(22.63%).The results showed that:(1)the mode of intercropping changed the microbial communities in effectbulk soil,rhizosphere soil,root surface,root endosphere and phyllosphere of tea trees,which may enhance the nutrient absorption of plant and the healthof soil and plant;(2)the model of intercropping increased the resistance of tea plants to Toxoptera aurantii by enhancing soil nutrient turnover and recruiting beneficial microbial communities;(3)maize + tea and peanut + tea had the strongest resistance to Toxoptera aurantii.