Root Exudates Mediates Interaction Between AMF And Invasive Plants

The invasion of exotic plants often exhibits destructive effects on environment and biodiversity,as well as human health and economy,which has become an urgent problem to be solved.The interaction between invasive plants and arbuscular mycorrhizal fungi(AMF)has received a lot of attention and become a core issues in the field of invasion ecology.Previous studies showed that invasive plants were typically more colonized than native ones,which play vital roles in the invasion success of exotic plants.Root exudates are the key factors that affect the interaction between soil microbes and invasive plants.However,it's undefined that the interaction mechanism of invasive plants and AMF mediated by root exudates.Therefore,exploring how root exudates mediates the interaction between invasive plants and AMF will assist to better understand the contribution and function of AMF in the process of plant invasion,revealing the environmental adaptation strategies and mechanisms of invasive plants under the new environment and providing new insights into management of invasive plants.To address this question,this experiment selected multiple pairs of invasive plants and their phylogenetically related native plants as focal species to examine and compare AMF inoculation on growth of invasive and native species,difference in AMF colonization between invasive and native species,effects of root exudates elimination and addition on AMF colonization between invasive and native species,and ecological effects of different metabolites on AMF spore germination through common garden experiment and laboratory experiment.The main methods and results are present below:(i)Seven pairs of invasive and phylogenetically related native species were subjected to two AMF treatments,each with control(no AMF inoculation)and AMF inoculation,to compare the effects of AMF on plant performance.AMF inoculation promoted the biomass of both invasive and native plants,but the positive effects was greater on invasive plants than native ones.(ii)Seven pairs of invasive and phylogenetically related native species were subjected to two activated carbon(AC)treatments,each with control(no AC addition)and AC inoculation,to test the effects of root exudates on the interaction of AMF with invasive and native plants.With AC addition,the biomass and AMF colonization were similar between invasive and native species,but the biomass and AMF colonization were higher than native plants in the absence of AC.(iii)To explore the effects root exudates addition on interaction between invasive and native plants,seven pairs of invasive and phylogenetically related native species were selected as focal species and subjected to three treatments,including water addition,root exudates addition from same species,and the other species in the pairs.For native species,root exudates addition from same species marginally increased their biomass and has no effects on AMF colonization,the reserved pattern was true for root exudates from invasive species.For invasive species,root exudates addition from same species significantly promoted their biomass and AMF colonization,and the opposite was true for root exudates from native species.Therefore,root exudates play key roles in the interaction between invasive plants and AMF.(iv)To test the difference in the interaction of AMF with invasive and native species under different growth periods,and difference in root exudates and their effects on AMF spore germination,we selected 21 pairs of invasive and native species as focal species to determine their difference in AMF colonization and root exudates at 30,60 and 90 days.Invasive plants grew larger and had higher AMF colonization than native species across all grow stages.The inorganic and total carbon content in root exudates from invasive plants were greater than native plants,and organic content and quercein in root exudates from invasive plants were higher than native species at 30 and 60 days,but was similar for both species at 90 days,and the opposite pattern was true for kaempferol.In vitro experiment,quercetin addition significantly promoted AMF spore germination at any concentration;Kaempferol addition at a concentration of 0.10 ppm had a greater stimulate effects on AMF spore germination that 1.00 ppm and 0.01 ppm did.Isoquercitrin addition significantly promoted AMF spore germination at any concentration,and isoquercitrin addition at a concentration of 0.10 ppm had a greater stimulate effects on AMF spore germination that 1.00 ppm and 0.01 ppm did.In summary,the results from multiple paired species showed that invasive species as a whole had a clear higher AMF colonization than phylogenetically related native species and root exudates had profound effects in the processes.In addition,the results indicated that the higher organic carbon contents and quercetin in root exudates released by invasive plant than native plants may be responsible for greater AMF colonization than native species.These findings together provided substantial evidence that difference of specific components in root exudates may results in different association strategies of AMF with native and invasive plants,which may in turn facilitate invasive plants outgrow native plants.