Effects And Mechanism Of Arbuscular Mycorrhizal Fungi On The Growth And Competition Of Wedelia Trilobata

The world is facing an increasingly severe threat of plant invasion,causing economic losses or ecological disasters to biodiversity,agriculture,forestry,animal husbandry and fishery production,as well as human health.In this study,the malignant invasive weed Wedelia trilobata,widely distributed in southern China and causes serious harm,was taken as this research object.We conducted pot experiments to study the symbiosis between Wedelia trilobata and arbuscular mycorrhizal fungi(AMF),we also test the important roles of AMF in phosphorus resource utilization,growth and competition of W.trilobata.The important roles of root exudates of W.trilobata in plant growth,competition,and the symbiotic system of AMF were also studied.From the test of metabolomics,the in-depth effects of AMF on the growth and metabolism of W.trilobata were revealed.The main results of this study are as follows:1)The results showed that two AMF species,Funneliformis mosseae(FM)and Glomus versiforme(GV)could establish symbiosis relationships with W.trilobata.In particular,the GV infection rate is higher under low phosphorus nutrition,and GV has more significant promotion effect on the growth and the absorption of insoluble phosphorus.With the competition of its native congener plant,Wedelia chinensis(Osbeck.)Merr.,W.trilobata inhibits the growth of W.chinensis.Inoculation of GV during the interspecies competition has a higher infection rate of W.trilobata than that of the intraspecies competition treatment,and is beneficial to the growth and competitiveness of W.trilobata.However,GV has a low infection rate in W.chinensis,and it has no significant effects on its growth and competitiveness.2)The results showed that the addition of root exudates of W.trilobata increased the infection rate of GV in W.trilobata and significantly promoted its growth.At the same time,the root exudates of W.trilobata have a strong allelopathy inhibiting effect on native plants.The addition of root exudates and inoculation of GV are conduciveto the improvement of the competitiveness of W.trilobata.3)In metabolomics analysis,the metabolic composition of W.trilobata identified368 metabolites in 41 categories.Under the two treatments of inoculation and non-inoculation of GV,119 biomarker metabolites were screened,accounting for32.33% of the total identified metabolites.After GV inoculation,the relative content of 69 metabolites increased,accounting for 57.98% of the total biomarker metabolites,and the relative content of 50 metabolites decreased,accounting for 42.02% of the total biomarker metabolites.Among the biomarker metabolite,the plant hormones abscisic acid,ethylene and some amino acid metabolites changed significantly after inoculation with GV.The biomarker metabolite involve 53 metabolic pathways.These seven pathways with greater influence are Phenylalanine metabolism;Alanine,aspartate and glutamate metabolism;Arginine and proline metabolism;Glutathione metabolism;beta-Alanine metabolism;Pantothenate and CoA biosynthesis;Isoquinoline alkaloid biosynthesis.To sum up,it was suggested that the symbiosis between W.trilobata and AMF could significantly facilitate the plant growth and enhance the efficiency of insoluble phosphate uptake,which could promotes its competition with native plants.Root exudates of W.trilobata play an important role in the growth and symbiotic interaction between AMF and W.trilobata.AMF inoculation has effect on the metabolites and metabolic pathways of W.trilobata.All of the above results might be one of the important reasons why W.trilobata invades rapidly into new habitats and becomes the dominant species.