Ageratina Adenophora Accumulate Beneficial Bacteria To Release Effects Of Its Own Alleopathic Auto-toxicity

Many exotic species exudate allelochemicals to get advantages over their new neighbors,but many allelopathicals are autotoxic to themselves or to their new generations.Allelochemicals may be degraded by soil biota or have been adapted by plants.This study was to test whether Ageratina adenophora accumulated beneficial bacteria to release the auto-toxic allelopathic effects of 2-coumaric acid glucoside isolated from itself.The main results are as follows:1)The results showed that positive plant-soil feedback(PSF)for seed emergence of Ageratina occurred in invaded soil and no significantly negative PSF for seed germination and seedling growth of Medicago sativa,Poa annua and Eupatorium lindleyanum both in native soil and invaded soil.2)Both numbers of Bacillus subtilis and Bacillus megatherium decrease with distance increase from A.adenophora,namely,numbers of B.subtilis and B.megatherium are most in invaded soil,middle in mixed and native soil;and least in bare soil.3)Growth of B.subtilis and B.megatherium are not sencentive to the allelochemical 2-coumaric acid glucoside.4)The allelochemical showed strong allelopathic or auto-toxic effects on seed germination and seedling growth of the four target species both in solution and soil.5)Adding B.subtilis,B.megatherium or both the bacterium could alleviate the allelopathic effects on seed germination and seedling growth of the four target species whether in solution or in soil,because these bacteria could degrade the allelochemical 2-coumaric acid glucoside.6)Analysis of High Performance Liquid Chromatography showed that adding B.subtilis,B.megatherium or both the bacterium could degrade the allelochemical 2-coumaric acid glucoside within short time(48-96 h).In summary,Ageratina accumulated soil benefical B.subtilis and B.megatherium providing positive PSF to its seed emergence and alleviating the allelopathic effects on its own seed germination and seedling growth by detoxification to obtain advantages over its native competitor,and then facilitated its invasion success.