Studies On The Mechanism Of Allelopathic Inhibitory Effects Of Solidago Canadensis L. On Microcystis Aeruginosa

In recent years, the situation of eutrophication in drinking water source and frequent breakouts of harmful algal bloom is getting more and more serious, which does not only affect the balance of ecosystem, but also is a threat to the safety of water supply. Compared with physical and chemical algae control technologies, allelopathic algae control technologies show a distinctive competitive advantage, for the easy getting and being environmentally-friendly. However, this new algae control method is not yet widely used because of the uncertainty of inhibitory mechanism.Solidago canadensis L., as an important alien invasive plant in our country, has been reported that it may inhibit the growth of its neighbor species. In this subject, algal control was combined with Solidago canadensis L. utilization, and the inhibitory mechanisms of Solidago canadensis L. on Microcystis aeruginosa were studied.The results obtained were summarized as follows:Solidago canadensis L. strongly inhibited the growth of Microcystis aeruginos in some concentration ranges. The content of protein in Microcystis aeruginos cells decreased under the effect of the extracts of Solidago canadensis L.The extracts of Solidago canadensis L. damaged the cell structure, inclusion of algae leaked out, plasmolysis emerged,cell wall and cell membrane were broken off with organelle dissolved, leading to cell death finally.The extracts of Solidago canadensis L. affected the activity of SOD and CAT, increased the content of As A and GSH. The mechanism of generating and eliminating of ROS was affected, leading to an increase of ROS, which may damage the algae cells.The content of MDA increased under the effect of the extracts of Solidago canadensis L..The extracts of Solidago canadensis L. also changed the relative contents of saturated and unsaturated fatty acid, increased the membrane permeability.The extracts of Solidago canadensis L. damaged the phytochrome, leading to a decrease of phytochrome, especially Chl a and APC. Photosynthesis was also affected.There appeared to be some phenomenons which are similar to cell apoptosis in Microcystis aeruginos, indicating that the extracts of Solidago canadensis L. may induce apoptosis in Microcystis aeruginos. The toxicity tests showed that the growth and movement of daphnia magna and Danio rerio were hardly affected by the extracts of Solidago canadensis L. in some concentration ranges.The results indicated that the change of ROS content is the key to a series of changes in Microcystis aeruginos cells. ROS in Microcystis aeruginos cells increased under the effect of the extracts of Solidago canadensis L., which may cause following damage to the cells. That is the most important mechanism of allelopathic inhibitory effects of Solidago canadensis L. on Microcystis aeruginosa.