Study On The Secondary Metabolites And Allelopathy Of Chamaenerion Angustifolium(L.) Scop.Syn. And Dictamnus Dasycarpus Turca.

Allelopathy refers to the direct or indirect harmful or beneficial effects of plants or microorganisms on themselves and other plants by releasing secondary metabolites into the environment.Allelopathic secondary metabolites,also known as allelopathic substances,are the material basis for plants or microorganisms to exert allelopathic effects,which affect other plants at different growth and development stages.To search for allelopathic substances is a new direction for the research and development of botanical pesticides.In this study,the allelopathic effects of rosebay willowherb(Chamaenerion angustifolium(L.)Scop.Syn.)and densefruit pittany root-bark were studied to find their potential allelopathic secondary metabolites.This experiment studies the allelopathy of the water extracts of rosebay willowherb flowers,stems,capsularfruits and leaves on the seed germination and growth of the plant lettuce L.sativa.The germination rate,germination potential and germination index are used to investigate the effec ts of different extracts on seed germination.Use seedling radicle length,hypocotyl length and biomass as indicators to investigate the effects of different extracts on seed growth;use scanning electron microscopy and transmission electron microscopy techniques to observe and compare the radicle tip cell morphology and intracellular after treatment with allelopathic extracts changes in tissue structure,confocal fluorescence microscopy technology was used to observe and compare the cumulative changes of a ctive oxygen in radicle tissue after treatment with allelopathic extracts.HPLC analysis found that the main secondary metabolites of willowherb leaves were gallic acid,methyl gallate,caffeic acid,ellagic acid,quercitrin,hyperoside and isoquercitrin,and the allelopathic effects of potential allelochemicals were studied.The results show that gallic acid,methyl gallate and caffeic acid are their potential allelochemicals,which have inhibitory effects on four weeds,L.perenne,E.crusgalli,B.pilosa and A.retroflexus.In this experiment,modern separation technology was used to separate the potential allelochemicals in the limonoids and alkaloids in the densefruit pittany root-bark,and the radicle length was used as an indicator to study its allelo pathy.Four compounds were isolated from limonoids and identified as fraxinellone(1),obacunone(2),limonin(3),limonin phenol(4).Among the limonoids compounds,fraxinellone and limonin phenol in the range of 1-333 μM inhibit the radicle growth of L.sativa seedlings,and fraxinellone,limonin and limonin phenol have hormesis effects on L.esculentum and promote the growth of radicle.Four compounds were isolated from total alkaloids and identified as dictamnine(5),robustine(6),γ-fagarine(7),iso-γ-fagarine(8).The alkaloids of densefruit pittany root-bark have a certain allelopathic inhibitory effect on the growth of L.sativa,L.esculentum,L.perenne,E.crusgalli,B.pilosa and A.retroflexus radicles.The strongest allelopathic inhibitory effect is dictamnine,followed by γ-fagarine,iso-γ-fagarine,and robustine.Using four indicators of ROS,free proline content,cell viability and mitosis,B.pilosa as a recipient plant,to study the allelopathy mechanism of dictamnine.The results showed that with the increase of the concentration of dictamnine,the accumulation of active oxygen increased,the content of free proline increased,cell viability decreased significantly,and the cells in the division phase dec reased significantly.Dictamnine may affect cell viability and inhibit mitosis by inducing a large accumulation of ROS in recipient plants,thereby inhibiting plant growth.The experimental results of this subject show that both Chamaenerion angustifolium(L.)Scop.Syn.and Dictamnus dasycarpus Turca.have strong allelopathic effects.They have a certain development value as plant resources for the development of natural herbicides.