Studies On The Potential Suitable Distribution Areas And Chemical Constituents Of The Invasive Plant Solanum Rostratum

Biological invasion has become one of the most serious ecological and environmental problems in the world.Alien species invasion affect individual,population,community and ecosystem in invading area,causing huge economic losses to human society.Besides studying the mechanisms underlying biological invasions,how to develop effective strategies to prevent spread of invasive organisms and utilize invasive organisms have become the hot spots of current research of biology.Solanum rostratum is native to North America.Because of its strong adaptability and reproduction,S.rostratum has spread quickly in China since it was first found in Liaoning Province,Northeast China in 1981.It has been listed on the fourth batch of invasive alien species by Ministry of Ecology and Environment in China.I first studied its potential suitable distribution areas in China using species distribution models(SDMs)and the effects of climate warming on its potential distribution in the future.Then I isolated and identified its secondary metabolites by using various chromatographic and spectroscopic methods.I selected 22 climate variables,11 soil variables,3 topography variables,and 18 environment variables from the background information on the 3643 sites where S.rostratum was found,and then build 8 common species distribution models(SDMs)in Biomod2 using these data.Then,I selected 5 better SDMs based on true skill statistic and the area under receiver operating character curve,and constructed 2 ensemble models using them.Finally,I compared simulation effects of 8 single models and 2 ensemble models.The results indicated that the random forest(RF)was the best model,for which TSS and AUC reached to 0.892 and 0.979,respectively,followed by the 2 ensemble models.The surface range envelope performed the worst.The suitable distribution of S.rostratum was mainly affected by soil factors such organic carbon content in fine soils and climate factors such as temperature seasonality and isothermality,but less by topography factors.I projected RF in map of China under current environments based on space latitude and longitude,and made a hierarchical map to show potential distribution of S.rostratum.The area with high suitability for S.rostratum was 1.2 million km2 in China,and the area with moderate suitability was 1.88 million km2,accounting for 31% of China's land area in total.Shandong,Shanxi,Henan and Shaanxi were all suitable for S.rostratum,where no S.rostratum had been found.Thus,these areas should be protected in advance.S.rostratum invaded in Beijing,Tianjin,Hebei,Liaoning,Jilin and Inner Mongolia,where there were still more spaces for spread and the possibility of large-scale outbreaks.I projected RF in map of China under the simulated 2050 s environments based on space latitude and longitude,and found that the area with high suitability for S.rostratum disappear in 2050 in China,but there were still large areas with low suitability for this invader.The results provided a scientific basis for monitoring and controlling S.rostratum.By the means of various chromatographic methods,25 compounds were isolated from above-ground parts of S.rostratum.Chemical structures were identified for 14 compounds using various spectroscopic methods,combined with the physical and chemical properties of the compounds.There were 10 alkaloids(1-10),1 coumarin(11)and 3 terpenoids(12-14).Among them,phenylethylamine A(1)was a new one.1Hindole-3-carboxaldehyde(9)and 3-(2-Hydroxyethyl)indole(10)were isolated from the S.genus family for the first time.3-(4-hydroxyphenyl)-N-[2-(4-hydroxyphenyl)-2-methoxyethyl]-acrylamide(2),N-trans-pcoumaroyloctopamine(3),N-trans-P-coumaroyl-3',4'-dihydroxyphenylethylamin(4),trans-Ncoumaroyltyramine(5),N-cis-p-coumaroyloctopamine(6),cis-N-phydroxycinnamoyl-7'-methoxyethyltyramine(7),cis-N-coumaroyltyramine(8),1H-indole-3-carboxaldehyde(9),3-(2-Hydroxyethyl)indole(10),Scoparone(11),dehydrocarissone(12),(+)-dehydrovomifoliol(13)and Loliolide(14)were isolated from S.rostratum for the first time.This study enriched the chemical compounds of S.rostratum,and provided information for comparing chemicals of S.rostratum from different distribution areas,as well as the possible utilization of the invader.