Studies On Physiological And Metabolic Characteristics Of Roots Of Invasive Plant Solidago Canadensis L.

Solidago canadensis L.is a polyploid complex plant of the species of Solidago,composite family and it’s native to North America.Due to its various reproductive methods,strong resistance,strong allelopathy,as well as the effects of external environment and human activities,S.canadensis has successfully invaded Asia,Europe,Australia and other areas,including China.It has become a worldwide invasive weed,and cause a series of damage to the ecological environment they invaded.Different ploidy of S.canadensis showed significant differences in phenotype and invasiveness,and this paper studied diploid(scutellaria,cultivated)and hexaploid(strong invasive ability)roots of S.canadensis.The study of scientific issues related to physiological metabolism will provide a basis for understanding the differences in physiological and metabolic mechanisms of different ploidy S.canadensis.The experimental material in this paper is the root of diploid Canadian goldenrod taken from Kunming and the root of Hexaploid Canadian goldenrod taken from Wuhan.Root samples were processed and metabolome analyzed using LC-MS,and differences were identified using PCA and PLS-DA.Finally,a large number of metabolites and their related metabolic pathways differentially expressed in diploid and hexaploid Canadian goldenrod leaves were screened.The KEGG pathway enrichment analysis was performed on the differentially expressed metabolites and metabolic pathways using relevant networks.In addition,based on the analysis of standard information,the obtained metabolite and metabolic pathway enrichment results were combined and analyzed to obtain the data of the metabolome in the roots of S.canadensis as a whole.The main findings are as follows:A total of 15,800 species were identified in positive ion mode,and a total of 6,658 species were identified in negative ion mode.Diploids were used as a reference to screen and analyze the metabolites of the hexaploid Canadian goldenrod,and the differences between the two were identified using PCA and PLS-DA.With VIP ≥ 1,fold change ≥ 1.2 or ≤ 0.8333 and q-value < 0.05 as the screening conditions,5149 different substances were obtained in positive ion mode(including 2829 up-regulation and 2320 down-regulation),2294 kinds of different substances were obtained in the negative ion mode(including 1191 up-regulated and 1103 down-regulated).All the different substances obtained were analyzed by KEGG pathway analysis,and the data of the annotated substances were made data filtering.In positive ion mode,the final identified differential metabolites were 2,093 species(of which 1243 were up-regulated and 850 were down-regulated).All 2,093 differential metabolites were classified and annotated with the MBRole 2.0 website,and a total of 460 metabolites were annotated.These annotated differential metabolites can be broadly classified into six categories,namely Terpenoids,Phenylpropanoids and related compounds,Alkaloids,and Polyketides.Amino acid derivatives other than alkaloids and Chromones.In addition to chromones,other substances all have been reported to have antioxidant,free radical scavenging activities or allelopathy.The enrichment analysis was used to the noted differential substances and their involved metabolic pathways according to the KEGG annotation,and a total of 108 differential metabolic pathways have been enriched.Using p-value <0.05 as the standard,15 differential metabolic pathways were screened,namely Diterpenoid biosynthesi,Arachidonic acid metabolism,Mononotpenoid biosynthesis.Isoflavonoid biosynthesis,Biosynthesis of secondary metabolites,sesquiterpenoids and triterpenoid biosynthesis,Limonene and pinene degradation,linoleic acid metabolism,flavonoid biosynthesis,Phenylpropanoid biosynthesis,alpha-Linolenic acid metabolism,anthraquinones,Diphenylheptanoid and gingerol biosynthesis,Flavone and flavonol biosynthesis,ubiquinone and other terpenoids-biosynthesis Ubiquinone and other terpenoid-quinone biosynthesis,plant hormone signal transduction.It has been found that the S.canadensis can increase the accumulation of metabolites with antioxidant activity,free radical scavenging activity or allelopathy,through extensive regulation of the above pathways,to improve their defense,anti-adversity ability and invasive ability.The physiological changes of S.canadensis under salt and heat stress were studied.It was found that the initial activities of CAT,SOD and POD decreased under salt stress,and the MDA content increased to a certain threshold with the increase of salt stress time,which caused the response of cell defense in root.Through the regulation of the enzyme system and the non-enzymatic system,the activity of CAT,POD and the content of stress-resistant protein are increased in order to remove the toxic substances accumulated in the plant and resist external invasion.However,SOD has been degraded due to the synergistic effect of non-enzymatic systems such as MDA and protein.From this,we can speculate that the root cells of S.canadensis is should not fully coordinate the CAT,POD and SOD under the salt stress applied in this experiment.The main enzymes are CAT and POD.In addition,non-enzymatic systems such as MDA are also involved in defense.The root has certain adaptability to heat stress at 42℃,and the physiological response is not obvious in a short time.Physiological changes caused by direct heat stress in plants take some time to be communicated to the roots,and degradation of stress-related proteins may be present in the process.