Identification Of Cd Tolerance Of Verbena Bonariensis And Sequencing Of Transcriptome Under Cd Stress

In recent years,the heavy metal pollution in soil has become one of the urgent environmental problem in the world,especially the heavy metal Cd,great harm to the environment,in addition to pose a serious threat to plant growth,but also can be enriched through the food chain in the human body,affect people's health,even life-threatening.At present,the use of herbaceous and woody plants to repair heavy metal pollution is an important technology for the restoration of soil.Verbena bonariensis has strong adaptability,strong growth and high ornamental value.Especially with the popularity of sightseeing farms,it has great potential for development,and has strong stress resistance and large biomass.It is an ideal soil remediation material.In this study,the germination rate,morphological index,physiological index,biomass accumulation and heavy metal accumulation characteristics of Verbena bonariensis were determined and analyzed under different concentrations of heavy metal Cd,and their Cd tolerance was studied.In addition,through high-throughput sequencing,construct theVerbena bonariensis transcriptome database in 100mg/kg under Cd stress and analysis based on sequence annotation,to study the molecular mechanism of internal Cd transport and detoxification,and provide valuable reference for the defense strategy of Cd after Verbenaceae potential discovery.The main results are as follows:1.Using Petri dish paper germination effects of heavy metal Cd on the germination of Verbena bonariensis seeds under the same culture conditions,through the observation of Verbena bonariensis germination in different concentrations of Cd records and survival analysis,found that the germination tolerance of critical Cd concentration is 20mg/L,under this concentration,seedlings can still germinate and the normal growth,showing tolerance to Cd.2.In different concentrations of heavy metal Cd under soil culture of Verbena bonariensis seedlings of different treatment time of Verbena bonariensis were morphological index,physiological index,biomass accumulation,accumulation characteristics of heavy metals determination and analysis,draw the conclusion: Verbena bonariensis does not belong to a Cd hyperaccumulator,but has a strong absorption of Cd ability and resistance to Cd,it belongs to the Cd tolerance of plants.The growth of Verbena bonariensis is rapid,its biomass is large and it has strong Cd resistance.It has great potential application value in the remediation of Cd pollution.3.The transcriptional Bank of Verbena bonariensis root under 100mg/kgCd concentration stress was constructed and sequenced.After screening data,we obtained 55,962,351 clean and 61,462,567 Q30 reads 93.33% and 93.36%,respectively,from two samples.237,866 transcripts and 191,370 genes were constructed,with an average length of 1,103 bp and 1,298 bp respectively.All the assembled gene sequences were compared with Nr database,Nt database,Pfam,KOG/COG,Swiss-Prot,GO and KEGG database.153,895(80.41%)genes were annotated.In this experiment,we obtained 23,424 differentially expressed genes,of which 12,558 genes were up-regulated and 10,866 genes were downregulated.4.Analyze the expression pattern of differentially expressed genes and explore the molecular mechanism of Verbena bonariensis on heavy metal stress.Through the study of Cd stress onVerbena bonariensis photosynthetic effect,chelating agent changes and secondary metabolites changes,draw the conclusion: the effects of Cd stress Verbena bonariensis photosynthesis process in light absorption,electron transport and carbon assimilation efficiency;Verbena bonariensis by increasing in PC,organic acids and amino acids,and Cd ions the interaction of the chelation,avoid direct contact with Cd ions and organelles,thereby reducing the toxicity of Cd;through the synthesis of secondary metabolites,reducing Cd ion peroxidation,thereby enhancing the Verbena bonariensis Cd tolerance.5.The expression of Cd related differentially expressed genes in the KEGG pathway was studied by qRT-PCR method,and the credibility of RNA-seq data was verified.To sum up,this study provides a new strategy for further study of Cd tolerance and functional genomics,and is significant for the research and application of Verbena plants for remediation of heavy metal pollution.