A Study On The Tolerance Mechanism Of Vetiver Grass Under Cu Stress

Vetiveria zizanioides is a perennial herb of the genus vetiveria,which has strong ecological adaptability,resistance to adversity and the ability to reduce heavy metals and other pollutants.It is considered as a pioneer plant for ecological reconstruction and heavy metal pollution control in coal mines.Based on vetiver grass as the research object,through hydroponic experiment,to explore different Cu concentration on the growth of vetiver,the influence of the physiological and biochemical changes,and on this basis,from the level of transcription and protein group differences analysis and mining of vetiver gene and protein,so as to reveal the tolerance mechanism of vetiver grass under the stress of Cu,for the use of vetiver will provide a scientific basis for repairing the heavy metal pollution.One control(without Cu)and four treatment concentrations(40,60,120 and 150mg/L)were used to treat vetiver with Cu stress.Three biological replicates were set in each treatment.After 7 days of stress,various morphological,physiological and biochemical indexes were sampled for identification and analysis of transcription and protein levels.The main findings are as follows1.Effects of Cu Stress on the Growth and Physiological Characteristics of vetiver: After 7 days of stress,it was found that vetiver leaves turned yellow and lost green when Cu concentration was 150mg/L,plant height,total root length,total root volume and fresh weight were significantly higher than the control when Cu concentration was 60mg/L,total root surface area and mean root diameter first decreased and then increased with the increase of Cu concentration,other indexes first increased and then decreased with the increase of Cu concentration,and the lowest values of all indexes appeared at 150mg/L.The results indicated that low concentration of Cu could promote the growth of vetiver,and the growth was gradually inhibited with the increase of concentration.The photosynthetic pigment content and SOD activity in leaves were the highest when Cu was treated at 60mg/L,and the POD activity in leaves,POD and SOD activity in roots were the highest when Cu was treated at 120mg/L.When the concentration was 150mg/L,the Cu concentration in roots was the highest.In conclusion,vetiver can remove reactive oxygen by increasing antioxidant enzyme activities(SOD,POD,CAT,etc.),reduce oxidative damage to cells,and respond to the toxicity of Cu stress.In addition,the comprehensive analysis showed that the Cu concentration tolerance of vetiver grass ranged from 60mg/L to 120mg/L.2.Transcriptome analysis of vetiver under Cu stress: a total of 438,200,619(GB)of high-quality data were obtained in this study.A total of 355,865 transcripts were obtained with an average length of 369 bp,among which 69712 and 74,302 differentially annotated genes on GO and KEGG were identified,respectively.GO enrichment analysis showed that these genes were mainly involved in metabolic processes,cell physiological processes,localization,cell,catalytic activity and binding,while KEGG enrichment analysis showed that these genes were mainly involved in phenylpropanol biosynthesis,photosynthesis,starch and sucrose metabolism,plant hormone signal transduction,plant-pathogens interaction and other pathways.Found in these biological processes and pathways MYB,AUX/IAA,b HLH,b ZIP,ZIP,NAC,WRKY Gene family and ABA,ABF,Sn RK2,B-ARR,ETR,MYC2,JAZ,CCR,4CL,F5 H,AMY/amy A,INV,HK,TPS,PAL,PR1,RIN4,WRKY33 PR and HSP90 difference of signal transduction genes in response to Cu stress,osmotic regulation,ion transduction,functional protein and transcriptional regulation plays an important role.3.Under Cu stress of vetiver proteomics analysis: there're a total of 1174 species of vetiver grass significantly different protein concentration,the root of the communist party of China has 1261 kinds of significant enrichment,GO significantly enriched analysis shows that these differences mainly involved in the process of cell metabolism,protein metabolism,cell process,transport activity and organic matter,Oxidoreductase activity and other biological processes,KEGG significant enrichment analysis shows that these differences styrene acrylic pigment biosynthesis of protein,starch and sucrose metabolism and Cyanoamino acid metabolism.And pathways in styrene acrylic element compounds found 40 kinds of differences in protein expression(peroxidase cinnamyl alcohol dehydrogenase,phenylalanine ammonia solution enzyme,shikimic acid/quinic acid hydroxy cinnamoyl transferase,etc.)and18 kinds of starch and sucrose metabolism difference of protein expression(beta glucoside enzyme and amylase,sucrose synthetase,etc.)participate in the process of vetiver grass Cu stress response.4.Correlation analysis of the transcriptome and proteome of vetiver under Cu stress: 348,464 transcripts and 8422 proteins were identified,and 8422 proteins could be converted into transcripts.The correlation coefficient between transcription and protein expression was 81.4%,with an average value of 0.405.Overall,there was a significant positive correlation between transcripts and protein expression levels,and the number of enriched proteins and genes was the fourth largest,with a total of840.These different proteins and genes are mainly involved in the metabolism of monocarboxylic acid,biosynthesis of monocarboxylic acid,and starch metabolism in the GO enrichment concentration.KEGG pathway mainly involves metabolic pathways,biosynthesis of secondary metabolites,carbon metabolism and ribosomes.Like transcriptome analysis or proteomic analysis alone,pathways for differential gene and protein enrichment are mainly concentrated in secondary metabolic processes such as phenylpropanoid synthesis,starch and sucrose metabolism.In conclusion,a certain concentration range of Cu(60?120mg/L)can promote the growth of vetiver.When the concentration range is beyond this range,the growth of vetiver will be inhibited,and at the same time,the antioxidant enzyme system will be activated to protect against the toxicity of Cu stress.Through comprehensive studies at the gene level,a large number of metabolic pathways and related gene proteins of vetiver in response to Cu stress were screened.These results provide an important candidate gene resource for subsequent researches on the resistance mechanism of vetiver under Cu stress,and also lay a good foundation for the selection and breeding of heavy metal-tolerant varieties to promote ecological restoration and reconstruction of heavy metal pollution.