Effects Of Methyl Methane Sulfonate Treatment On Gene Expression Changes Of Paulownia Fortunei Infected By Paulownia Witches'broom

Paulownia Witches Broom(Pa WB)caused by phytoplasma infection of phloem of Paulownia is a fatal disease in Paulownia production.This infectious disease has the characteristics of high harmfulness,difficult cure and high lethality,which has brought serious economic losses to agricultural and forestry production.Transcriptionomic analysis provides a comprehensive understanding of plant transcriptional responses to changing environments.Time series transcriptome analysis can help clarify the sensitive period of response.Weighted Coexpression Network Analysis(WGCNA)is a particularly powerful method for identifying not only modules with high biological significance,but also genes with high connectivity or in modules,which are essentially hub genes.Therefore,digging genes closely related to the occurrence of Pa WB and analyzing the pathogenesis is an important content of Pa WB research.In this research,Pa WB-infected samples treated with20 mg L-1 and 60 mg L-1 methyl methylsulfonate(MMS)at different time points were selected.The process of Paulownia from susceptibility to recovery to illness to recovery to health was simulated.Simulated the process of paulownia from sensation? form recovery to health ? disease and gradual recovery.The llumina Hi Seq high-throughput sequencing technology was applied to perform transcriptome sequencing of Paulownia responded to phytoplasma infection to obtain complete transcriptome.Subsequently,the gene expression profiles of Paulownia responding to phytoplasma infection stress were comprehensively and systematically analyzed by means of bioinformatics.By comparing the differentially expressed gene profiles of different control groups,we studied the changes of gene expression in Paulownia fortunei infected by phytoplasma.Combined with weighted gene co-expression network analysis(WGCNA),we constructed the gene co-expression network of Paulownia fortunei for the first time,and then excavated the genes closely related to Pa WB.The main results are as follows:(1)Transcriptome analysis was performed on 13 samples including PF,PFI,PFI20-5,PFI 20-10,PFI 20-15,PFI 20-30,PFI 20R-10,PFI 20R-20,PFI 20R-30,PFI20R-40,PFI 60-5,PFI 60-10,PFI 60-20,and 13 samples(three biological repeats).The Clean Data of all samples reached 11.94 Gb and the base percentage of Q30 was 88.88% and above.Clean Reads and Paulownia genome were sequenced,and the efficiency ranged from 65.17% to 81.33%.Pearson's Correlation Coefficient r2 all above 0.8.(2)The trend of gene changes at different time points in MMS treatment was found.In Paulownia infected by phytoplasma,In the treatment stage,the genes of PFI20-10 and disease seedling were the least and the sensitivity was the weakest,while those of PFI 20-15 and PFI 20-30 were the most and the sensitivity was the strongest.PFI 60-10 and healthy seedlings have the most different genes and the highest sensitivity,while PFI 60-20 and healthy seedlings have the least different genes and the weakest sensitivity.The number of PFI 20-5 gene changed most during the 20 mg L-1MMS treatment.During the recovery stage,the number of genes did not change much.The number of PFI 60-20 gene changed most during the 60 mg L-1MMS treatment.(3)Screening of genes specifically related to the occurrence of Paulownia Witches Broom.57 genes related to the occurrence of Paulownia Witches Broom were identified by comparative analysis.GO entries include fungal defense response,lignin decomposition process,etc.Enriched KEGG metabolic pathways include plant hormone signal transduction pathway zeatin biosynthesis.Based on the Paulownia fortunei transcriptome,the co-expression network of paulownia genes was constructed by WGCNA,and three modules related to the occurrence of Pa WB were obtained.The genes in the modules were closely related to the morphological changes after phytoplasma infection.Visual analysis was performed on the three modules,and five core genes were obtained,which were:zeatin O-glucosyltransferase,cytokinin dehydrogenase,fructose-bisphosphate aldolase,glyceraldehyde-3-phosphate dehydrogenase,aquaporin TIP2,chlorophyll a-b binding protein 7,chlorophyll a-b binding protein CP26,chlorophyll a-b binding protein CP26.