Transcriptome Analysis of Paeonia lactiflora in Response to Alternaria tenuissima Infection
[Objective]Paeonia lactiflora(P.lactiflora)is prone to pathogen infection during its growth and development.Leaf red spot disease caused by the Alternaria tenuissima(A.tenuissima)seriously affects both the quality and yield of the plant.However,the disease resistance mechanism of P.lactiflora is not clear at present.This study aimed to explore the physiological changes and molecular response pathways of P.lactiflora in response to the infection of A.tenuissima by using physiological and transcriptomic approaches.[Method]Taking P.lactiflora Dafugui as the experimental material,the leaves of them at 12,24 and 96 h after A.tenuissima infection were taken respectively to determine the relevant physiological indexes and perform transcriptome sequencing analysis,used uninoculated leaves as the control.[Result]After pathogen inoculation,the activities of SOD,POD,CAT and PAL of the leaves of P.lactiflora increased,the content of soluble sugar,soluble protein and MDA increased,but the content of proline decreased.The differentially expressed genes(DEGs)in each stage were screened after 12,24 and 96 h of A.tenuissima infection.There were 5 045,5 961 and 2 748 DEGs up-regulated,and 4 284,5 665 and 3 536 DEGs were down-regulated in each stage.GO enrichment analysis showed that these DEGs were mainly enriched in some biosynthesis and metabolic processes,photosynthesis-related,signal transduction-related and rhythm-related items.KEGG enrichment analysis showed that these DEGs were mainly enriched in carbon metabolism,amino acid biosynthesis,plant-pathogen interaction,plant hormone signal transduction,MAPK signaling,and other pathways.A total of 53 DEGs were enriched in three disease resistance pathways(plant-pathogen interaction,MAPK signaling and plant hormone signal transduction pathways).These DEGs included 1 MPK6,2 PR1,4 MKK4/5,and 46 BAK1.Nine differentially expressed genes of P.lactiflora in response to A.tenuissima infection were selected for qRT-PCR analysis.The gene expression pattern was consistent with the transcriptome sequencing results,which confirmed the accuracy of RNA-seq.The transcription factor families analysis showed that the AP2/ERF-ERF,WRKY,bHLH and MYB-related transcription factor families were the key transcription factor families of P.lactiflora in response to A.tenuissima.[Conclusion]After A.tenuissima infected,the antioxidant capacity of P.lactiflora was increased by increasing the activities of SOD,POD,CAT,and PAL,to remove the large amount of reactive oxygen species produced by disease stress,maintaining cell water by increasing the content of soluble sugars and soluble proteins and reducing the content of proline.The continuous increase of MDA content indicated that the cell membrane structure of plants was destroyed.The BAK1,PR1,MKK4/5 and MPK6 genes played important roles in response to A.tenuissima infection.It was preliminarily speculated that PlERF20,PlERF1b,PlWRKY41,PlMYC4,and PlMYB62 were disease resistance related transcription factor in response to A.tenuissima infection.
国家科技期刊平台
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