Transcriptomic Analysis Of Differentially Expressed Genes In Sugarcane In Response To Yellow Leaf Virus Infection

Sugar cane is one of the world's important sugar and renewable energy crops.Due to its long growing season,it is easily infected with various diseases.Sugarcane yellow leaf disease?SCYLD?is caused by sugarcane yellow leaf virus?SCYLV?which is one of the main diseases affecting sugarcane crops with an incidence ranging from 10% to 100%.It can cause a reduction of 20%-60% yield of sugar cane.This study explored the differentially expressed genes?DEGs?associated with infection by transcriptome analysis of disease-resistant and susceptible sugarcane varieties.The result of this study can help to analyze the resistance mechanism of sugarcane for yellow leaf virus infection,it also laid a foundation for molecular marker-assisted breeding and genetic improvement of sugarcane against yellow leaf disease.The main results and conclusions are as follows:1.In this experiment,Melanaphis sacchari?Z?was used as a transmission vector,and both the resisitant variety ROC24 and the susceptible variety CP72-1210 were taken as test materials.The artificial inoculation was applied to inoculate sugarcane plants with SCYLV,and transcriptome sequencing was performed.Analysis of the transcriptome data revealed that 112788 and 106303 Unigenes were obtained respectively in the ROC24 and CP72-1210 transcriptome.Based on RNASeq analysis,we selected 938 DEGs in ROC24 data,of which 522 genes were up-regulated,and 416 were down-regulated.1980 DEGs were identified in CP72-1210 transcriptome data,of which the number of genes up-regulated was 1365 vs 615 genes down-regulated.2.Enrichment of DEGs into GO data revealed that the most annotated functions between the two transcriptome data were similar.Genes with binding and catalytic activity were most observed in the Molecular Functions clustor.Genes with the cell and cell part function in the cell components,and those with the metabolic process in the biological process were mroe than the others.155 and 79 KEGG metabolic pathways were identified respectively in the CP72-1210 and ROC24 transcriptome data.Further selection revealed four pathways related to disease resistance,namely the intecaction of plant-pathogen,plant hormone signal transduction,MAPK signaling pathway-plant and protein processing in endoplasmic reticulum.3.Aligning the transcriptome data of ROC24 and CP72-1210.17 disease resistance-related genes were identified in the ROC24 transcriptomes,including 1 protein kinase?CPK?,1 heat shock protein 90?HSP90?,5 heat shock protein 20?HSP20?,5 transcriptional regulators?WRKY?,and 5 disease-related non-expression?NPR1?genes.The expression level of WRKY decreased,and those of HSP90,HSP20 and NPR1 increased.CPK induces cell death by hypersensitivity reaction.HSP20 and HSP90 function in degradation process of viral proteins,WRKY induces plant defense by regulating defense-related genes,NPR1 regulates salicylic acid synthesis to enhance plant resistance.Meanwhile,we identified 2 susceptible genes in the CP72-1210 transcriptome,including 1 heat shock protein 20 and 1 transcription factor?MYC2?.The genes WRKY,HSP90,HSP20 and NPR1 genes did not expressed in comparision with that of ROC24,but the expression levels of one HSP20 and MYC2 genes decreased.MYC2 regulates the synthesis of jasmonic acid to weaken plant resistance.These results demonstrated that WRKY,CPK,HSP90,NPR1,HSP20 and MYC2 were key genes in sugarcane plants to develop resistance.4.Differential expression analysis of transcription factors revealed that a total of 116 genes in 21 transcription factor families were significantly expressed,and the most differentially expressed genes were in the WRKY transcription factor family.It was found that the three WRKY genes related to resistance in sugarcane plants are the same in sequences with the ZEAMMB73₂88216 genes in the maize database5.qRT-PCR was performed to verify the expression of the selected disease resistance-related genes above.The results of qRT-PCR showed that the expression levels of the 14 genes were consistent with those of the transcriptomes data,including 1 protein kinase?CPK?,1 heat shock protein 90?HSP90?,5 heat shock protein 20?HSP20?,4 transcription factors?WRKY?and 3 disease-related gene non-expression?NPR1?genes.In summary,this genes mainly enhance or attenuate plant resistance by regulating the expression of defense-related genes,affecting the production of plant disease resistance signals,and inhibiting the synthesis and transmission of viruses.