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Study On Effects And Its Mechanism Of Bemisia Tabaci Transmittting Cucurbit Chlorotic Yellows Virus On Host

Posted on:2022-06-16Degree:MasterType:Thesis
Country:ChinaCandidate:B Z ShiFull Text:PDF
GTID:2543306317485044Subject:Resource utilization and plant protection
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Bemisia tabaci,is the only agricultural pest known as a superpest,and is also considered a supervector of the virus,widely distributed in tropical and subtropical regions.Bemisia tabaci is a complex population considering of at least 44 species.It can harmful to host plants,including feeding directly on leaf juice,producing honey dew,causing coal stain and spreading plant virus.Among the more than 400 plant viruses transmitted by Bemisia tabaci,Cucurbit chlorotic yellows virus(CCYV)is a newly reported virulent virus,which causes chlorosis of leaves and leaves with green veins after infection.Bemisia tabaci is the only vector of CCYV,and the occurrence of Bemisia tabaci is positively correlated with the incidence of CCYV.Previous studies in our laboratory have shown that CCYV affects the feeding behavior and development status of Bemisia tabaci.By comparing the physiological,biochemical and transcriptome levels of host cucumbers before and after feeding on Bemisia tabaci and healthy Bemisia tabaci,this study aims to study the influence of Bemisia tabaci transmission on host plants and the physiological and molecular mechanism,so as to further reveal the interaction relationship and mechanism between Bemisia tabaci-CCYV-host.(1)Effects of Bemisia tabaci transmission of CCYV on physiological characteristics of host plants.The physiological effects of feeding time(1 d,3 d,5 d,7 d,9 d)on host plants of Bemisia tabaci and Bemisia tabaci were compared with cucumber.The results showed that the Superoxide Dismutase(SOD)activity of Bemisia tabaci treated with VQ was significantly higher than that of HQ and CK on the 7th and 9th day under the feeding conditions of healthy Bemisia tabaci(HQ)and poisonous Bemisia tabaci(VQ),but there was no significant difference between CK and HQ groups.At the first day,the Peroxidase(POD)activity of VQ and HQ treatment groups was significantly higher than that of CK,which was mainly due to the activity of cucumber Peroxidase activated by Bemisia tabaci feeding.On the 7th and 9th day,POD activity of VQ was significantly higher than that of HQ and CK.On the first day,the activity of Phenylalanine ammonia lyases(PAL)in cucumber treated by VQ and HQ increased significantly compared with that of CK.On the 7th and 9th day,the activity of PAL in VQ group was still significantly higher than that of CK.The physiological and biochemical changes of plants were induced by both healthy and poisonous B.tabaci feeding,but the physiological changes caused by poisonous B.tabaci feeding were more obvious and lasted longer.Compared with the HQ and CK groups,the chlorophyll content of VQ showed an obvious decreasing trend,while the difference between the HQ and CK groups was not significant,indicating that the chlorophyll content in plants would be reduced during the transmission of Bemisia tabaci carrying CCYV,thus affecting the photosynthesis of plants.(2)Effects of Bemisia tabaci transmission of CCYV on gene expression in host plantsThe cucumber leaves of healthy and infected Bemisia tabaci were collected at the 3rd and 7th day after feeding,and transcriptome sequencing was performed using the transcriptome sequencing technology of Illumina platform.The total of 117.73 GB of Clean Data were obtained by transcriptome analysis of 18 samples.Sequence alignment of Clean Reads from each sample and the specified reference genome was performed,and the alignment efficiency was between 93.00%and 96.33%.Based on the comparison results,982 new genes were discovered through alternative splicing prediction analysis and gene structure optimization analysis,and 625 of them were functional annotations.The differentially expressed genes were identified according to their expression levels in different samples,and their functional annotation and enrichment analysis were performed.The differentially expressed genes were screened out when FDR<0.05 and FC≥1.5.There were 580 differentially expressed genes at the 3rd day,303 up-regulated genes and 277 down-regulated genes.At the 7th day,there were 405 differentially expressed genes,151 up-regulated genes and 254 down-regulated genes.At the 3rd day,580 genes were differentially expressed,303 were up-regulated and 277 were down-regulated.At the 7th day,405 differentially expressed genes were up-regulated by 151 and down-regulated by 254.The number of differential genes decreased by 30.17%,the up-regulated genes decreased by 50.17%,and the down-regulated genes decreased by 8.3%compared with that at the 3rd day and the 7th day.These genes are involved in plant photosynthesis,plant-pathogen interaction,secondary metabolism,and plant signal transduction.In order to verify the accuracy of high-throughput sequencing results,we selected 10 genes for qRT-PCR validation analysis.The results of this study showed that the transmission of the virus through Bemisia tabaci would cause physiological and biochemical changes and gene expression changes of the host plants,and these changes can improve the ability of plant defense and adaptation to biological stress,which is also the theoretical basis of plant resistance breeding and green pest control.
Keywords/Search Tags:Bemisia tabaci, Cucurbit chlorotic yellows virus, virus-vector-host interaction, protective enzymes, photosynthetic characteristics, gene expression
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