Transcriptome Analysis On Vector/Non-vector Aphids In Response To Plant Virus

Triticum aestivum L.is one of the largest food crops in the world,and pests and diseases are important factors affecting wheat yield.Schizaphis graminum,Sitobion avenae and Rhopalosiphum padi are important pests of wheat,and can cause significant losses by feeding or transmit viruses.Barley yellow dwarf virus(BYDV)(Luteoviridae: Luteovirus)and wheat dwarf virus(WDV)(Geminiviridae: Mastrevirus)are serious viral disease of wheats in China,which may cause serious losses.In farmland ecosystems,arthropod herbivores and pathogens have complex and specific interactions.Previous studies have shown that plant viruses can directly or via host plant indirectly,either favorably or unfavorably,affect insect herbivores.In order to analyze the response of vector/non-vector aphids to wheat virus at the transcriptional level,this study performed transcriptome sequencing on aphids fed on BYDV-/WDV-infected and healthy wheat plants,respectively.After the quality control of the transcriptome data,the assembly,function annotation and analysis were carried out.And we examined the differences in gene expression of wheat aphids in response to feeding on wheat plants infected with BYDV or WDV.We conducted GO and KEGG analyses and observed differentially expressed genes(DEGs)related to immune pathway,growth,development,and reproduction.And we conducted cloning of two differentially expressed genes involved in immune pathway.This study provides a theoretical basis for the study of the response mechanism of vectoe/non-vector insects to plant viruses and the control of wheat pests and viral diseases.The main results were as follows:1.The transcriptome sequencing results showed that the Clean Data of each sample was above 6 Gb.A total of 72,092 Unigenes were assembled from S.graminum;61,508 Unigenes were assembled from S.avenae;and 68,916 Unigenes were assembled from R.padi.The N50 was 1481,1679 and 1497,respectively,indicating that the assembly integrity was good.There were 21507,18665,and 22226 Unigene was successfully annotated by comparing to each of the database,respectively.2.The results of DEGs analysis showed that the number of DEGs in vector aphids was larger than that in non-vector,and the number of DEGs in aphids exposed to BYDV was higher than that exposed to WDV.The effect of wheat virus on vector aphids was greater than that on non-vector aphids.The effect of BYDV on wheat aphids is greater than that of WDV on wheat aphids.This may revealed that wheat plants impact larger on vector aphids than on non-vector aphids,and BYDV impact larger on aphids than WDV.3.For DEGs annotation,we identified and analyzed the DEGs related to immune,growth,development,reproduction and metabolism.All 24 genes showed the same expression pattern(upregulated or downregulated)for both RT-qPCR and RNA-Seq analyses.4.We cloned the STAT5B(signal transducer and activator of transcription 5B)involved in JAK-STAT pathway and CUL2(cullin 2)involved in Ubiquitin mediated proteolysis.Bioinformatics analysis and expression level verification of RpSTAT5 B and SaCUL were then carried out.To sum up,transcriptome sequencing was performed on three aphids after feeding on healthy,BYDV-infected and WDV-infected wheat.Unigene expression analysis showed that the number of differentially expressed genes(DEGs)in the vector aphids was larger than that in the non-vector aphids.Functional enrichment analysis showed that the DEGs related to immunity,growth and reproduction in vector aphids were larger than those in non-vector aphids,and the differentially expressed genes related to immune were up-regulated.We also cloned and analyzed the immune related gene RpSTAT5 B and SaCUL.