Composition And Analysis Of Secretory Proteins In Salivary Glands And Midgut Of Citrus Psylla,Diaphorina Citri Kuwayama

The Asian citrus psyllid,Diaphorina citri Kuwayama is the transmission vector of HuangLongBing(HLB),which is a devastating disease in the citrus industry.The process of transmission of HLB pathogen transmitted by D.citri needs the participation of some organs such as salivary gland and midgut of this insect pest.The pathogen enters the salivary gland and digestive tract and proliferates in the body of D.citri with its feeding,and then spreads the pathogen to the citrus when it feed on the citrus tree again.In this study,the composition of salivary gland and midgut secretory proteins of D.citri was studied by transcriptome sequencing and analysis,and their potential physiological functions were analyzed.1.By analyzing the transcriptome data of salivary glands and midgut of D.citri female and male adult,15603 differentially expressed genes were obtained.GO and KEGG analysis showed that the salivary gland and midgut genes of D.citri differed in neurotransmitter transport,glutathione metabolism,starch and sucrose metabolism,but they had the same functions in protein transport,protein hydrolysis,transmembrane transport,ion transport and peroxisome metabolism.The transcriptome data analysis showed that the salivary glands and midgut of D.citri needed vigorous metabolism and efficient protein synthesis and transport system.The result also indicated that there were male and female differences between salivary glands and midgut of D.citri.2.1566 genes encoding secretory proteins were identified by bioinformatics.The specific expression of these secretory proteins genes in different tissues was studied.The result showed that there were 478 genes up-regulated in male and female salivary glands relative to midgut.20 secretory proteins genes up-regulated in salivary glands relative to midgut were selected for verification,and the results were basically same with those in transcriptome.The expression of SSP1,SSP2,SSP4 and SSP7 in salivary gland was significantly higher than that in midgut respectively.3.Three genes,SSP2,SSP4 and SSP7,were selected for prokaryotic expression.Their full-length sequences which was 1182 bp,507 bp and 978 bp respectively were obtained by gene synthesis technology,and the vectors were constructed for prokaryotic expression.By SDS-PAGE and Western blot identification,the optimal expression conditions of SSP2,SSP4 and SSP7 proteins were found to be induced at 37? for 4 hours,at 15? for 16 hours and at 37? for 4 hours,respectively.Finally,the three secreted protein genes were successfully expressed,which laid a solid foundation for further protein purification and function research.In conclusion,the secretory protein genes of salivary gland and midgut of D.citri have obvious tissue differential expression.The results revealed firstly the composition of secretory proteins in salivary glands and midgut of D.citri,and provided an important theoretical basis for the future study of the mechanism of transmission of bacteria and interaction with host plants.