Study On Molecular Mechanism Of The Parasitic Interaction Between Smicronyx And Dodder

Smicronyx is a kind of parasitic insects,which mainly parasitize in dodder(Cuscuta).The molecular mechanism of the interaction between Smicronyx and Cuscuta remain largely unknown.When parasitized by Smicronyx,the stem of Cuscuta usually forms an entarged structure called gall.In order to investigate the formation mechanism of the gall,the life history of Smicronyx parasitizing Cuscuta was observed carefully,and the change of relevant phytohormones were compared between gall and stem by high performance liquid chromatography.Further,the differentially expressed transcript of them were analyzed by the transcriptome sequencing.We confirmed the differentially expressed genes expression pattern by qRT-PCR.The main results are showed as follows:1.Through the observation of life history of Smicronyx,it was found to belong to eggs-larva-pupa parasitic insect.2.Through mensuration of Auxin,Cytokinin(CTK),Jasmonic acid(JA)and Salicylic acid(SA)of gall and adjacent stem which is formed during Smicronyx parasitic Cuscuta by HPLC,the contents of Auxin,JA and CTK in Cuscuta gall have found to be higher than in stem.At the same time,SA was not detected in Cuscuta gall.It suggested that the Smicronyx parasitic Cuscuta stem can cause the change of content of phytohormone in it.3.By the Illumina sequencing of Cuscuta gall and stem transcriptome,there are 184,322 transcripts were found by Trinity assembling,in which there are 27,925 differentially expressed transcripts,and 9,925 differentially expressed transcripts have functional annotation.4.There are 76 Auxin,36 CTK,48 JA and 53 SA relevant transcripts been annotated through the alignment between phytohormone differentially expressed gene and Uniport?Gene Ontology database.After that,relevant transcripts were analyzed to find the possible function in the genome by using KEGG database.Furthermore,differentially expressed genes were validated by qRT-PCR analysis.The result of it were in accordance with the results of transcriptome analysis,indicating that JA,SA,Auxin and CTK might participate in controlling the formation of Cuscuta gall.These results have laid a solid foundation for further research of the molecular mechanisms of the interaction between Smicronyx and Cuscuta.