Transcriptome Variation Analysis Of Polyploidy Camellia Reticulata

Camellia reticulata Lindl.,the second-class national protected plant,the key of "eight famous flowers" in Yunnan Province,the city flower of Kunming,is famous of high tree and big flower.Studies have shown that C.reticulata is a polyploid complex,diploid C.reticulata(2X)and C.pitardii were hybridied and polyploidized to form the tetraploid C.reticulata(4X),tetraploid C.reticulata(4X)and C.saluenensis were hybridied and polyploidized to form the hexaploid C.reticulata(6X).In this study,RNA-Seq technology was used to sequence and compare the transcriptomes between different ploidy C.reticulata and its parents,and to explore the variation of transcription in the hybridization of C.reticulata.The research results mainly include the following aspects:1.A total of 403 158 unigene were sequenced in five transcription groups,with an average length of 412.81 bp,N50 of 432 bp.By comparing with Nr and other database,177 846(44.11%)unigenes were annotated.The 91 769 unigenes were divided into 3 categories including 41 function terms by GO annotation;and the 103 941 unigenes were classified into 25 groups by COG annotation;KEGG analysis showed that there were 53 627 unigenes divided into 4branches,involving 280 metabolic pathways.A total of 55 322 CDSs were obtained with an average length of 647.95 bp and N50 of 738 bp.A total of 55 257 SSR-containing sequences were searched for 61 533 SSRs,with the frequency of 15.26% or 1/2.70 kb.The average length of SSRs is16 bp,which is mainly distributed in the shorter sequence range.Negative relation existed between the frequency and the lenth of SSR sequence;In addition,SSRs in shorter repeat motifs with longer length were predicted with higher polymorphism.2.A total of 1 817 DEGs were screened between C.reticulata(4X)and its parents(C.reticulata(2X)and C.pitardii),and 2 914 DEGs were screened between C.reticulata(6X)and its parents(C.reticulata(4X)and C.saluenensis).These differentially expressed genes were mainly related to the biological processes of material synthesis,signal transduction and stress response.In the synthesis and metabolic pathways of terpenoids and flavonoids,the up-regulated expression of DXS,HDS and CHS genes and down-regulated expression of DFR and LAR genes make the number of effective substances in polyploid increased.DEGs were mainly in non-additive expression,while parental preference expression was present,and there were few genes silencing and activation in the polyploid of C.reticulata.The silent gene participates in the nucleobase-containing compound metabolic process,and activates genes involved in the stress reaction biological processes.