Transcriptome analysis of Idesia polycarpa Maxim.var vestita Diels flowers during sex differentiation

摘要

Idesia polycarpa Maxim.var vestita Diels.is a dioecious tree species native to eastern Asia.There are diffi culties associated with distinguishing the sex of the plant at the seedling stage.In order to explore the mechanism of sex diff erentiation in fl ower development,we conducted the transcriptome profi les of male and female fl owers at early,metaphase and late developmental stages.Approximately 123,335 unigenes with a total length of 83,996 Mb and an average length of 168 bp were assembled.The unigenes were blasted into Nr,Nt,Pfam,KOG/COG,Swiss-prot,KEGG,GO databases.Homology analysis demonstrated that I.polycarpa and black cottonwood had the highest homology with the alignment of 92,871 sequences.This study identifi ed 80 groups of transcription factor families with a total of 1475 unigenes,mainly including MYB,WRKY,AP2 and bHLH transcription factor families.KEGG pathway analysis showed that the expression of numerous plant hormones(cytokinin,gibberellin and ethylene)and fl avonoid biosynthesis pathway were diff erent at various stages of female and male fl ower development.In addition,a number of unigenes associated with fl owering were identifi ed which were key genes associated with photoperiodic,vernalization,thermosensory,gibberellin,and autonomic pathways.The results show that I.polycarpa fl oral organ development was in accordance with the ABCDE model,in which the down-regulation of the B gene family might aff ect stamen fertility in late stages of female fl ower development.qRTPCR experiments validated that the expression patterns of 15 unigenes were consistent with those in RNA-seq results.The results highlight a central role for plant sex identifi cation in seedling production and a sex-determining mechanism for dioecious plants.In addition,the transcriptome data provided a theoretical basis for I.polycarpa genetic diversity analysis and molecular-assisted breeding.