Transcriptome sequencing and comparative analysis between male and female floral buds of the persimmon (Diospyros kaki Thunb.)

Abstract

Although the OGI/MeGI system was reported to be essential in the sex determination of persimmons (Diospyros kaki Thunb.), the detailed regulatory mechanism of sex differentiation requires further investigation. In this study, RNA sequencing and comparative analysis between male and female floral buds collected from the same D. kaki ‘Zenjimaru’ tree were conducted to gain insight into gene expression profiles. In total, 1228 genes were differentially expressed between male and female floral buds. Based on gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and BLAST analysis, 25 differentially expressed genes involved functionally in phytohormone biosynthesis and signaling transduction, development of floral organs, transcription regulation, programmed cell death (PCD), and other processes were identified as crucial in the regulation of sex differentiation. Among the 25 genes, 15 were upregulated in male floral buds compared with female floral buds, whereas the other 10 were downregulated. Subsequently, the expression patterns of six crucial genes homologous to MeGI, GA20OX2, ACO, IAA32, beta-amyrin 28-oxidase-like, and HEC1 were determined in male and female floral buds during development with the use of real-time quantitative PCR. The results revealed that the genes homologous to IAA32, beta-amyrin 28-oxidase-like, and HEC1 showed male promoting effects from early June to the following late March. The gene homologous to GA20OX2 may stimulate the development of male floral buds in April. In contrast, the genes homologous to MeGI and ACO showed female promoting effects from early April to early May. The transcriptome datas provide comprehensive gene profiles for sex differentiation in D. kaki, as well as new directions and information for further studies in this field.