Transcriptome Sequencing and Analysis of Genes Related to Sucrose Metabolism and Transporter of Paeonia ostii Seed with Sucrose Treatment

Tree peony (Paeonia ostii) is an important ornamental plant with high oil and medical values and is widely distributed in China. In order to explore the effects of sucrose treatment on the growth of the P. ostii seeds and identify key genes involved in sucrose metabolism and transport during the early development of the P. ostii seeds, the comparative transcriptome sequencing of the P. ostii seed coats and endosperms at 50 days after flowering (DAF) with and without sucrose supply were conducted using Illumina HiSeq platform. A total of 97,976 unigenes were obtained and annotated with seven public function protein databases. There were 22,779, 22,632, 16,700, and 36,233 differentially expressed genes (DEGs) identified in the four comparisons, respectively. A total of 77 DEGs associated with the sucrose metabolism and transporter were identified in this study. Among them, sucrose transporter protein (SUT) and sweet sugar transporter (SWEET) were predicted to participate in sucrose transport from seed coat to embryo, and invertase (INV) was identified to be involved in sucrose degradation. In addition, sucrose synthase (SUS) and sucrose phosphate synthase (SPS) related to sucrose synthesis were highly expressed in seeds with sucrose supply. Finally, nine differentially expressed genes were selected randomly to analyze their expression levels using qRT-PCR, which were consistent with the transcriptome sequencing results. Above all, these results and analyses provide valuable gene resources and directions for further studying the effects of sucrose supply on the molecular mechanism of the sucrose metabolism and transporter during the development of P. ostii seeds.