De Novo Transcriptome Sequencing of Ilex cornuta and Analysis of Genes Involved in Triterpenoid Biosynthesis

Ilex cornuta is a highly valuable medicinal plant rich in triterpenoids and flavonoids. Although many terpene medicinal ingredients have been isolated and identified from I. cornuta, genomic resources for investigating the biosynthesis of these components are lacking. Therefore, in this paper, we executed transcriptome sequencing in leaves, fruit and roots of I. cornuta which obtained 124,003 unigenes with an average length of 661 bp by de novo assembly. A total of 81,691 (65.9%) unigenes were functionally annotated through the Gene Ontology and Cluster of Orthologous Groups databases, and pathway analysis was performed by the Kyoto Encyclopedia of Gene and Genomes to understand the biological functions of genes. A total of 8966 differentially expressed genes were identified after comparing three organs. The qRT-PCR analysis found that the expression level of seven unigenes in roots was visibly higher than that in other organs. The HPLC results also indicated that triterpenoid (Total ursolic acids and oleanolic acids) was the highest in roots among the three organs. This study provides the first public transcriptome sequencing of I. cornuta, and offers a theoretical basis for molecular mechanism research on the triterpenoid biosynthesis. (C) 2019 Friends Science Publishers