Deep sequencing identifies miRNAs and their target genes involved in the biosynthesis of terpenoids in Cinnamomum camphora

Abstract

Cinnamomum camphora is a tree of considerable economic and industrial importance. Terpenoids derived from the leaf essential oil of C. camphora are considered valuable components in the cosmetic and pharmaceutical industries. However, the possible gene-regulatory roles of microRNAs in C. camphora terpenoid biosynthesis are poorly understood. Here, we profiled the microRNA population and their targets in C. camphora with small RNA sequencing and degradome sequencing technology. Three hundred sixty-four known microRNAs and 117 novel microRNAs were detected in the linalool and borneol chemotype leaves of C. camphora. Fourteen differentially expressed microRNAs were identified between the linalool (F_L) and borneol (L_L) chemotype libraries, including 9 upregulated and 5 downregulated microRNAs in the borneol chemotype relative to the linalool chemotype. Among 12 selected miRNAs, the expression profiles of 11 microRNAs were consistent with the results of small RNA sequencing, and the results were verified by stem-loop quantitative real-time PCR. Based on the degradome sequencing analysis of the combined leaf samples, 363 and 144 target unigenes were predicted for 43 conserved microRNA families and 15 novel microRNAs, respectively. Target identification analyses revealed that some of the microRNAs, including miR4995, miR5021 and miR6300, might be related to the regulation of terpenoid biosynthesis. The analysis of microRNAs and their target unigenes in C. camphora not only contributes to our understanding of the gene-regulatory roles in differential terpenoid accumulation in C. camphora but also provides valuable resources for essential oil-related bioengineering studies.