Transcriptome-based Discovery of AP2/ERF Transcription Factors Related to Terpene Trilactones Synthesis in Ginkgo biloba

Abstract

Ginkgo biloba is a unique tree in China with medicinally and phylogenetically important characteristics. Terpene trilactones (TTL) is a key active pharmaceutical ingredient in Ginkgo, so the content of TTL in Ginkgo has become one of the important indices for evaluating quality of the medicinal materials. By transcriptome sequencing on samples treated by chlormequat, ultraviolet (UV) and drought, totally 59820 contigs and 37564 unigenes were obtained. Furthermore, 18234 unigenes were annotated through COG, KEGG and GO analysis. There were 78 AP2/ERF transcription factors, 23 factors of up-regulation and 66 factors of down-regulation that were related with synthetic pathway of TTL in Ginkgo. Phylogenetic tree clustering analysis indicated that there were 42 AP2s could be clustered into ERF, DREB and RVA subfamilies. EMSA analysis demonstrated that GbERF13, GbERF25 and GbERF27 could bind with regulatory elements, such as E-box, in the upstream of GbMECPs promoter. Expression analysis showed that the expression level of GbERF25 was the highest in root, and GbERF25 and GbERF27 were expressed in relatively high transcription levels in leaf and other tissues. The results of qRT-PCR indicated that CCC treatment could significantly improve expression levels of ERF25 and ERF27, and UV and drought could induce transcription levels of ERF13 and ERF25, respectively. The results implied that ERF25 and ERF27 might involve in the induction and regulation of CCC treatment on synthesis of bilobalide in G. biloba. ERF13 might participate in the regulation of bilobalide synthesis induced by UV, and EFR25 might involve in the regulation of the synthesis induced by drought. During annual cycle of expression, the transcription levels of ERF13, ERF25 and ERF27 had significantly positive correlation with diterpene level with correlation coefficient 0.975. It implied that these transcription factors mainly acted on the MEP pathway that regulated synthesis of bilobalide. The aim of the research was to indicate the mechanism of environment or cultivation measure regulating target gene of TTL metabolic pathway by AP2/ERF, and establish metabolic network of AP2/ERF regulating TTL synthesis.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Treatment of Ginkgo biloba with Exogenous Sodium Selenite Affects Its Physiological Growth, Changes Its Phytohormones, and Synthesizes Its Terpene Lactones

“…The CYP450 enzyme is the first step in the oxidation reaction of levopimaradiene and ginkgolides [ 9 ]. In recent years, regarding WRKY , bZIP , bHLH, and the AP2 / ERF family, TFs have been continuously cloned, and they have been proven to have a key regulatory role in the biosynthesis of terpenoids [ 4 , 37 , 38 ]. DXR catalyzes DXP to generate MEP, which is an important rate limiting enzyme in the MEP pathway and an ideal target for regulating the MEP pathway [ 8 ].…”

Transcriptomic Analysis Reveals Regulatory Networks for Osmotic Water Stress and Rewatering Response in the Leaves of Ginkgo biloba

“…Flavonoids and terpene lactones can function in eliminating ROS, blocking oxidation, and preserving plant growth during abiotic stress [1,88]. In addition, ginkgo leaves are famous for containing valuable flavonoids and terpene lactones [89,90]. Thus, it is important to understand the expression of genes involved in the biosynthesis of flavonoids and lactones terpene under water stress and rewatering conditions.…”