Transcriptome profiling of spike provides expression features of genes related to terpene biosynthesis in lavender

Danli Guo,Kaicheng Kang,Min Li,Xianzhong Huang,Pu Wang

doi:10.1038/s41598-020-63950-4

Abstract

Lavender (Lavandula angustifolia) is an important economic plant because of the value of its essential oil (EO). The Yili Valley in Xinjiang has become the largest lavender planting base in China. However, there is a lack of research on the gene expression regulation of EO biosynthesis and metabolism in local varieties. Here, de novo transcriptome analysis of inflorescence of three development stages from initial flower bud to flowering stage 50% from two lavender cultivars with contrasting EO production revealed the dynamics of 100,177 differentially expressed transcripts (DETs) in various stages of spike development within and across the cultivars. The lavender transcriptome contained 77 DETs with annotations related to terpenoid biosynthesis. The expression profiles of the 27 genes involved in the methylerythritol phosphate (MEP) pathway, 22 genes in the mevalonate (MVA) pathway, 28 genes related to monoterpene and sesquiterpene biosynthesis during inflorescence development were comprehensively characterized, and possible links between the expression changes of genes and contents of EO constituents were explored. The upregulated genes were mainly concentrated in the MEP pathway, while most genes in the MVA pathway were downregulated during flower development, and cultivars with a higher EO content presented higher expression of genes in the MEP pathway, indicating that EOs were chiefly produced through the MEP pathway. Additionally, MYB transcription factors constituted the largest number of transcripts in all samples, suggesting their potential roles in regulating EO biosynthesis. The sequences and transcriptional patterns of the transcripts will be helpful for understanding the molecular basis of lavender terpene biosynthesis.

Highlights

Lavender (Lavandula angustifolia) is an important economic plant because of the value of its essential oil (EO)
The MVA pathway intermediate products and enzymes are 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA), which is catalysed by HMG synthase (HMGS); MVA, which is catalysed by HMG reductase (HMGR), a key enzyme of this pathway[13]; mevalonate-5-phosphate (MVAP), which is catalysed by the MVA kinase (MK); mevalonate-5-pyrophosphate (MVAPP), which is catalysed by the phosphomevalonate kinase (PMK); and isopentenyl pyrophosphate (IPP), which is catalysed by the mevalonate 5-pyrophosphate decarboxylase (MVD)[14,15]
We have described in detail the expression profiles of genes during three development stages from initial flower bud to flowering stage 50% within and across the cultivars, so what was the correspondence between the expression pattern and EO production? It was clear that most genes in the methylerythritol phosphate (MEP) pathway were strongly upregulated at flowering stage 50%, while most genes in the MVA pathway were downregulated in two cultivars (Supplementary Table S4), so we assumed that genes in MEP pathway contribute more the EO production

Summary

Introduction

Lavender (Lavandula angustifolia) is an important economic plant because of the value of its essential oil (EO). The expression profiles of the 27 genes involved in the methylerythritol phosphate (MEP) pathway, 22 genes in the mevalonate (MVA) pathway, 28 genes related to monoterpene and sesquiterpene biosynthesis during inflorescence development were comprehensively characterized, and possible links between the expression changes of genes and contents of EO constituents were explored. EO components are synthesized by the condensation reaction of the universal isoprenoid precursor isopentenyl pyrophosphate (IPP) and its double-bond isomer dimethyl allyl pyrophosphate (DMAPP)[8,9] through the mevalonate (MVA) and the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, called the 1-deoxy-D-xylulose 5-phosphate (DXP) pathway[10,11,12]. Mono- and sesquiterpenes are synthesized by GPP and FPP, respectively, via a series of terpene synthases (TPSs)

Methods

Results

Discussion

Conclusion