Profiling of Widely Targeted Metabolomics for the Identification of Secondary Metabolites in Heartwood and Sapwood of the Red-Heart Chinese Fir (Cunninghamia Lanceolata)

Sen Cao,Yun Li,Huiquan Zheng,Zijie Zhang,Yuhan Sun

doi:10.3390/f11080897

Abstract

The chemical composition of secondary metabolites is important for the quality control of wood products. In this study, the widely targeted metabolomics approach was used to analyze the metabolic profiles of heartwood and sapwood in the red-heart Chinese fir (Cunninghamia lanceolata), with an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry system. A total of 224 secondary metabolites were detected in the heartwood and sapwood, and of these, flavonoids and phenolic acids accounted for 36% and 26% of the components, respectively. The main pathways appeared to be differentially activated, including those for the biosynthesis of phenylpropanoids and flavonoids. Moreover, we observed highly significant accumulation of naringenin chalcone, dihydrokaempferol, pinocembrin, hesperetin, and other important secondary metabolites in the flavonoid biosynthesis pathway. Our results provide insight into the flavonoid pathway associated with wood color formation in Chinese fir that will be useful for further breeding programs.

Highlights

The xylem of most woody plants can be divided into three parts: lighter sapwood (SW) on the periphery, darker heartwood (HW) on the inside, and the transition zone (TZ) at the color junction
A total of 224 secondary metabolites were covered in our assay (HW and SW; Figure 1A), including 80 flavonoids, 58 phenolic acids, 14 alkaloids, 9 lignans and coumarins, 7 tannins, 4 terpenoids, and 52 others (Figure 1B)
We identified the flavonoids in the HW of the red-heart Chinese fir, determined which substances differed from those in the SW, and more importantly, revealed the highly significant accumulation of naringenin chalcone, dihydrokaempferol, pinocembrin, hesperetin, and other important secondary metabolites in the flavonoid biosynthesis pathway

Summary

Introduction

The xylem of most woody plants can be divided into three parts: lighter sapwood (SW) on the periphery, darker heartwood (HW) on the inside, and the transition zone (TZ) at the color junction. HW contributes most to the value of the wood, and in most cases, it has a deep color that is likely associated with secondary metabolites. SW is often referred to as living tissue (5–25% of the components) and HW is mostly considered dead cells. The associated regulatory genes for metabolite production have been difficult to clarify in these tissues, in HW. Some tree species have a TZ that produces secondary metabolites on a temporary basis, and includes live parenchyma cells; it is generally believed that this metabolic activity peaks rapidly in the TZ and produces a large number of secondary metabolites that accumulate in the HW [1]. Given the value of HW, some studies have focused on its color. Miyamoto et al [2]

Methods

Results

Discussion

Conclusion