Ethylene-Inducible AP2/ERF Transcription Factor Involved in the Capsaicinoid Biosynthesis in Capsicum.

Jinfen Wen,Kai Zhao,Haishan Zhu,Junheng Lv,Zuosen Li,Hongjian Wan,Hong Zhang,Ziran Wang,Minghua Deng,Jinlong Huo,Xiang Zhang

doi:10.3389/fpls.2022.832669

Abstract

Ethylene is very important in the process of plant development and regulates the biosynthesis of many secondary metabolites. In these regulatory mechanisms, transcription factors (TFs) that mediate ethylene signals play a very important role. Capsaicinoids (CAPs) are only synthesized and accumulated in Capsicum species, causing their fruit to have a special pungent taste, which can protect against attack from herbivores and pathogens. In this study, we identified the TF CcERF2, which is induced by ethylene, and demonstrated its regulatory effect on CAPs biosynthesis. Transcriptome sequencing analysis revealed that the expression patterns of CcERF2 and multiple genes associated with CAPs biosynthesis were basically the same. The spatiotemporal expression results showed CcERF2 was preferentially expressed in the placenta of the spicy fruit. Ethylene can induce the expression of CcERF2 and CAPs biosynthesis genes (CBGs). CcERF2 gene silencing and 1-methylcyclopropene (1-MCP) and pyrazinamide (PZA) treatments caused a decrease in expression of CBGs and a sharp decrease in content of CAPs. The results indicated that CcERF2 was indeed involved in the regulation of structural genes of the CAPs biosynthetic pathway.

Highlights

Peppers (Capsicum spp.) are important vegetables worldwide
Expression of CcERF2 and CAPs biosynthesis genes (CBGs) Is Consistent With CAPs Biosynthesis
Considering that ethephon significantly induced the expression of CcERF2, our results showed that CcERF2 was a key factor in ethylene-mediated biosynthesis of CAPs (Figure 6)

Summary

Introduction

Peppers (Capsicum spp.) are important vegetables worldwide. Pepper fruits are diverse in color, rich in nutrients, have a special pungency and aroma, and so are widely used as food additives (Ou et al, 2018). The pungency of pepper fruit is derived from capsaicinoids (CAPs), which are only biosynthesized in Capsicum plants (Iwai et al, 1979; Liu et al, 2019). The CAPs have the effect of curbing attack by herbivores and microorganisms. CAPs are widely used in many fields such as food, medicine, cosmetics, and agricultural pest control; CAPs are widely used in riot prevention, personal defense, and in the military and national defense (Lejeune et al, 2007; Tewksbury et al, 2008; Ludy et al, 2012).

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