AaWRKY17, a positive regulator of artemisinin biosynthesis, is involved in resistance to Pseudomonas syringae in Artemisia annua

Tiantian Chen,Yongpeng Li,Kuanyu Wu-Zhang,Xiaolong Hao,Chen Wang,Lihui Xie,Wei Qin,Xinghao Yao,Xueqing Fu,Xin Yan,Bowen Peng,Kexuan Tang,Yaojie Zhang,Ling Li,Hang Liu

doi:10.1038/s41438-021-00652-6

Tiantian Chen, Yongpeng Li + Show 13 more

Open Access

https://doi.org/10.1038/s41438-021-00652-6

Copy DOI

Abstract

Artemisia annua, a traditional Chinese medicinal plant, remains the only plant source for artemisinin production, yet few genes have been identified to be involved in both the response to biotic stresses, such as pathogens, and artemisinin biosynthesis. Here, we isolated and identified the WRKY transcription factor (TF) AaWRKY17, which could significantly increase the artemisinin content and resistance to Pseudomonas syringae in A. annua. Yeast one-hybrid (Y1H), dual-luciferase (dual-LUC), and electrophoretic mobility shift assay (EMSA) results showed that AaWRKY17 directly bound to the W-box motifs in the promoter region of the artemisinin biosynthetic pathway gene amorpha-4,11-diene synthase (ADS) and promoted its expression. Real-time quantitative PCR (RT-qPCR) analysis revealed that the transcript levels of two defense marker genes, Pathogenesis-Related 5 (PR5) and NDR1/HIN1-LIKE 10 (NHL10), were greatly increased in AaWRKY17-overexpressing transgenic A. annua plants. Additionally, overexpression of AaWRKY17 in A. annua resulted in decreased susceptibility to P. syringae. These results indicated that AaWRKY17 acted as a positive regulator in response to P. syringae infection. Together, our findings demonstrated that the novel WRKY transcription factor AaWRKY17 could potentially be used in transgenic breeding to improve the content of artemisinin and pathogen tolerance in A. annua.

Highlights

Plants are exposed to various stresses from the environment during their lifecycle, including abiotic stresses such as drought and biotic stresses such as pathogens[1,2]
Real-time quantitative PCR (RT-qPCR) results of different tissues showed that Aannua01956S266050 exhibited the highest expression level in trichomes among the five candidate genes, which was consistent with the transcriptome data from different A. annua tissues (Fig. 2A and Supplementary Fig. S1)
Since artemisinin is only produced in trichomes of A. annua, we speculated that Aannua01956S266050 potentially participated in artemisinin biosynthesis

Summary

Introduction

Plants are exposed to various stresses from the environment during their lifecycle, including abiotic stresses such as drought and biotic stresses such as pathogens[1,2]. For survival and the continuation of the generation, plants have adopted many defense mechanisms against biotic and abiotic stresses[3]. Among the various biotic stresses, pathogens are considered major threats to plant growth, development, and yield. The WRKY family forms a transcriptional network that regulates the complex signaling network in the plant defense system against pathogen infection[7]. As one of the largest TF families in plants, WRKY proteins are identified by two highly conserved domains: the amino acid motif WRKYGQK at the N-terminus and a C2H2 or C2HC zinc-finger motif at the C-terminus.

Methods

Results

Conclusion