(E)-Nerolidol is a volatile signal that induces defenses against insects and pathogens in tea plants

Shenglong Chen,Lei Bian,Zhaojun Xin,Xiaoming Cai,Liping Zhang,Zhaoqun Li,Zongmao Chen,Xin Li,Zongxiu Luo

doi:10.1038/s41438-020-0275-7

Shenglong Chen, Lei Bian + Show 7 more

Open Access

https://doi.org/10.1038/s41438-020-0275-7

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Abstract

Plants release large amounts of volatile organic compounds (VOCs) in response to attackers. Several VOCs can serve as volatile signals to elicit defense responses in undamaged tissues and neighboring plants, but many questions about the ecological functions of VOCs remain unanswered. Tea plants are impacted by two harmful invaders, the piercing herbivore Empoasca (Matsumurasca) onukii Matsuda and the pathogen Colletotrichum fructicola. To determine the VOC signals in tea, we confirmed CsOPR3 as a marker gene and set up a rapid screening method based on a 1.51 kb CsOPR3 promoter fused with a β-glucuronidase (GUS) reporter construct (OPR3p::GUS) in Arabidopsis. Using this screening system, a terpenoid volatile (E)-nerolidol was identified as a potent signal that elicits plant defenses. The early responses triggered by (E)-nerolidol included the activation of a mitogen-activated protein kinase and WRKY, an H2O2 burst, and the induction of jasmonic acid and abscisic acid signaling. The induced plants accumulated high levels of defense-related chemicals, which possessed broad-spectrum anti-herbivore or anti-pathogen properties, and ultimately triggered resistance against Empoasca onukii and Colletotrichum fructicola in tea. We propose that these findings can supply an environmentally friendly management strategy for controlling an insect pest and a disease of tea plants.

Highlights

Green plants are susceptible to pervasive attack by herbivorous insects and microbial pathogens during their life cycle
Direct defense mechanisms include the use of toxic metabolites such as phytoalexins and protease inhibitors, physical barriers such as callose and lignin, and other nonvolatile defense-related enzymes such as phenylalanine ammonia lyase (PAL) and polyphenol oxidases (PPOs) which are stored in specialized cells to be activated when plants are attacked by pathogens or herbivores[4]
The CsOPR3 protein accumulated in the wounded leaves and reached its maximum level 3 h after treatment after which its expression decreased until the increase in its levels disappeared at 24 h (Fig. 1a)

Summary

Introduction

Green plants are susceptible to pervasive attack by herbivorous insects and microbial pathogens during their life cycle. Direct defense mechanisms include the use of toxic metabolites such as phytoalexins and protease inhibitors, physical barriers such as callose and lignin, and other nonvolatile defense-related enzymes such as phenylalanine ammonia lyase (PAL) and polyphenol oxidases (PPOs) which are stored in specialized cells to be activated when plants are attacked by pathogens or herbivores[4]. To activate these different defenses, Chen et al Horticulture Research (2020)7:52 distinct defense pathways are involved in the response to insects and pathogens in plants. The SA and H2O2 pathways mainly induce resistance against biotrophic pathogens and most sucking/piercing insects, whereas the JA pathway mainly confers resistance against necrotrophic pathogens, several phloem-sap-sucking insects and chewing herbivores[8,9]

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