ImprimatinC1, a novel plant immune-priming compound, functions as a partial agonist of salicylic acid

Yoshiteru Noutoshi,Yusuke Jikumaru,Yuji Kamiya,Ken Shirasu

doi:10.1038/srep00705

Yoshiteru Noutoshi, Yusuke Jikumaru + Show 2 more

Open Access

https://doi.org/10.1038/srep00705

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Abstract

Plant activators are agrochemicals that protect crops from pathogens. They confer durable resistance to a broad range of diseases by activating intrinsic immune mechanisms in plants. To obtain leads regarding useful compounds, we have screened a chemical library using an established method that allows selective identification of immune-priming compounds. Here, we report the characterisation of one of the isolated chemicals, imprimatinC1, and its structural derivative imprimatinC2. ImprimatinC1 functions as a weak analogue of salicylic acid (SA) and activates the expression of defence-related genes. However, it lacks antagonistic activity toward jasmonic acid. Structure-activity relationship analysis suggests that imprimatinC1 and C2 can be metabolised to 4-chlorobenzoic acid and 3,4-chlorobenzoic acid, respectively, to function in Arabidopsis. We also found that imprimatinC1 and C2 and their potential functional metabolites acted as partial agonists of SA. Thus, imprimatinC compounds could be useful tools for dissecting SA-dependent signal transduction pathways.

Highlights

Plant activators are agrochemicals that protect crops from pathogens
Structure-activity relationship analysis suggests that imprimatinC1 and C2 can be metabolised to 4-chlorobenzoic acid and 3,4-chlorobenzoic acid, respectively, to function in Arabidopsis
effector-triggered immunity (ETI) is a more rapid and stronger type of response than PAMP-triggered immunity (PTI), and it often results in the so-called hypersensitive response (HR), which consists of rapid induction of programmed death of infected cells that contain pathogens at the site of infection[1]

Summary

Introduction

Plant activators are agrochemicals that protect crops from pathogens. They confer durable resistance to a broad range of diseases by activating intrinsic immune mechanisms in plants. Applied SA can trigger defence responses, and it confers disease resistance against pathogens, including fungi, bacteria and viruses Such enhanced disease resistance due to chemical inducers, referred to as plant activators, provides an effective method of crop protection[5]. Benzothiadiazole (BTH) and 2,6-dichloroisonicotinic acid (INA) were developed as synthetic analogues of SA and BTH can be used in the field[7,8] In contrast to such functional SA analogues, which directly induce defence responses, probenazole increases the potential for disease resistance responses in plants[9]. This immune-priming compound was discovered accidentally 35 years ago, and it is commercially available for the purpose of protecting paddy field rice from blast fungus and bacterial leaf blight[10]. We characterised a novel immune-priming compound, imprimatinC1, which functions as a partial agonist of SA

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