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Front. Plant Sci. | doi: 10.3389/fpls.2019.01448

Dual Mode of the Saponin Aescin in Plant Protection: Antifungal Agent and Plant Defense Elicitor

 Lucie Trdá1*,  Martin Janda1, 2, 3, Denisa Macková1, 2, Romana Pospíchalová1,  Petre Dobrev4,  Lenka Burketová1 and  Pavel Matušinsky5, 6
  • 1Laboratory of Pathological Plant Physiology, Institute of Experimental Botany (ASCR), Czechia
  • 2Laboratory of Plant Biochemistry, Department of Biochemistry and Microbiology, University of Chemistry and Technology in Prague, Czechia
  • 3Institute of Genetics, Faculty of Biology, Ludwig-Maximilians-University Munich, Germany
  • 4Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany (ASCR), Czechia
  • 5Agricultural Research Institute Kromeriz, Czechia
  • 6Department of Botany, Faculty of Science, Palacký University in Olomouc, Czechia

Being natural plant antimicrobials, saponins have potential for use as biopesticides. Nevertheless, their activity in plant–pathogen interaction is poorly understood. We performed a comparative study of saponins’ antifungal activities on important crop pathogens based on their effective dose (EC50) values. Among those saponins tested, aescin showed itself to be the strongest antifungal agent. The antifungal effect of aescin could be reversed by ergosterol, thus suggesting that aescin interferes with fungal sterols. We tested the effect of aescin on plant–pathogen interaction in two different pathosystems: Brassica napus versus (fungus) Leptosphaeria maculans and Arabidopsis thaliana versus (bacterium) Pseudomonas syringae pv tomato DC3000 (Pst DC3000). We analyzed resistance assays, defense gene transcription, phytohormonal production, and reactive oxygen species production. Aescin activated B. napus defense through induction of the salicylic acid pathway and oxidative burst. This defense response led finally to highly efficient plant protection against L. maculans that was comparable to the effect of fungicides. Aescin also inhibited colonization of A. thaliana by Pst DC3000, the effect being based on active elicitation of SA-dependent immune mechanisms and without any direct antibacterial effect detected. Therefore, this study brings the first report on the ability of saponins to trigger plant immune responses. Taken together, aescin in addition to its antifungal properties activates plant immunity in two different plant species and provides SA-dependent resistance against both fungal and bacterial pathogens.

Keywords: Brassica napus, Leptosphaeria maculans, Salicylic Acid, fungicide, Pseudomonas syringae, Arabidopsis thaliana, EC50

Received: 16 Aug 2019; Accepted: 17 Oct 2019.

Copyright: © 2019 Trdá, Janda, Macková, Pospíchalová, Dobrev, Burketová and Matušinsky. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Lucie Trdá, Laboratory of Pathological Plant Physiology, Institute of Experimental Botany (ASCR), Prague, 165 02, Prague, Czechia, lucie.trda@gmail.com