Antibacterial Activity of Essential Oils and Trametes versicolor Extract against Clavibacter michiganensis subsp. michiganensis and Ralstonia solanacearum for Seed Treatment and Development of a Rapid In Vivo Assay.

Laura Orzali,Nicoletta Pucci,Stefania Loreti,Valeria Scala,Maria Teresa Valente

doi:10.3390/antibiotics9090628

Laura Orzali, Nicoletta Pucci + Show 3 more

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https://doi.org/10.3390/antibiotics9090628

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Journal: Antibiotics	Publication Date: Sep 21, 2020
Citations: 17	License type: CC BY 4.0

Affiliation: Institute for Sustainable Plant Protection

Abstract

Clavibacter michiganensis subsp. michiganensis (Smith) Davis et al. (Cmm) and Ralstonia solanacearum Yabuuchi et al. (Smith) (Rs) are important seed-borne bacterial pathogens of tomato (Solanum lycopersicum) listed as A2 pests in the EPPO (European and Mediterranean Plant Protection Organization) region. At present, there are few strategies to control these pathogens, and seed control with eco-compatible approaches is widely encouraged. In this work, the essential oils (EOs) of oregano (Origanum vulgare), garlic (Allium sativum), basil (Ocimum basilicum), cinnamon (Cinnamomum zeylanicum), clove buds (Syzygium aromaticum), thyme (Thymus vulgaris), and Trametes versicolor extract (Tve) were tested in vitro for their antimicrobial activity against Cmm and Rs (broth microdilution method). The tested EOs and the Tve extract caused a significant inhibition of bacterial growth, with very promising MBC (minimum bactericidal concentration) and MIC90 (minimum inhibitory concentration causing a 90% growth inhibition) values. Moreover, an in vivo germination test showed no major reduction in seed germination when the substances were applied as seed treatment. A rapid molecular screening method has been developed, through real-time PCR, for the specific quantification of Cmm in the presence of a vegetable matrix to test in vivo the antimicrobial efficacy of oregano and cinnamon oil on seed treatment without resorting to whole plant essays, which are time- and space-consuming.

Highlights

Clavibacter michiganensis subsp. michiganensis (Smith) Davis, Gillaspies, Vidaver & Harris (Cmm) and Ralstonia solanacearum (Smith) Yabuuchi et al (Rs) are important bacterial pathogens of tomato (Solanum lycopersicum L.), able to cause economic losses worldwide
A different antibacterial property of the analysed compounds was observed in this study
Rs are the causal agents of very devastating diseases

Summary

Introduction

Clavibacter michiganensis subsp. michiganensis (Smith) Davis, Gillaspies, Vidaver & Harris (Cmm) and Ralstonia solanacearum (Smith) Yabuuchi et al (Rs) are important bacterial pathogens of tomato (Solanum lycopersicum L.), able to cause economic losses worldwide. Michiganensis (Smith) Davis, Gillaspies, Vidaver & Harris (Cmm) and Ralstonia solanacearum (Smith) Yabuuchi et al (Rs) are important bacterial pathogens of tomato (Solanum lycopersicum L.), able to cause economic losses worldwide. The disease symptoms observed in plants infected by Cmm are wilt, yellow-brown vascular discoloration, cankers on stems, and petioles and lesions on fruit [2]. Cmm is transmitted to flowers and settles internally in developing seeds through vascular tissues [2], and externally through tomato fruit lesions [3]; it may contaminate the outside of the seed coat [4]. Infected young plants or asymptomatic infections during late stages of plant development, resulting in the production of contaminated seeds, are considered important for disease spread [7,8,9]. Prevention, based on seed testing and maintaining pathogen-free seeds and transplants, is currently the most appropriate approach for disease control, and cultural practices such as eradication of infected plants and disinfestation of materials are recommended [2,7,10]

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