Evaluation of the Pseudomonas mediterranea UFV potential to control bacterial diseases of tomato plants

Studies report the potential of Pseudomonas species as biological control agents. Given the limited availability of biological-based products to control bacterial diseases of tomato, the focus of this work was to generate information on the potential of P. mediterranea UFV (Pm UFV) and the compounds produced by this strain in controlling tomato diseases caused by bacteria. The content of chapter 1 includes in vivo trials conducted to evaluate the best conditions for the development of bacterial spot of tomato (BST) symptoms caused by Xanthomonas euvesicatoria pv. perforans (Xep), to evaluate the effect of the preventive application of Pm UFV cell suspension on the development of BST caused by Xep and to determine the pathogenicity of the Pm UFV on different commercial tomato cultivars and the experimental model Micro-Tom. Also, the presence of gene clusters coding for the biosynthesis of phytotoxins in the Pm UFV genome was bioinformatically predicted. All tomato cultivars tested exhibited BST symptoms when inoculated with Xep under the different environments tested, the temperature that best favored the development of BST symptoms was 25 °C, and the application of Pm UFV cell suspension to tomato leaves inhibited BST symptoms. Interrogation of the Pm UFV draft genome sequence unveiled gene clusters for the biosynthesis of several phytotoxins, reinforcing the notion that Pm UFV has a high phytopathogenic potential. In chapter 2, it is described in vitro experiments aimed to determine the culture medium and growth phase of the Pm UFV strain most favorable for obtaining cell-free filtrate (CFF) with antibacterial activity, to evaluate the in vitro inhibitory effect of Pm UFV CFF against bacterial strains virulent to tomato plants, to obtain acid precipitate and supernatant fractions (APF and ASF, respectively) with antimicrobial activity, and to detect peptides present in these fractions. Our findings indicated culture media 3 and 4 as promoting the synthesis of antimicrobial compounds by Pm UFV. Virulent isolates of Ralstonia solanacearum (Rs) were sensitive to the CFF prepared from Pm UFV cultures in medium 3, however, it exhibited phytotoxicity when applied to the soil at a 50X concentration. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry coupled to mass spectrometry (MALDI-TOF/MS) analysis indicated several peptides present in the APF and ASF obtained from Pm UFV cultures. In chapter 3, results are presented on the preparation of crude extracts from Pm UFV cultures using solvents of different polarity and assessing their growth inhibitory effect on virulent Xep and Rs strains. The crude extract in dichloromethane (Pm/dichloromethane) exhibited antimicrobial activity against Rs whereas the Pm/ethanol caused growth inhibition of both Xep and Rs. When applied to tomato plants, Pm/ethanol caused reduction of BST symptoms. Using gas chromatography coupled to mass spectrometry (GC/MS) and bioinformatics predictions, compounds (potentially) produced by Pm UFV and putatively involved in the antimicrobial activity were partially identified. Further in vivo studies are necessary to determine the real potential of APF, ASF, crude extracts and/or partially purified compounds obtained from Pm UFV cultures in the control of Xep or Rs. Keywords: Antibiosis. Biocontrol. Bacterial Spot of Tomato. Bacterial wilt. Solanum lycopersicum. Ralstonia solanacearum. Xanthomonas euvesicatoria pv. perforans.

Grantor dc:publisher

Universidade Federal de Viçosa

Year dc:date.issued

2025

Author dc:creator

• Sousa, Adryelle Anchieta

Advisor dc:contributor.advisor

• Pacheco, Jorge Luis Badel

Contributors dc:contributor

• Varejão, Eduardo Vinicius

• Tomate - Doenças e pragas - Controle biológico
• Pseudomonas mediterranea
• Bactérias fitopatogênicas

Statement dc:rights

• Acesso Aberto

Language dc:language.iso

eng

DOI

https://doi.org/10.47328/ufvbbt.2024.532

OAI identifier oai:identifier

oai:locus.ufv.br:123456789/34944