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Front. Microbiol. | doi: 10.3389/fmicb.2018.03088

Plant-growth promotion and biocontrol properties of three Streptomyces spp. isolates to control bacterial rice pathogens

  • 1Biocultivos S.A., Colombia
  • 2Departamento de Investigación y Desarrollo, Empresa Colombiana de Productos Veterinarios, VECOL S.A., Colombia
  • 3Instituto de Biotecnología, Universidad Nacional de Colombia, Colombia
  • 4Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Colombia
  • 5International Centre for Genetic Engineering and Biotechnology, Italy
  • 6International Centre for Genetic Engineering and Biotechnology, Italy
  • 7Batteriologia e Batteriologia delle Piante, Centro Internazionale di Ingegneria Genetica e Biotecnologie - ICGEB, Italy

Bacterial Panicle Blight caused by Burkholderia glumae is a major disease of rice, which has dramatically affected rice production around the world in the last years. In this study we describe the assessment of three Streptomyces isolates as biocontrol agents for B. glumae. Additionally, the presence of other plant-growth promoting abilities and their possible beneficial effects upon their inoculation on rice plants was evaluated as an ecological analysis for their future inoculation in rice crops. Two isolates (A20 and 5.1) inhibited growth of virulent B. glumae strains, as well as a wide range of bacterial and fungal species, while a third strain (7.1) showed only antifungal activity. In vitro tests demonstrated the ability of these strains to produce siderophores, Indoleacetic acid (IAA), extracellular enzymes and solubilizing phosphate. Greenhouse experiments with two rice cultivars indicated that Streptomyces A20 is able to colonize rice plants and promote plant growth in both cultivars. Furthermore, an egfp tagged mutant was generated and colonization experiments were performed, indicating that Streptomyces A20 –GFP was strongly associated with root hairs, which may be related to the plant growth promotion observed in the gnotobiotic experiments. In order to characterize the antimicrobial compounds produced by strain A20 bacteria, mass spectrometry analyses were performed. This technique indicated that A20 produced several antimicrobial compounds with sizes below 3 kDa and three of these molecules were identified as Streptotricins D, E and F. These findings indicate the potential of Streptomyces A20 as a biocontrol inoculant to protect rice plants against bacterial diseases.

Keywords: Streptomyces, Plant growth promotion (PGP), biological control, Burkholderia glumae, Streptothricins

Received: 31 Aug 2018; Accepted: 29 Nov 2018.

Edited by:

Dirk Tischler, Ruhr-Universität Bochum, Germany

Reviewed by:

Collin M. Timm, Applied Physics Laboratory, Johns Hopkins University, United States
Matouš Čihák, Contipro Inc., Czechia  

Copyright: © 2018 Suarez Moreno, Vinchira-Villarraga, Vergara-Morales, Castellanos, Ramos, Guarnaccia, Degrassi, Venturi and Moreno-Sarmiento. 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:
Dr. Zulma R. Suarez Moreno, Biocultivos S.A., Bogotá D.C., Colombia, zrsuarezm@gmail.com
Dr. Giuliano Degrassi, Batteriologia e Batteriologia delle Piante, Centro Internazionale di Ingegneria Genetica e Biotecnologie - ICGEB, Trieste, Italy, degrassi@icgeb.org