Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 13: 745 - 754. Published January 5, 2009.
Biological control of Phytophthora capsici root rot of pepper (Capsicum annuum) using Burkholderia cepacia and Trichoderma harzianum
*^EZZIYYANI Mohammed, *REQUENA Maria Emilia, **EGEA-GILABERT Catalina, **REQUENA Ana Maria and *CANDELA Maria Emilia
*Department of Plant Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, 30100 Espinardo (Murcia), Spain. mcandela@um.es; **Department of Science and Agrarian Technology. ETS Agronomic Engineering, Polytechnic University of Cartagena Paseo Alfonso XIII, 48. 30203 Cartagena, Spain.
^Corresponding author e–mail:ezzim@um.es
ABSTRACT
Objective: Study the antagonistic capacity of a combination of two compatible microorganisms, the bacterium Burkholderia cepacia and the fungus Trichoderma harzianum against the pathogen Phytophthora capsici, the causal agent of rot in pepper.
Methodology and results: Evaluation of the two antagonists against the pathogen and between themselves was carried out by dual in vitro interactions in several cultural media, at different pH and temperature conditions. Both antagonists affected the survival and development of the pathogen P. capsici, through a variety of mechanisms. B. cepacia showed a high degree of antibiosis while T harzianum showed greater competition for space and nutrients, and a tendency to mycoparasitism and enzyme lysis. Biomass production of the antagonists was optimised in an Oat-Vermiculite medium, which proved to be efficient, cheap and rapid. The optimal doses of the antagonists were 3.5×108 spores/ml for T. harzianum and 109 CFU/ml for B. cepacia in a pH range of 3.5 - 5.6 and temperature range of 23 - 30 °C. In vivo treatment with the combination of B. cepacia + T. harzianum reduced the incidence of wilt caused by the pathogen P. capsici on pepper by up to 71%.
Conclusion and application of findings: One of the reasons for the success obtained is that we have obtained total compatibility between the two antagonists used, which belong to different genera with a wide antifungal spectrum. The use of such antagonistic microorganisms in biological control of plant pathogens provides an alternative to chemical products such as methyl bromide (MB) whose use is prohibited by the Montreal protocol, due to its environmentally harmful effects, especially thinning of the ozone layer.
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