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Open Access Research article

Systemic resistance and lipoxygenase-related defence response induced in tomato by Pseudomonas putida strain BTP1

Adam Akram1, Marc Ongena2, Francéline Duby3, Jacques Dommes3 and Philippe Thonart1*

Author Affiliations

1 Wallon Centre for Industrial Biology, University of Liège, Belgium

2 Bioindustry Unit, Gembloux Agricultural University, Belgium

3 Laboratory of plant molecular biology and biotechnology, University of Liège, Belgium

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BMC Plant Biology 2008, 8:113  doi:10.1186/1471-2229-8-113

Published: 10 November 2008

Abstract

Background

Previous studies showed the ability of Pseudomonas putida strain BTP1 to promote induced systemic resistance (ISR) in different host plants. Since ISR is long-lasting and not conducive for development of resistance of the targeted pathogen, this phenomenon can take part of disease control strategies. However, in spite of the numerous examples of ISR induced by PGPR in plants, only a few biochemical studies have associated the protective effect with specific host metabolic changes.

Results

In this study, we showed the protective effect of this bacterium in tomato against Botrytis cinerea. Following treatment by P. putida BTP1, analyses of acid-hydrolyzed leaf extracts showed an accumulation of antifungal material after pathogen infection. The fungitoxic compounds thus mainly accumulate as conjugates from which active aglycones may be liberated through the activity of hydrolytic enzymes. These results suggest that strain BTP1 can elicit systemic phytoalexin accumulation in tomato as one defence mechanism. On another hand, we have shown that key enzymes of the lipoxygenase pathway are stimulated in plants treated with the bacteria as compared with control plants. Interestingly, this stimulation is observed only after pathogen challenge in agreement with the priming concept almost invariably associated with the ISR phenomenon.

Conclusion

Through the demonstration of phytoalexin accumulation and LOX pathway stimulation in tomato, this work provides new insights into the diversity of defence mechanisms that are inducible by non-pathogenic bacteria in the context of ISR.