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Induction of Resistance to Verticillium dahliae in Arabidopsis thaliana by the Biocontrol Agent K-165 and Pathogenesis-Related Proteins Gene Expression

June 2005 , Volume 18 , Number  6
Pages  555 - 561

Sotirios E. Tjamos , 1 Emmanouil Flemetakis , 2 Epaminondas J. Paplomatas , 1 and Panagiotis Katinakis 2

Agricultural University of Athens, 1Laboratory of Plant Pathology and 2Laboratory of Molecular Biology, 11855 Athens, Greece

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Accepted 13 January 2005.

The biocontrol bacterium Paenibacillus alvei K165 has the ability to protect Arabidopsis thaliana against Verticillium dahliae. A direct antagonistic action of strain K165 against V. dahliae was ruled out, making it likely that K165-mediated protection results from induced systemic resistance (ISR) in the host. K165-mediated protection was tested in various Arabidopsis mutants and transgenic plants impaired in defense signaling pathways, including NahG (transgenic line degrading salicylic acid [SA]), etr1-1 (insensitive to ethylene), jar1-1 (insensitive to jasmonate), npr1-1 (non-expressing NPR1 protein), pad3-1 (phytoalexin deficient), pad4-1 (phytoalexin deficient), eds5/sid1 (enhanced disease susceptibility), and sid2 (SA-induction deficient). ISR was blocked in blocked in Arabidopsis mutants npr1-1, eds5/sid1, and sid2, indicating that components of the pathway from isochorismate and a functional NPR1 play a crucial role in the K165-mediated ISR. Furthermore, the concomitant activation and increased transient accumulation of the PR-1, PR-2, and PR-5 genes were observed in the treatment in which both the inducing bacterial strain and the challenging pathogen were present in the rhizosphere of the A. thaliana plants.

Additional keywords: vascular wilt , plant-growth-promoting rhizobacterium .

© 2005 The American Phytopathological Society