Inhibition of Seed Germination and Induction of Systemic Disease Resistance by Pseudomonas chlororaphis O6 Requires Phenazine Production Regulated by the Flobal Regulator, GacS

Document Type

Article

Publication Date

4-1-2007

Keywords

GacS/GacA two-component system, Induced systemic resistance, Inhibition of seed germination, Phenazine

Abstract

Seed coating by a phenazine-producing bacterium, Pseudomonas chlororaphis O6, induced dose-dependent inhibition of germination in wheat and barley seeds, but did not inhibit germination of rice or cucumber seeds. In wheat seedlings grown from inoculated seeds, phenazine production levels near the seed were higher than in the roots. Deletion of the gacS gene reduced transcription from the genes required for phenazine synthesis, the regulatory phzI gene and the biosynthetic phzA gene. The inhibition of seed germination and the induction of systemic disease resistance against a bacterial soft-rot pathogen, Erwinia carotovora subsp. carotovora, were impaired in the gacS and phzA mutants of P. chlororaphis O6. Culture filtrates of the gacS and phzA mutants of P. chlororaphis O6 did not inhibit seed germination of wheat, whereas that of the wild-type was inhibitory. Our results showed that the production of phenazines by P. chlororaphis O6 was correlated with reduced germination of barley and wheat seeds, and the level of systemic resistance in tobacco against E. carotovora. © The Korean Society for Microbiology and Biotechnology.

Journal Title

Journal of Microbiology and Biotechnology

Volume

17

Issue

4

First Page

586

Last Page

593

First Department

Biology

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