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The Plant-Growth-Promoting Rhizobacterium Paenibacillus polymyxa Induces Changes in Arabidopsis thaliana Gene Expression: A Possible Connection Between Biotic and Abiotic Stress Responses

Department of Microbiology, SLU (Swedish University of Agricultural Sciences), Uppsala, Sweden.
Molecular Plant-Microbe Interactions (Impact Factor: 3.94). 12/1999; 12(11):951-9. DOI: 10.1094/MPMI.1999.12.11.951
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ABSTRACT

This paper addresses changes in plant gene expression induced by inoculation with plant-growth-promoting rhizobacteria (PGPR). A gnotobiotic system was established with Arabidopsis thaliana as model plant, and isolates of Paenibacillus polymyxa as PGPR. Subsequent challenge by either the pathogen Erwinia carotovora (biotic stress) or induction of drought (abiotic stress) indicated that inoculated plants were more resistant than control plants. With RNA differential display on parallel RNA preparations from P. polymyxa-treated or untreated plants, changes in gene expression were investigated. From a small number of candidate sequences obtained by this approach, one mRNA segment showed a strong inoculation-dependent increase in abundance. The corresponding gene was identified as ERD15, previously identified to be drought stress responsive. Quantification of mRNA levels of several stress-responsive genes indicated that P. polymyxa induced mild biotic stress. This suggests that genes and/or gene classes associated with plant defenses against abiotic and biotic stress may be co-regulated. Implications of the effects of PGPR on the induction of plant defense pathways are discussed.

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    • "Plants without the pre-treatment will die (middle). (Modified from: Timmusk and Wagner, 1999). 2. The other situation is stress acclimation: usually the exposure of plants to sublethal doses of a stress is referred to as acclimation. "
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