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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. Molecular Plant-Microbe Interactions, 12, 951-959

Department of Microbiology, SLU (Swedish University of Agricultural Sciences), Uppsala, Sweden.
Molecular Plant-Microbe Interactions (Impact Factor: 4.46). 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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    • "Quantification of mRNA levels showed increases in both the drought responsive gene and the biotic stress pathway; this showed that P. polymyxa caused mild biotic stress. Those results indicated that genes and/or gene classes related to plant defenses against abiotic and biotic stress may be co-regulated (Timmusk and Wagner 1999). DCY84 T , which induced relative transcription levels of several abiotic stress responsive genes, also showed plant resistance to biotic stress conditions of Xanthomonas oryzae pv. "
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    ABSTRACT: Current agricultural production methods, for example the improper use of chemical fertilizers and pesticides, create many health and environmental problems. Use of plant growth-promoting bacteria (PGPB) for agricultural benefits is increasing worldwide and also appears to be a trend for the future. There is possibility to develop microbial inoculants for use in agricultural biotechnology, based on these beneficial plant-microbe interactions. For this study, ten bacterial strains were isolated from Yongin forest soil for which in vitro plant-growth promoting trait screenings, such as indole acetic acid (IAA) production, a phosphate solubilization test, and a siderophore production test were used to select two PGPB candidates. Arabidopsis thaliana plants were inoculated with Paenibacillus yonginensis DCY84(T) and Micrococcus yunnanensis PGPB7. Salt stress, drought stress and heavy metal (aluminum) stress challenges indicated that P. yonginensis DCY84(T)-inoculated plants were more resistant than control plants. AtRSA1, AtVQ9 and AtWRKY8 were used as the salinity responsive genes. The AtERD15, AtRAB18, and AtLT178 were selected to check A. thaliana responses to drought stress. Aluminum stress response was checked using AtAIP, AtALS3 and AtALMT1. The qRT-PCR results indicated that P. yonginensis DCY84(T) can promote plant tolerance against salt, drought, and aluminum stress. P. yonginensis DCY84(T) also showed positive results during in vitro compatibility testing and virulence assay against X. oryzae pv. oryzae Philippine race 6 (PXO99). Better germination rates and growth parameters were also recorded for the P. yonginensis DCY84(T) Chuchung cultivar rice seed which was grown on coastal soil collected from Suncheon. Based on these results, P. yonginensis DCY84(T) can be used as a promising PGPB isolate for crop improvement. Copyright © 2015 Elsevier GmbH. All rights reserved.
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    • "Besides the biofertilizers, phytostimulators, and biopesticides, there are other PGPRs that induce tolerance in plants to abiotic stress. For instance, Paenibacillus polymyxa , Achromobacter piechaudii, and Rhizobium tropici confer tolerance to drought stress in Arabidopsis, tomato (Solanum lycopersicum), and common bean (Phaseolus vulgaris), respectively, possibly by abscisic acid accumulation and degradation of reactive oxygen species and 1-aminocyclopropane-1-carboxylate (Timmusk and Wagner, 1999; Mayak et al., 2004b; Figueiredo et al., 2008; Yang et al., 2009). Achromobacter piechaudii and B. subtilis are also involved in salinity tolerance in plants (Mayak et al., 2004a; Zhang et al., 2008; Yang et al., 2009). "
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    • "For example, salt tolerance induced by Bacillus subtilus was shown to be the result of tissue specific modulation of the expression of the Arabidopsis Na + /K + transporter, HKT1 (Zhang et al., 2008). Similarly , drought resistance in Arabidopsis as a result of inoculation with P. polymyxa was related to strong upregulation of the host gene ERD15 (Timmusk and Wagner, 1999). "
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