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
Source: PubMed


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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    ABSTRACT: Plants have a series of fine mechanisms for responding to environmental changes, which has been established during evolution and experiments. These mechanisms are involved in many aspects of physiology, biochemistry, genetics and molecular biology. Alterations in the levels of key signalling metabolites or transcription factors could provide an explanation for how plant metabolism regulation is altered by exposure to various stresses. Plant defence response genes are transcriptionally activated by biotic, as well by different forms of abiotic stress, the induction of specific defence genes in the response against certain pathogens, are dependent on specific environmental conditions, suggesting the existence of a complex signaling network that allows the plant to recognize and protect itself against pathogens and environmental stress. A variety of signal transducers exist in plants, for better understanding let us discuss some of them like Ca2+, reactive oxygen species (ROS), abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA) and protein kinases involved in phosphorylation cascades. The main components of stress-induced signalling molecules are the cross-talk between the different signalling pathways allows plants to adjust their responses depending on the combination of stimuli. A deep understanding of the mechanisms that respond to stress and sustain stress resistance is required. Here presented an overview of several mechanisms that interact in the stress regulation in plant.
    Recent Advances in Plant Stress Physiology, 10/2015: chapter Plant Stress Regulation: pages 117-136; Daya Publishing House., ISBN: ISBN 978-81-7035
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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.
    Microbiological Research 01/2015; 172. DOI:10.1016/j.micres.2015.01.007 · 2.56 Impact Factor
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    • "To test whether an environmental organism (defined here as a bacterium that is not known to colonize or infect mammals) encodes a heme-binding NEAT domain, we chose to clone and purify an IsdC-like NEAT domain homologue from the nitrogen-fixing agricultural inoculant, P. polymyxa (protein4; Pp-IsdCN; Table S1). P. polymyxa is a known root-tip colonizer and symbiont of a wide range of crops, where it protects plants against bacterial pathogens, and against abiotic stress, and is found in the surrounding soil [55], [64], [65]. It is also proposed that by forming biofilms, P. polymyxa outcompetes pathogens for space and nutrients. "
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    ABSTRACT: Iron is essential for bacterial survival, being required for numerous biological processes. NEAr-iron Transporter (NEAT) domains have been studied in pathogenic Gram-positive bacteria to understand how their proteins obtain heme as an iron source during infection. While a 2002 study initially discovered and annotated the NEAT domain encoded by the genomes of several Gram-positive bacteria, there remains a scarcity of information regarding the conservation and distribution of NEAT domains throughout the bacterial kingdom, and whether these domains are restricted to pathogenic bacteria. This study aims to expand upon initial bioinformatics analysis of predicted NEAT domains, by exploring their evolution and conserved function. This information was used to identify new candidate domains in both pathogenic and nonpathogenic organisms. We also searched metagenomic datasets, specifically sequence from the Human Microbiome Project. Here, we report a comprehensive phylogenetic analysis of 343 NEAT domains, encoded by Gram-positive bacteria, mostly within the phylum Firmicutes, with the exception of Eggerthella sp. (Actinobacteria) and an unclassified Mollicutes bacterium (Tenericutes). No new NEAT sequences were identified in the HMP dataset. We detected specific groups of NEAT domains based on phylogeny of protein sequences, including a cluster of novel clostridial NEAT domains. We also identified environmental and soil organisms that encode putative NEAT proteins. Biochemical analysis of heme binding by a NEAT domain from a protein encoded by the soil-dwelling organism Paenibacillus polymyxa demonstrated that the domain is homologous in function to NEAT domains encoded by pathogenic bacteria. Together, this study provides the first global bioinformatics analysis and phylogenetic evidence that NEAT domains have a strong conservation of function, despite group-specific differences at the amino acid level. These findings will provide information useful for future projects concerning the structure and function of NEAT domains, particularly in pathogens where they have yet to be studied.
    PLoS ONE 08/2014; 9(8):e104794. DOI:10.1371/journal.pone.0104794 · 3.23 Impact Factor
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