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Burkholderia phytofirmans PsJN induces long-term metabolic and transcriptional changes involved in Arabidopsis thaliana salt tolerance.

Pinedo I, Ledger T, Greve M, Poupin MJ - Front Plant Sci (2015)

Bottom Line: Among the general transcriptional effects of this bacterium, the expression pattern of important ion-homeostasis related genes was altered after short and long-term stress (Arabidopsis K(+) Transporter 1, High-Affinity K(+) Transporter 1, Sodium Hydrogen Exchanger 2, and Arabidopsis Salt Overly Sensitive 1).In all, the faster and stronger molecular changes induced by the inoculation suggest a PsJN-priming effect, which may explain the observed tolerance after short-term and sustained salt-stress in plants.This opens up new venues to study these relevant biological associations, as well as new approaches to a better understanding of the spatiotemporal mechanisms involved in stress tolerance in plants.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez Santiago, Chile.

ABSTRACT
Salinity is one of the major limitations for food production worldwide. Improvement of plant salt-stress tolerance using plant-growth promoting rhizobacteria (PGPR) has arisen as a promising strategy to help overcome this limitation. However, the molecular and biochemical mechanisms controlling PGPR/plant interactions under salt-stress remain unclear. The main objective of this study was to obtain new insights into the mechanisms underlying salt-stress tolerance enhancement in the salt-sensitive Arabidopsis thaliana Col-0 plants, when inoculated with the well-known PGPR strain Burkholderia phytofirmans PsJN. To tackle this, different life history traits, together with the spatiotemporal accumulation patterns for key metabolites and salt-stress related transcripts, were analyzed in inoculated plants under short and long-term salt-stress. Inoculated plants displayed faster recovery and increased tolerance after sustained salt-stress. PsJN treatment accelerated the accumulation of proline and transcription of genes related to abscisic acid signaling (Relative to Dessication, RD29A and RD29B), ROS scavenging (Ascorbate Peroxidase 2), and detoxification (Glyoxalase I 7), and down-regulated the expression of Lipoxygenase 2 (related to jasmonic acid biosynthesis). Among the general transcriptional effects of this bacterium, the expression pattern of important ion-homeostasis related genes was altered after short and long-term stress (Arabidopsis K(+) Transporter 1, High-Affinity K(+) Transporter 1, Sodium Hydrogen Exchanger 2, and Arabidopsis Salt Overly Sensitive 1). In all, the faster and stronger molecular changes induced by the inoculation suggest a PsJN-priming effect, which may explain the observed tolerance after short-term and sustained salt-stress in plants. This study provides novel information about possible mechanisms involved in salt-stress tolerance induced by PGPR in plants, showing that certain changes are maintained over time. This opens up new venues to study these relevant biological associations, as well as new approaches to a better understanding of the spatiotemporal mechanisms involved in stress tolerance in plants.

No MeSH data available.


Related in: MedlinePlus

Effects of Burkholderia phytofirmans PsJN on Arabidopsis thaliana growth in vitro. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 days after sowing (DAS) to Murashige Skoog (MS) with or without addition of salt (150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2). Data was collected 7 days after transplantation. (B) Graphic representation of rosette area (left) and fresh weight (right) of plants treated under the experimental conditions described before. Data are means ± 1 SE of at least 20 plants per treatment. Asterisks indicate significant differences between control and PsJN treatment (Two-way ANOVA, p < 0.05; Bonferroni test, ∗∗∗P < 0.01). Results are representative of two different experiments. White bars in photographs correspond to 2 cm.
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Figure 1: Effects of Burkholderia phytofirmans PsJN on Arabidopsis thaliana growth in vitro. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 days after sowing (DAS) to Murashige Skoog (MS) with or without addition of salt (150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2). Data was collected 7 days after transplantation. (B) Graphic representation of rosette area (left) and fresh weight (right) of plants treated under the experimental conditions described before. Data are means ± 1 SE of at least 20 plants per treatment. Asterisks indicate significant differences between control and PsJN treatment (Two-way ANOVA, p < 0.05; Bonferroni test, ∗∗∗P < 0.01). Results are representative of two different experiments. White bars in photographs correspond to 2 cm.

Mentions: To address for differences in growth of A. thaliana Col-0 plants exposed to salt-stress in vitro, seeds were sown in half strength Murashige and Skoog (1962) media (MS1/2) with or without inoculation of strain PsJN as described in the “Materials and Methods” section. At 11 DAS, plants were transferred to MS1/2 media containing different salt concentrations ranging from 150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2. Seven days after the transplant plants were photographed (Figure 1A) and rosette areas and fresh weights were determined (Figure 1). B. phytofirmans treatment produced a significant 87 ± 20% increase in rosette area in stressed plants (Figure 1B, left). Fresh weight was also significantly higher (97 ± 21%) in plants treated with strain PsJN and exposed to salinity (Figure 1B, right). Also, primary root length was increased in inoculated and stressed plants (Supplementary Figure S1). In addition, a treatment with heat-killed bacteria (K-PsJN) was incorporated as described by Poupin et al. (2013), to discriminate the effects of metabolically active bacteria from those of inactive bacteria on plants under salt-stress. Treatment with K-PsJN had no effect on A. thaliana growth, neither on MS media nor under salt-stress (Supplementary Figure S1).


Burkholderia phytofirmans PsJN induces long-term metabolic and transcriptional changes involved in Arabidopsis thaliana salt tolerance.

Pinedo I, Ledger T, Greve M, Poupin MJ - Front Plant Sci (2015)

Effects of Burkholderia phytofirmans PsJN on Arabidopsis thaliana growth in vitro. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 days after sowing (DAS) to Murashige Skoog (MS) with or without addition of salt (150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2). Data was collected 7 days after transplantation. (B) Graphic representation of rosette area (left) and fresh weight (right) of plants treated under the experimental conditions described before. Data are means ± 1 SE of at least 20 plants per treatment. Asterisks indicate significant differences between control and PsJN treatment (Two-way ANOVA, p < 0.05; Bonferroni test, ∗∗∗P < 0.01). Results are representative of two different experiments. White bars in photographs correspond to 2 cm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477060&req=5

Figure 1: Effects of Burkholderia phytofirmans PsJN on Arabidopsis thaliana growth in vitro. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 days after sowing (DAS) to Murashige Skoog (MS) with or without addition of salt (150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2). Data was collected 7 days after transplantation. (B) Graphic representation of rosette area (left) and fresh weight (right) of plants treated under the experimental conditions described before. Data are means ± 1 SE of at least 20 plants per treatment. Asterisks indicate significant differences between control and PsJN treatment (Two-way ANOVA, p < 0.05; Bonferroni test, ∗∗∗P < 0.01). Results are representative of two different experiments. White bars in photographs correspond to 2 cm.
Mentions: To address for differences in growth of A. thaliana Col-0 plants exposed to salt-stress in vitro, seeds were sown in half strength Murashige and Skoog (1962) media (MS1/2) with or without inoculation of strain PsJN as described in the “Materials and Methods” section. At 11 DAS, plants were transferred to MS1/2 media containing different salt concentrations ranging from 150 mM NaCl/15 mM CaCl2 to 250 mM NaCl/25 mM CaCl2. Seven days after the transplant plants were photographed (Figure 1A) and rosette areas and fresh weights were determined (Figure 1). B. phytofirmans treatment produced a significant 87 ± 20% increase in rosette area in stressed plants (Figure 1B, left). Fresh weight was also significantly higher (97 ± 21%) in plants treated with strain PsJN and exposed to salinity (Figure 1B, right). Also, primary root length was increased in inoculated and stressed plants (Supplementary Figure S1). In addition, a treatment with heat-killed bacteria (K-PsJN) was incorporated as described by Poupin et al. (2013), to discriminate the effects of metabolically active bacteria from those of inactive bacteria on plants under salt-stress. Treatment with K-PsJN had no effect on A. thaliana growth, neither on MS media nor under salt-stress (Supplementary Figure S1).

Bottom Line: Among the general transcriptional effects of this bacterium, the expression pattern of important ion-homeostasis related genes was altered after short and long-term stress (Arabidopsis K(+) Transporter 1, High-Affinity K(+) Transporter 1, Sodium Hydrogen Exchanger 2, and Arabidopsis Salt Overly Sensitive 1).In all, the faster and stronger molecular changes induced by the inoculation suggest a PsJN-priming effect, which may explain the observed tolerance after short-term and sustained salt-stress in plants.This opens up new venues to study these relevant biological associations, as well as new approaches to a better understanding of the spatiotemporal mechanisms involved in stress tolerance in plants.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez Santiago, Chile.

ABSTRACT
Salinity is one of the major limitations for food production worldwide. Improvement of plant salt-stress tolerance using plant-growth promoting rhizobacteria (PGPR) has arisen as a promising strategy to help overcome this limitation. However, the molecular and biochemical mechanisms controlling PGPR/plant interactions under salt-stress remain unclear. The main objective of this study was to obtain new insights into the mechanisms underlying salt-stress tolerance enhancement in the salt-sensitive Arabidopsis thaliana Col-0 plants, when inoculated with the well-known PGPR strain Burkholderia phytofirmans PsJN. To tackle this, different life history traits, together with the spatiotemporal accumulation patterns for key metabolites and salt-stress related transcripts, were analyzed in inoculated plants under short and long-term salt-stress. Inoculated plants displayed faster recovery and increased tolerance after sustained salt-stress. PsJN treatment accelerated the accumulation of proline and transcription of genes related to abscisic acid signaling (Relative to Dessication, RD29A and RD29B), ROS scavenging (Ascorbate Peroxidase 2), and detoxification (Glyoxalase I 7), and down-regulated the expression of Lipoxygenase 2 (related to jasmonic acid biosynthesis). Among the general transcriptional effects of this bacterium, the expression pattern of important ion-homeostasis related genes was altered after short and long-term stress (Arabidopsis K(+) Transporter 1, High-Affinity K(+) Transporter 1, Sodium Hydrogen Exchanger 2, and Arabidopsis Salt Overly Sensitive 1). In all, the faster and stronger molecular changes induced by the inoculation suggest a PsJN-priming effect, which may explain the observed tolerance after short-term and sustained salt-stress in plants. This study provides novel information about possible mechanisms involved in salt-stress tolerance induced by PGPR in plants, showing that certain changes are maintained over time. This opens up new venues to study these relevant biological associations, as well as new approaches to a better understanding of the spatiotemporal mechanisms involved in stress tolerance in plants.

No MeSH data available.


Related in: MedlinePlus