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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 B. phytofirmans PsJN on A. thaliana long-term growth in saline media. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 DAS to individual pots with a 2:1 mix of peat/vermiculite and irrigated periodically with saline solution containing 150 mM NaCl/15 mM CaCl2. (B) Graphic representation of average rosette area (growth rate is indicated for the first and last periods of the experiment, cm2/d. (C,D) Percentage of non-green area of non-inoculated (C) and inoculated (D) plant rosettes under the experimental condition described. Data are means ± 1 SE of at least eight plants per treatment. Asterisks indicate significant differences between control and PsJN treatment in each time point (t-student, p < 0.05; Welch’s correction, ∗P < 0.1; ∗∗P < 0.05; ∗∗∗P < 0.01). Whitebars in photograph correspond to 2 cm.
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Figure 3: Effects of B. phytofirmans PsJN on A. thaliana long-term growth in saline media. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 DAS to individual pots with a 2:1 mix of peat/vermiculite and irrigated periodically with saline solution containing 150 mM NaCl/15 mM CaCl2. (B) Graphic representation of average rosette area (growth rate is indicated for the first and last periods of the experiment, cm2/d. (C,D) Percentage of non-green area of non-inoculated (C) and inoculated (D) plant rosettes under the experimental condition described. Data are means ± 1 SE of at least eight plants per treatment. Asterisks indicate significant differences between control and PsJN treatment in each time point (t-student, p < 0.05; Welch’s correction, ∗P < 0.1; ∗∗P < 0.05; ∗∗∗P < 0.01). Whitebars in photograph correspond to 2 cm.

Mentions: To explore a long-term salt-stress tolerance in Arabidopsis, plants were inoculated as described in the “Materials and Methods” section, transferred to soil and stressed by periodically irrigating with a saline solution (150 mM NaCl/15 mM CaCl2). Rosette areas were higher in inoculated plants after 35 days of stress (Figures 3A,B). During the first 14 days under stress, growth rate of inoculated plants was significantly higher than the non-inoculated plants (0.36 cm2/d vs. 0.27 cm2/d, respectively; Figure 3B). During the final stage of the stress treatment the rosette area of non-inoculated plants decreased (wilted) in a significantly higher rate (-0.08 cm2/d) than the inoculated plants (-0.04 cm2/d; Figure 3B). Also, stressed foliar areas were determined analyzing the color pattern of plant images, to quantify the recession of green colored leaf area caused by stress. Interestingly, inoculated plants showed significantly larger green areas than the non-inoculated plants (Figures 3C,D). Control non-stressed plants began to lose green coloration only at 50 DAS (data not shown).


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 B. phytofirmans PsJN on A. thaliana long-term growth in saline media. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 DAS to individual pots with a 2:1 mix of peat/vermiculite and irrigated periodically with saline solution containing 150 mM NaCl/15 mM CaCl2. (B) Graphic representation of average rosette area (growth rate is indicated for the first and last periods of the experiment, cm2/d. (C,D) Percentage of non-green area of non-inoculated (C) and inoculated (D) plant rosettes under the experimental condition described. Data are means ± 1 SE of at least eight plants per treatment. Asterisks indicate significant differences between control and PsJN treatment in each time point (t-student, p < 0.05; Welch’s correction, ∗P < 0.1; ∗∗P < 0.05; ∗∗∗P < 0.01). Whitebars in photograph correspond to 2 cm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Effects of B. phytofirmans PsJN on A. thaliana long-term growth in saline media. (A) Representative photographs of A. thaliana plants treated with or without B. phytofirmans PsJN, and transplanted at 11 DAS to individual pots with a 2:1 mix of peat/vermiculite and irrigated periodically with saline solution containing 150 mM NaCl/15 mM CaCl2. (B) Graphic representation of average rosette area (growth rate is indicated for the first and last periods of the experiment, cm2/d. (C,D) Percentage of non-green area of non-inoculated (C) and inoculated (D) plant rosettes under the experimental condition described. Data are means ± 1 SE of at least eight plants per treatment. Asterisks indicate significant differences between control and PsJN treatment in each time point (t-student, p < 0.05; Welch’s correction, ∗P < 0.1; ∗∗P < 0.05; ∗∗∗P < 0.01). Whitebars in photograph correspond to 2 cm.
Mentions: To explore a long-term salt-stress tolerance in Arabidopsis, plants were inoculated as described in the “Materials and Methods” section, transferred to soil and stressed by periodically irrigating with a saline solution (150 mM NaCl/15 mM CaCl2). Rosette areas were higher in inoculated plants after 35 days of stress (Figures 3A,B). During the first 14 days under stress, growth rate of inoculated plants was significantly higher than the non-inoculated plants (0.36 cm2/d vs. 0.27 cm2/d, respectively; Figure 3B). During the final stage of the stress treatment the rosette area of non-inoculated plants decreased (wilted) in a significantly higher rate (-0.08 cm2/d) than the inoculated plants (-0.04 cm2/d; Figure 3B). Also, stressed foliar areas were determined analyzing the color pattern of plant images, to quantify the recession of green colored leaf area caused by stress. Interestingly, inoculated plants showed significantly larger green areas than the non-inoculated plants (Figures 3C,D). Control non-stressed plants began to lose green coloration only at 50 DAS (data not shown).

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