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Redundancy among phospholipase D isoforms in resistance triggered by recognition of the Pseudomonas syringae effector AvrRpm1 in Arabidopsis thaliana.

Johansson ON, Fahlberg P, Karimi E, Nilsson AK, Ellerström M, Andersson MX - Front Plant Sci (2014)

Bottom Line: Recognition of microbial effectors or their activity by plant resistance (R)-proteins triggers a second line of defense resulting in effector triggered immunity (ETI).However, repression of PLD dependent PA production by n-butanol strongly inhibited the HR following Pseudomonas syringae effector recognition.Thus, the effect of mutations of PLDs could become detectable, and the corresponding genes can be proposed to be involved in the HR.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Environmental Sciences, University of Gothenburg Gothenburg, Sweden.

ABSTRACT
Plants possess a highly sophisticated system for defense against microorganisms. So called MAMP (microbe-associated molecular patterns) triggered immunity (MTI) prevents the majority of non-adapted pathogens from causing disease. Adapted plant pathogens use secreted effector proteins to interfere with such signaling. Recognition of microbial effectors or their activity by plant resistance (R)-proteins triggers a second line of defense resulting in effector triggered immunity (ETI). The latter usually comprises the hypersensitive response (HR) which includes programmed cell death at the site of infection. Phospholipase D (PLD) mediated production of phosphatidic acid (PA) has been linked to both MTI and ETI in plants. Inhibition of PLD activity has been shown to attenuate MTI as well as ETI. In this study, we systematically tested single and double knockouts in all 12 genes encoding PLDs in Arabidopsis thaliana for effects on ETI and MTI. No single PLD could be linked to ETI triggered by recognition of effectors secreted by the bacterium Pseudomonas syringae. However, repression of PLD dependent PA production by n-butanol strongly inhibited the HR following Pseudomonas syringae effector recognition. In addition some pld mutants were more sensitive to n-butanol than wild type. Thus, the effect of mutations of PLDs could become detectable, and the corresponding genes can be proposed to be involved in the HR. Only knockout of PLDδ caused a loss of MTI-induced cell wall based defense against the non-host powdery mildew Erysiphe pisi. This is thus in stark contrast to the involvement of a multitude of PLD isoforms in the HR triggered by AvrRpm1 recognition.

No MeSH data available.


Related in: MedlinePlus

Formation of Phosphatidybutanol (PBut) in Arabidopsis leaf tissue during the HR in the presence of n-butanol. Leaf discs were prepared from wild type, Col-0, Arabidopsis, infiltrated with Pst DC3000:AvrRpm1 or MgCl2 (mock treatment) in 0.6% tert- or n-butanol water solutions and incubated in deionized water with the same alcohol at the same concentration for 4 h. The lipids were extracted and the amount of PBut formed analyzed by LC-MS/MS. An asterisk indicates a statistically significant (p < 0.05, one way ANOVA) difference between mock treatment and infiltration with Pst DC3000:AvrRpm1.
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Figure 2: Formation of Phosphatidybutanol (PBut) in Arabidopsis leaf tissue during the HR in the presence of n-butanol. Leaf discs were prepared from wild type, Col-0, Arabidopsis, infiltrated with Pst DC3000:AvrRpm1 or MgCl2 (mock treatment) in 0.6% tert- or n-butanol water solutions and incubated in deionized water with the same alcohol at the same concentration for 4 h. The lipids were extracted and the amount of PBut formed analyzed by LC-MS/MS. An asterisk indicates a statistically significant (p < 0.05, one way ANOVA) difference between mock treatment and infiltration with Pst DC3000:AvrRpm1.

Mentions: Lipids were extracted from three Arabidopsis leaf discs prepared and incubated as above by chloroform methanol extraction as previously described (Andersson et al., 2006) after addition of 0.1 μg of diheptadecanoyl phosphatidylcholine as internal standard. Phosphatidybutanol (PBut) species were analyzed by LC-MS/MS using the chromatographic conditions and instrumental settings previously described (Nilsson et al., 2014) using the MRM transitions described for PBut species (Rainteau et al., 2012). The following molecular species of PBut could be detected: 18:3/18:3, 18:2/18:3, 16:0/18:3, 18:2/18:2, 18:1/18:3, 16:0/18:2, 18:1/18:2, 18:0/18:2. The sum of the mass spectrometric signal for these species divided by that of the internal standard is presented in Figure 2.


Redundancy among phospholipase D isoforms in resistance triggered by recognition of the Pseudomonas syringae effector AvrRpm1 in Arabidopsis thaliana.

Johansson ON, Fahlberg P, Karimi E, Nilsson AK, Ellerström M, Andersson MX - Front Plant Sci (2014)

Formation of Phosphatidybutanol (PBut) in Arabidopsis leaf tissue during the HR in the presence of n-butanol. Leaf discs were prepared from wild type, Col-0, Arabidopsis, infiltrated with Pst DC3000:AvrRpm1 or MgCl2 (mock treatment) in 0.6% tert- or n-butanol water solutions and incubated in deionized water with the same alcohol at the same concentration for 4 h. The lipids were extracted and the amount of PBut formed analyzed by LC-MS/MS. An asterisk indicates a statistically significant (p < 0.05, one way ANOVA) difference between mock treatment and infiltration with Pst DC3000:AvrRpm1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230166&req=5

Figure 2: Formation of Phosphatidybutanol (PBut) in Arabidopsis leaf tissue during the HR in the presence of n-butanol. Leaf discs were prepared from wild type, Col-0, Arabidopsis, infiltrated with Pst DC3000:AvrRpm1 or MgCl2 (mock treatment) in 0.6% tert- or n-butanol water solutions and incubated in deionized water with the same alcohol at the same concentration for 4 h. The lipids were extracted and the amount of PBut formed analyzed by LC-MS/MS. An asterisk indicates a statistically significant (p < 0.05, one way ANOVA) difference between mock treatment and infiltration with Pst DC3000:AvrRpm1.
Mentions: Lipids were extracted from three Arabidopsis leaf discs prepared and incubated as above by chloroform methanol extraction as previously described (Andersson et al., 2006) after addition of 0.1 μg of diheptadecanoyl phosphatidylcholine as internal standard. Phosphatidybutanol (PBut) species were analyzed by LC-MS/MS using the chromatographic conditions and instrumental settings previously described (Nilsson et al., 2014) using the MRM transitions described for PBut species (Rainteau et al., 2012). The following molecular species of PBut could be detected: 18:3/18:3, 18:2/18:3, 16:0/18:3, 18:2/18:2, 18:1/18:3, 16:0/18:2, 18:1/18:2, 18:0/18:2. The sum of the mass spectrometric signal for these species divided by that of the internal standard is presented in Figure 2.

Bottom Line: Recognition of microbial effectors or their activity by plant resistance (R)-proteins triggers a second line of defense resulting in effector triggered immunity (ETI).However, repression of PLD dependent PA production by n-butanol strongly inhibited the HR following Pseudomonas syringae effector recognition.Thus, the effect of mutations of PLDs could become detectable, and the corresponding genes can be proposed to be involved in the HR.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Environmental Sciences, University of Gothenburg Gothenburg, Sweden.

ABSTRACT
Plants possess a highly sophisticated system for defense against microorganisms. So called MAMP (microbe-associated molecular patterns) triggered immunity (MTI) prevents the majority of non-adapted pathogens from causing disease. Adapted plant pathogens use secreted effector proteins to interfere with such signaling. Recognition of microbial effectors or their activity by plant resistance (R)-proteins triggers a second line of defense resulting in effector triggered immunity (ETI). The latter usually comprises the hypersensitive response (HR) which includes programmed cell death at the site of infection. Phospholipase D (PLD) mediated production of phosphatidic acid (PA) has been linked to both MTI and ETI in plants. Inhibition of PLD activity has been shown to attenuate MTI as well as ETI. In this study, we systematically tested single and double knockouts in all 12 genes encoding PLDs in Arabidopsis thaliana for effects on ETI and MTI. No single PLD could be linked to ETI triggered by recognition of effectors secreted by the bacterium Pseudomonas syringae. However, repression of PLD dependent PA production by n-butanol strongly inhibited the HR following Pseudomonas syringae effector recognition. In addition some pld mutants were more sensitive to n-butanol than wild type. Thus, the effect of mutations of PLDs could become detectable, and the corresponding genes can be proposed to be involved in the HR. Only knockout of PLDδ caused a loss of MTI-induced cell wall based defense against the non-host powdery mildew Erysiphe pisi. This is thus in stark contrast to the involvement of a multitude of PLD isoforms in the HR triggered by AvrRpm1 recognition.

No MeSH data available.


Related in: MedlinePlus