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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

Growth of virulent and avirulent Pst in various PLD knockout mutants.Arabidopsis leaves attached to the plant were infiltrated with a suspension of Pst DC3000 (A) or DC3000:AvrRpm1 (B). The bacteria in the leaves were extracted immediately or after 3 days and quantified by serial dilution and cultivation on solid medium. Average and SD of three replicates is shown. An asterisk indicates statistically significant differences from wild type (Col-0) at 3 dpi. The experiments shown were repeated twice with similar results.
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Figure 5: Growth of virulent and avirulent Pst in various PLD knockout mutants.Arabidopsis leaves attached to the plant were infiltrated with a suspension of Pst DC3000 (A) or DC3000:AvrRpm1 (B). The bacteria in the leaves were extracted immediately or after 3 days and quantified by serial dilution and cultivation on solid medium. Average and SD of three replicates is shown. An asterisk indicates statistically significant differences from wild type (Col-0) at 3 dpi. The experiments shown were repeated twice with similar results.

Mentions: We next tested the different Arabidopsis lines for their ability to restrict growth of the virulent Pst DC3000 and the avirulent strain DC3000:AvrRpm1. As expected, over a period of 3 days DC3000 multiplied in wild type leaves by about a thousand times (Figure 5A). The growth of DC3000 was not significantly affected in any of the tested mutant lines. The avirulent strain DC3000:AvrRpm1 grew about 10-fold in 2 days in wild type Col-0 and this was not significantly affected in any of the tested mutants (Figure 5B). The rpm1-3 mutant, which is unable to recognize AvrRpm1, demonstrated bacterial multiplication by about 10000 times. To conclude, none of the tested PLD single, double or triple mutants demonstrated any apparent change in resistance toward virulent and avirulent Pst DC3000.


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)

Growth of virulent and avirulent Pst in various PLD knockout mutants.Arabidopsis leaves attached to the plant were infiltrated with a suspension of Pst DC3000 (A) or DC3000:AvrRpm1 (B). The bacteria in the leaves were extracted immediately or after 3 days and quantified by serial dilution and cultivation on solid medium. Average and SD of three replicates is shown. An asterisk indicates statistically significant differences from wild type (Col-0) at 3 dpi. The experiments shown were repeated twice with similar results.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Growth of virulent and avirulent Pst in various PLD knockout mutants.Arabidopsis leaves attached to the plant were infiltrated with a suspension of Pst DC3000 (A) or DC3000:AvrRpm1 (B). The bacteria in the leaves were extracted immediately or after 3 days and quantified by serial dilution and cultivation on solid medium. Average and SD of three replicates is shown. An asterisk indicates statistically significant differences from wild type (Col-0) at 3 dpi. The experiments shown were repeated twice with similar results.
Mentions: We next tested the different Arabidopsis lines for their ability to restrict growth of the virulent Pst DC3000 and the avirulent strain DC3000:AvrRpm1. As expected, over a period of 3 days DC3000 multiplied in wild type leaves by about a thousand times (Figure 5A). The growth of DC3000 was not significantly affected in any of the tested mutant lines. The avirulent strain DC3000:AvrRpm1 grew about 10-fold in 2 days in wild type Col-0 and this was not significantly affected in any of the tested mutants (Figure 5B). The rpm1-3 mutant, which is unable to recognize AvrRpm1, demonstrated bacterial multiplication by about 10000 times. To conclude, none of the tested PLD single, double or triple mutants demonstrated any apparent change in resistance toward virulent and avirulent Pst DC3000.

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