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Genomic screens identify a new phytobacterial microbe-associated molecular pattern and the cognate Arabidopsis receptor-like kinase that mediates its immune elicitation.

Mott GA, Thakur S, Smakowska E, Wang PW, Belkhadir Y, Desveaux D, Guttman DS - Genome Biol. (2016)

Bottom Line: We test the six elicitors on 187 receptor-like kinase knock-down insertion lines using a high-throughput peroxidase-based immune assay and identify multiple lines that show decreased immune responses to specific peptides.These results identify xup25 as a P. syringae microbe-associated molecular pattern and xanthine/uracil permease sensing 1 as a receptor-like kinase that detects the xup25 epitope to activate immune responses.The present study demonstrates an efficient method to identify immune elicitors and the plant receptors responsible for their perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada.

ABSTRACT

Background: The recognition of microbe-associated molecular patterns during infection is central to the mounting of an effective immune response. In spite of their importance, it remains difficult to identify these molecules and the host receptors required for their perception, ultimately limiting our understanding of the role of these molecules in the evolution of host-pathogen relationships.

Results: We employ a comparative genomics screen to identify six new immune eliciting peptides from the phytopathogenic bacterium Pseudomonas syringae. We then perform a reverse genetic screen to identify Arabidopsis thaliana leucine-rich repeat receptor-like kinases required for the recognition of these elicitors. We test the six elicitors on 187 receptor-like kinase knock-down insertion lines using a high-throughput peroxidase-based immune assay and identify multiple lines that show decreased immune responses to specific peptides. From this primary screen data, we focused on the interaction between the xup25 peptide from a bacterial xanthine/uracil permease and the Arabidopsis receptor-like kinase xanthine/uracil permease sensing 1; a family XII protein closely related to two well-characterized receptor-like kinases. We show that xup25 treatment increases pathogenesis-related gene induction, callose deposition, seedling growth inhibition, and resistance to virulent bacteria, all in a xanthine/uracil permease sensing 1-dependent manner. Finally, we show that this kinase-like receptor can bind the xup25 peptide directly. These results identify xup25 as a P. syringae microbe-associated molecular pattern and xanthine/uracil permease sensing 1 as a receptor-like kinase that detects the xup25 epitope to activate immune responses.

Conclusions: The present study demonstrates an efficient method to identify immune elicitors and the plant receptors responsible for their perception. Further exploration of these molecules will increase our understanding of plant-pathogen interactions and the basis for host specificity.

No MeSH data available.


Related in: MedlinePlus

xup25-induced callose deposition is XPS1-dependent. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide. After 24 h of treatment the leaves were harvested, cleared, and callose deposits were stained prior to epifluorescent microscopy. a The proportion of the image with callose present was determined and data from a single representative trial is shown (n = 6, *P <0.05, ***P <0.001, pairwise Student’s t-test, corrected with Holm-Bonferroni). b Representative images of the callose deposits for each treatment are shown. Callose deposits are indicated by dark spots; the images have been converted to gray scale and inverted. The experiment was repeated four times in total with similar results, for a total n = 26
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Fig6: xup25-induced callose deposition is XPS1-dependent. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide. After 24 h of treatment the leaves were harvested, cleared, and callose deposits were stained prior to epifluorescent microscopy. a The proportion of the image with callose present was determined and data from a single representative trial is shown (n = 6, *P <0.05, ***P <0.001, pairwise Student’s t-test, corrected with Holm-Bonferroni). b Representative images of the callose deposits for each treatment are shown. Callose deposits are indicated by dark spots; the images have been converted to gray scale and inverted. The experiment was repeated four times in total with similar results, for a total n = 26

Mentions: Another well-characterized marker of MAMP treatment is the deposition of callose to reinforce the plant cell wall [25]. We measured the levels of callose deposition following 24 h of treatment with flg22 or xup25. The treatment of Col-0 plants led to increased callose deposition in response to both peptides, whereas the xps1 line showed callose deposition when treated with flg22 but not xup25, which showed no difference from the water control (Fig. 6 and Additional file 7: Figure S6).Fig. 6


Genomic screens identify a new phytobacterial microbe-associated molecular pattern and the cognate Arabidopsis receptor-like kinase that mediates its immune elicitation.

Mott GA, Thakur S, Smakowska E, Wang PW, Belkhadir Y, Desveaux D, Guttman DS - Genome Biol. (2016)

xup25-induced callose deposition is XPS1-dependent. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide. After 24 h of treatment the leaves were harvested, cleared, and callose deposits were stained prior to epifluorescent microscopy. a The proportion of the image with callose present was determined and data from a single representative trial is shown (n = 6, *P <0.05, ***P <0.001, pairwise Student’s t-test, corrected with Holm-Bonferroni). b Representative images of the callose deposits for each treatment are shown. Callose deposits are indicated by dark spots; the images have been converted to gray scale and inverted. The experiment was repeated four times in total with similar results, for a total n = 26
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4862170&req=5

Fig6: xup25-induced callose deposition is XPS1-dependent. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide. After 24 h of treatment the leaves were harvested, cleared, and callose deposits were stained prior to epifluorescent microscopy. a The proportion of the image with callose present was determined and data from a single representative trial is shown (n = 6, *P <0.05, ***P <0.001, pairwise Student’s t-test, corrected with Holm-Bonferroni). b Representative images of the callose deposits for each treatment are shown. Callose deposits are indicated by dark spots; the images have been converted to gray scale and inverted. The experiment was repeated four times in total with similar results, for a total n = 26
Mentions: Another well-characterized marker of MAMP treatment is the deposition of callose to reinforce the plant cell wall [25]. We measured the levels of callose deposition following 24 h of treatment with flg22 or xup25. The treatment of Col-0 plants led to increased callose deposition in response to both peptides, whereas the xps1 line showed callose deposition when treated with flg22 but not xup25, which showed no difference from the water control (Fig. 6 and Additional file 7: Figure S6).Fig. 6

Bottom Line: We test the six elicitors on 187 receptor-like kinase knock-down insertion lines using a high-throughput peroxidase-based immune assay and identify multiple lines that show decreased immune responses to specific peptides.These results identify xup25 as a P. syringae microbe-associated molecular pattern and xanthine/uracil permease sensing 1 as a receptor-like kinase that detects the xup25 epitope to activate immune responses.The present study demonstrates an efficient method to identify immune elicitors and the plant receptors responsible for their perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada.

ABSTRACT

Background: The recognition of microbe-associated molecular patterns during infection is central to the mounting of an effective immune response. In spite of their importance, it remains difficult to identify these molecules and the host receptors required for their perception, ultimately limiting our understanding of the role of these molecules in the evolution of host-pathogen relationships.

Results: We employ a comparative genomics screen to identify six new immune eliciting peptides from the phytopathogenic bacterium Pseudomonas syringae. We then perform a reverse genetic screen to identify Arabidopsis thaliana leucine-rich repeat receptor-like kinases required for the recognition of these elicitors. We test the six elicitors on 187 receptor-like kinase knock-down insertion lines using a high-throughput peroxidase-based immune assay and identify multiple lines that show decreased immune responses to specific peptides. From this primary screen data, we focused on the interaction between the xup25 peptide from a bacterial xanthine/uracil permease and the Arabidopsis receptor-like kinase xanthine/uracil permease sensing 1; a family XII protein closely related to two well-characterized receptor-like kinases. We show that xup25 treatment increases pathogenesis-related gene induction, callose deposition, seedling growth inhibition, and resistance to virulent bacteria, all in a xanthine/uracil permease sensing 1-dependent manner. Finally, we show that this kinase-like receptor can bind the xup25 peptide directly. These results identify xup25 as a P. syringae microbe-associated molecular pattern and xanthine/uracil permease sensing 1 as a receptor-like kinase that detects the xup25 epitope to activate immune responses.

Conclusions: The present study demonstrates an efficient method to identify immune elicitors and the plant receptors responsible for their perception. Further exploration of these molecules will increase our understanding of plant-pathogen interactions and the basis for host specificity.

No MeSH data available.


Related in: MedlinePlus