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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 protects from pathogen challenge in an XPS1-dependent manner. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide 24 h prior to infiltration with Pto DC3000 (0.0005 OD). Tissue was harvested after 24 h of in planta bacterial growth and lysates were plated on selective media. Data from a single representative experiment is shown (mean +/- s.e., n = 6, *P <0.05, **P <0.01, ***P <0.001, ns not statistically significant, pairwise Student’s t-test, corrected with Holm-Bonferroni). Each experiment was repeated three times with similar results. cfu, colony forming units. No significant difference was observed between Col-0 and xps1-1 plants treated with flg22
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Fig7: xup25 protects from pathogen challenge in an XPS1-dependent manner. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide 24 h prior to infiltration with Pto DC3000 (0.0005 OD). Tissue was harvested after 24 h of in planta bacterial growth and lysates were plated on selective media. Data from a single representative experiment is shown (mean +/- s.e., n = 6, *P <0.05, **P <0.01, ***P <0.001, ns not statistically significant, pairwise Student’s t-test, corrected with Holm-Bonferroni). Each experiment was repeated three times with similar results. cfu, colony forming units. No significant difference was observed between Col-0 and xps1-1 plants treated with flg22

Mentions: The ultimate aim of the immune response is to increase pathogen resistance by suppressing colonization and growth of microbes in plant tissues. To measure elicitor-induced pathogen resistance, and to test the role of XPS1 in suppressing pathogen growth in response to xup25, we performed a virulence suppression assay by pre-treating plants with flg22 or xup25 peptides for 24 h, and then challenging the plants with the highly virulent strain P. syringae pv. tomato DC3000 (Pto DC3000) via pressure infiltration. Plants that are pre-treated with immune-eliciting peptides should show lower levels of pathogen growth. Both Col-0 and xps1 plants pre-treated with flg22 significantly suppressed in planta growth of Pto DC3000 24 h post infection (Fig. 7). In contrast, while xup25 pre-treatment was able to suppress Pto DC3000 growth in Col-0, it did not suppress pathogen growth in the xps1 background, resulting in bacterial densities indistinguishable from the water-treated controls.Fig. 7


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 protects from pathogen challenge in an XPS1-dependent manner. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide 24 h prior to infiltration with Pto DC3000 (0.0005 OD). Tissue was harvested after 24 h of in planta bacterial growth and lysates were plated on selective media. Data from a single representative experiment is shown (mean +/- s.e., n = 6, *P <0.05, **P <0.01, ***P <0.001, ns not statistically significant, pairwise Student’s t-test, corrected with Holm-Bonferroni). Each experiment was repeated three times with similar results. cfu, colony forming units. No significant difference was observed between Col-0 and xps1-1 plants treated with flg22
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4862170&req=5

Fig7: xup25 protects from pathogen challenge in an XPS1-dependent manner. Leaves from A. thaliana ecotype Col-0 or xps1-1 plants were pressure infiltrated with water or 10 μM of peptide 24 h prior to infiltration with Pto DC3000 (0.0005 OD). Tissue was harvested after 24 h of in planta bacterial growth and lysates were plated on selective media. Data from a single representative experiment is shown (mean +/- s.e., n = 6, *P <0.05, **P <0.01, ***P <0.001, ns not statistically significant, pairwise Student’s t-test, corrected with Holm-Bonferroni). Each experiment was repeated three times with similar results. cfu, colony forming units. No significant difference was observed between Col-0 and xps1-1 plants treated with flg22
Mentions: The ultimate aim of the immune response is to increase pathogen resistance by suppressing colonization and growth of microbes in plant tissues. To measure elicitor-induced pathogen resistance, and to test the role of XPS1 in suppressing pathogen growth in response to xup25, we performed a virulence suppression assay by pre-treating plants with flg22 or xup25 peptides for 24 h, and then challenging the plants with the highly virulent strain P. syringae pv. tomato DC3000 (Pto DC3000) via pressure infiltration. Plants that are pre-treated with immune-eliciting peptides should show lower levels of pathogen growth. Both Col-0 and xps1 plants pre-treated with flg22 significantly suppressed in planta growth of Pto DC3000 24 h post infection (Fig. 7). In contrast, while xup25 pre-treatment was able to suppress Pto DC3000 growth in Col-0, it did not suppress pathogen growth in the xps1 background, resulting in bacterial densities indistinguishable from the water-treated controls.Fig. 7

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