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Microbe-associated molecular pattern-induced calcium signaling requires the receptor-like cytoplasmic kinases, PBL1 and BIK1.

Ranf S, Eschen-Lippold L, Fröhlich K, Westphal L, Scheel D, Lee J - BMC Plant Biol. (2014)

Bottom Line: They all show reduced calcium levels after elicitation with peptides representing bacteria-derived MAMPs (flg22 and elf18) and endogenous DAMP (AtPep1), but a normal response to chitin octamers.Validation with T-DNA mutants revealed that, besides PBL1, another RLCK, Botrytis-induced kinase 1 (BIK1), is also required for MAMP/DAMP-induced calcium elevations.Hence, PBL1 and BIK1 (but not two related RLCKs, PBS1 and PBL2) are required for MAMP/DAMP-induced calcium signaling.

View Article: PubMed Central - PubMed

Affiliation: Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Weinberg 3, Halle/Saale, D-06120, Germany. ranf@wzw.tum.de.

ABSTRACT

Background: Plant perception of conserved microbe-derived or damage-derived molecules (so-called microbe- or damage-associated molecular patterns, MAMPs or DAMPs, respectively) triggers cellular signaling cascades to initiate counteracting defence responses. Using MAMP-induced rise in cellular calcium levels as one of the earliest biochemical readouts, we initiated a genetic screen for components involved in early MAMP signaling in Arabidopsis thaliana.

Results: We characterized here the "changed calcium elevation 5" (cce5) mutant, where five allelic cce5 mutants were isolated. They all show reduced calcium levels after elicitation with peptides representing bacteria-derived MAMPs (flg22 and elf18) and endogenous DAMP (AtPep1), but a normal response to chitin octamers. Mapping, sequencing of the mutated locus and complementation studies revealed CCE5 to encode the receptor-like cytoplasmic kinase (RLCK), avrPphB sensitive 1-like 1 (PBL1). Kinase activities of PBL1 derived from three of the cce5 alleles are abrogated in vivo. Validation with T-DNA mutants revealed that, besides PBL1, another RLCK, Botrytis-induced kinase 1 (BIK1), is also required for MAMP/DAMP-induced calcium elevations.

Conclusions: Hence, PBL1 and BIK1 (but not two related RLCKs, PBS1 and PBL2) are required for MAMP/DAMP-induced calcium signaling. It remains to be investigated if the many other RLCKs encoded in the Arabidopsis genome affect early calcium signal transduction - perhaps in dependence on the type of MAMP/DAMP ligands. A future challenge would be to identify the substrates of these various RLCKs, in order to elucidate their signaling role between the receptor complexes at the plasma membrane and downstream cellular signaling components.

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CCE5is not allelic toBAK1,SERK4orSERK5. The cce5-1 allele was crossed to bak1-4 (left panel) or to serk4 or serk5 mutants (right panel). Crosses with Col-0 or the HVA1 parent were used as controls. Relative calcium (L/Lmax) levels were determined in the F1 crosses after elf18 (1 μM) treatment – showing that the cce5 phenotype was complemented when crossed with the bak1, serk4 and serk5 mutants and therefore not allelic to these genes. (n = 8–14 seedlings)
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Fig3: CCE5is not allelic toBAK1,SERK4orSERK5. The cce5-1 allele was crossed to bak1-4 (left panel) or to serk4 or serk5 mutants (right panel). Crosses with Col-0 or the HVA1 parent were used as controls. Relative calcium (L/Lmax) levels were determined in the F1 crosses after elf18 (1 μM) treatment – showing that the cce5 phenotype was complemented when crossed with the bak1, serk4 and serk5 mutants and therefore not allelic to these genes. (n = 8–14 seedlings)

Mentions: BAK1 is the BRI1-associated receptor kinase shown to interact with FLS2, EFR and PEPR1/R2 receptors in a ligand-dependent manner [29]. To exclude that the cce5 mutants are weak alleles of BAK1 or the related SOMATIC EMBRYOGENESIS RELATED KINASE (SERK) members, cce5-1 was crossed to the mutants bak1-4, serk4-1 and serk5-1 [5]. Since the cce5 effect was most prominent for elf18 elicitation, we measured elf18-induced calcium fluxes in F1 seedlings, and observed that the cce5 phenotype was complemented (Figure 3). This result indicates that CCE5 is not allelic to BAK1, SERK4 or SERK5 and hence cce5 is mutated in a different gene.Figure 3


Microbe-associated molecular pattern-induced calcium signaling requires the receptor-like cytoplasmic kinases, PBL1 and BIK1.

Ranf S, Eschen-Lippold L, Fröhlich K, Westphal L, Scheel D, Lee J - BMC Plant Biol. (2014)

CCE5is not allelic toBAK1,SERK4orSERK5. The cce5-1 allele was crossed to bak1-4 (left panel) or to serk4 or serk5 mutants (right panel). Crosses with Col-0 or the HVA1 parent were used as controls. Relative calcium (L/Lmax) levels were determined in the F1 crosses after elf18 (1 μM) treatment – showing that the cce5 phenotype was complemented when crossed with the bak1, serk4 and serk5 mutants and therefore not allelic to these genes. (n = 8–14 seedlings)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4279983&req=5

Fig3: CCE5is not allelic toBAK1,SERK4orSERK5. The cce5-1 allele was crossed to bak1-4 (left panel) or to serk4 or serk5 mutants (right panel). Crosses with Col-0 or the HVA1 parent were used as controls. Relative calcium (L/Lmax) levels were determined in the F1 crosses after elf18 (1 μM) treatment – showing that the cce5 phenotype was complemented when crossed with the bak1, serk4 and serk5 mutants and therefore not allelic to these genes. (n = 8–14 seedlings)
Mentions: BAK1 is the BRI1-associated receptor kinase shown to interact with FLS2, EFR and PEPR1/R2 receptors in a ligand-dependent manner [29]. To exclude that the cce5 mutants are weak alleles of BAK1 or the related SOMATIC EMBRYOGENESIS RELATED KINASE (SERK) members, cce5-1 was crossed to the mutants bak1-4, serk4-1 and serk5-1 [5]. Since the cce5 effect was most prominent for elf18 elicitation, we measured elf18-induced calcium fluxes in F1 seedlings, and observed that the cce5 phenotype was complemented (Figure 3). This result indicates that CCE5 is not allelic to BAK1, SERK4 or SERK5 and hence cce5 is mutated in a different gene.Figure 3

Bottom Line: They all show reduced calcium levels after elicitation with peptides representing bacteria-derived MAMPs (flg22 and elf18) and endogenous DAMP (AtPep1), but a normal response to chitin octamers.Validation with T-DNA mutants revealed that, besides PBL1, another RLCK, Botrytis-induced kinase 1 (BIK1), is also required for MAMP/DAMP-induced calcium elevations.Hence, PBL1 and BIK1 (but not two related RLCKs, PBS1 and PBL2) are required for MAMP/DAMP-induced calcium signaling.

View Article: PubMed Central - PubMed

Affiliation: Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Weinberg 3, Halle/Saale, D-06120, Germany. ranf@wzw.tum.de.

ABSTRACT

Background: Plant perception of conserved microbe-derived or damage-derived molecules (so-called microbe- or damage-associated molecular patterns, MAMPs or DAMPs, respectively) triggers cellular signaling cascades to initiate counteracting defence responses. Using MAMP-induced rise in cellular calcium levels as one of the earliest biochemical readouts, we initiated a genetic screen for components involved in early MAMP signaling in Arabidopsis thaliana.

Results: We characterized here the "changed calcium elevation 5" (cce5) mutant, where five allelic cce5 mutants were isolated. They all show reduced calcium levels after elicitation with peptides representing bacteria-derived MAMPs (flg22 and elf18) and endogenous DAMP (AtPep1), but a normal response to chitin octamers. Mapping, sequencing of the mutated locus and complementation studies revealed CCE5 to encode the receptor-like cytoplasmic kinase (RLCK), avrPphB sensitive 1-like 1 (PBL1). Kinase activities of PBL1 derived from three of the cce5 alleles are abrogated in vivo. Validation with T-DNA mutants revealed that, besides PBL1, another RLCK, Botrytis-induced kinase 1 (BIK1), is also required for MAMP/DAMP-induced calcium elevations.

Conclusions: Hence, PBL1 and BIK1 (but not two related RLCKs, PBS1 and PBL2) are required for MAMP/DAMP-induced calcium signaling. It remains to be investigated if the many other RLCKs encoded in the Arabidopsis genome affect early calcium signal transduction - perhaps in dependence on the type of MAMP/DAMP ligands. A future challenge would be to identify the substrates of these various RLCKs, in order to elucidate their signaling role between the receptor complexes at the plasma membrane and downstream cellular signaling components.

Show MeSH
Related in: MedlinePlus