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Specific missense alleles of the arabidopsis jasmonic acid co-receptor COI1 regulate innate immune receptor accumulation and function.

He Y, Chung EH, Hubert DA, Tornero P, Dangl JL - PLoS Genet. (2012)

Bottom Line: The first, also observed in coi1-1 allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB-LRR RPM1 protein in both rar1 and wild-type backgrounds.These results suggest that the coi1(rsp) proteins regulate NB-LRR protein accumulation independent of JA signaling.Together, our data demonstrate a role for COI1 in disease resistance independent of JA signaling and provide a molecular link between the JA and NB-LRR signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.

ABSTRACT
Plants utilize proteins containing nucleotide binding site (NB) and leucine-rich repeat (LRR) domains as intracellular innate immune receptors to recognize pathogens and initiate defense responses. Since mis-activation of defense responses can lead to tissue damage and even developmental arrest, proper regulation of NB-LRR protein signaling is critical. RAR1, SGT1, and HSP90 act as regulatory chaperones of pre-activation NB-LRR steady-state proteins. We extended our analysis of mutants derived from a rar1 suppressor screen and present two allelic rar1 suppressor (rsp) mutations of Arabidopsis COI1. Like all other coi1 mutations, coi1(rsp) missense mutations impair Jasmonic Acid (JA) signaling resulting in JA-insensitivity. However, unlike previously identified coi1 alleles, both coi1(rsp) alleles lack a male sterile phenotype. The coi1(rsp) mutants express two sets of disease resistance phenotypes. The first, also observed in coi1-1 allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB-LRR RPM1 protein in both rar1 and wild-type backgrounds. These enhanced disease resistance phenotypes depend on the JA signaling function of COI1. Additionally, the coi1(rsp) mutants showed a unique inability to properly regulate RPM1 accumulation and HR, exhibited increased RPM1 levels in rar1, and weakened RPM1-mediated HR in RAR1. Importantly, there was no change in the steady-state levels or HR function of RPM1 in coi1-1. These results suggest that the coi1(rsp) proteins regulate NB-LRR protein accumulation independent of JA signaling. Based on the phenotypic similarities and genetic interactions among coi1(rsp), sgt1b, and hsp90.2(rsp) mutants, our data suggest that COI1 affects NB-LRR accumulation via two NB-LRR co-chaperones, SGT1b and HSP90. Together, our data demonstrate a role for COI1 in disease resistance independent of JA signaling and provide a molecular link between the JA and NB-LRR signaling pathways.

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coi1rsp mutants suppress rar1 phenotypes and are not  allele.(A–B) Bacterial growth analysis of (A) Pto DC3000(avrRpm1) and (B) Pto DC3000(EV). Bacteria were hand-infiltrated into leaves of each indicated genotype and counted at day 0 and day 3. Error bars represent 2× SE. Pairwise comparisons for all means for bacterial growth on day 3 were performed with One-Way ANOVA test followed by Tukey-Kramer HSD at 95% confidence limits. (C) Western blot analysis of RPM1-myc and COI1 levels in the indicated genotypes. RuBisCo levels stained by Coomassie Brilliant Blue serve as loading controls. The pathogen growth assays were performed independently three times with similar results. The western blots were performed independently two times with similar results. Both RPM1-myc and COI1 blots used the same protein samples.
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pgen-1003018-g003: coi1rsp mutants suppress rar1 phenotypes and are not allele.(A–B) Bacterial growth analysis of (A) Pto DC3000(avrRpm1) and (B) Pto DC3000(EV). Bacteria were hand-infiltrated into leaves of each indicated genotype and counted at day 0 and day 3. Error bars represent 2× SE. Pairwise comparisons for all means for bacterial growth on day 3 were performed with One-Way ANOVA test followed by Tukey-Kramer HSD at 95% confidence limits. (C) Western blot analysis of RPM1-myc and COI1 levels in the indicated genotypes. RuBisCo levels stained by Coomassie Brilliant Blue serve as loading controls. The pathogen growth assays were performed independently three times with similar results. The western blots were performed independently two times with similar results. Both RPM1-myc and COI1 blots used the same protein samples.

Mentions: hsp90.2rsp alleles isolated from our rar1 suppressor screen recover all known defective NB–LRR functions in a rar1 mutant background [21]. However, a previously published rar1 suppressor mutant, sgt1b, only affected a limited number of NB–LRR protein functions [25]. We therefore tested both coi1rsp alleles to determine whether they have any NB–LRR specificity in their suppression of rar1. The coi1rsp alleles partially suppress rar1 for RPS5 and RPM1 functions, and fully suppress rar1 for RPS2 function (Figure 2, Figure S2A and S2B, Figure 3A).


Specific missense alleles of the arabidopsis jasmonic acid co-receptor COI1 regulate innate immune receptor accumulation and function.

He Y, Chung EH, Hubert DA, Tornero P, Dangl JL - PLoS Genet. (2012)

coi1rsp mutants suppress rar1 phenotypes and are not  allele.(A–B) Bacterial growth analysis of (A) Pto DC3000(avrRpm1) and (B) Pto DC3000(EV). Bacteria were hand-infiltrated into leaves of each indicated genotype and counted at day 0 and day 3. Error bars represent 2× SE. Pairwise comparisons for all means for bacterial growth on day 3 were performed with One-Way ANOVA test followed by Tukey-Kramer HSD at 95% confidence limits. (C) Western blot analysis of RPM1-myc and COI1 levels in the indicated genotypes. RuBisCo levels stained by Coomassie Brilliant Blue serve as loading controls. The pathogen growth assays were performed independently three times with similar results. The western blots were performed independently two times with similar results. Both RPM1-myc and COI1 blots used the same protein samples.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3475666&req=5

pgen-1003018-g003: coi1rsp mutants suppress rar1 phenotypes and are not allele.(A–B) Bacterial growth analysis of (A) Pto DC3000(avrRpm1) and (B) Pto DC3000(EV). Bacteria were hand-infiltrated into leaves of each indicated genotype and counted at day 0 and day 3. Error bars represent 2× SE. Pairwise comparisons for all means for bacterial growth on day 3 were performed with One-Way ANOVA test followed by Tukey-Kramer HSD at 95% confidence limits. (C) Western blot analysis of RPM1-myc and COI1 levels in the indicated genotypes. RuBisCo levels stained by Coomassie Brilliant Blue serve as loading controls. The pathogen growth assays were performed independently three times with similar results. The western blots were performed independently two times with similar results. Both RPM1-myc and COI1 blots used the same protein samples.
Mentions: hsp90.2rsp alleles isolated from our rar1 suppressor screen recover all known defective NB–LRR functions in a rar1 mutant background [21]. However, a previously published rar1 suppressor mutant, sgt1b, only affected a limited number of NB–LRR protein functions [25]. We therefore tested both coi1rsp alleles to determine whether they have any NB–LRR specificity in their suppression of rar1. The coi1rsp alleles partially suppress rar1 for RPS5 and RPM1 functions, and fully suppress rar1 for RPS2 function (Figure 2, Figure S2A and S2B, Figure 3A).

Bottom Line: The first, also observed in coi1-1 allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB-LRR RPM1 protein in both rar1 and wild-type backgrounds.These results suggest that the coi1(rsp) proteins regulate NB-LRR protein accumulation independent of JA signaling.Together, our data demonstrate a role for COI1 in disease resistance independent of JA signaling and provide a molecular link between the JA and NB-LRR signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.

ABSTRACT
Plants utilize proteins containing nucleotide binding site (NB) and leucine-rich repeat (LRR) domains as intracellular innate immune receptors to recognize pathogens and initiate defense responses. Since mis-activation of defense responses can lead to tissue damage and even developmental arrest, proper regulation of NB-LRR protein signaling is critical. RAR1, SGT1, and HSP90 act as regulatory chaperones of pre-activation NB-LRR steady-state proteins. We extended our analysis of mutants derived from a rar1 suppressor screen and present two allelic rar1 suppressor (rsp) mutations of Arabidopsis COI1. Like all other coi1 mutations, coi1(rsp) missense mutations impair Jasmonic Acid (JA) signaling resulting in JA-insensitivity. However, unlike previously identified coi1 alleles, both coi1(rsp) alleles lack a male sterile phenotype. The coi1(rsp) mutants express two sets of disease resistance phenotypes. The first, also observed in coi1-1 allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB-LRR RPM1 protein in both rar1 and wild-type backgrounds. These enhanced disease resistance phenotypes depend on the JA signaling function of COI1. Additionally, the coi1(rsp) mutants showed a unique inability to properly regulate RPM1 accumulation and HR, exhibited increased RPM1 levels in rar1, and weakened RPM1-mediated HR in RAR1. Importantly, there was no change in the steady-state levels or HR function of RPM1 in coi1-1. These results suggest that the coi1(rsp) proteins regulate NB-LRR protein accumulation independent of JA signaling. Based on the phenotypic similarities and genetic interactions among coi1(rsp), sgt1b, and hsp90.2(rsp) mutants, our data suggest that COI1 affects NB-LRR accumulation via two NB-LRR co-chaperones, SGT1b and HSP90. Together, our data demonstrate a role for COI1 in disease resistance independent of JA signaling and provide a molecular link between the JA and NB-LRR signaling pathways.

Show MeSH
Related in: MedlinePlus