Flagellin from an Incompatible Strain of Pseudomonas avenae Induces a Resistance Response in Cultured Rice Cells

Abstract

The host range of Pseudomonas avenae is wide among monocotyledonous plants, but individual strains can infect only one or a few host species. The resistance response of rice cells to pathogens has been previously shown to be induced by a rice-incompatible strain, N1141, but not by a rice-compatible strain, H8301. To clarify the molecular mechanism of the host specificity in P. avenae, a strain-specific antibody that was raised against N1141 cells and then absorbed with H8301 cells was prepared. When a cell extract of strain N1141 was separated by SDS-polyacrylamide gel electrophoresis and immunostained with the N1141 strain-specific antibody, only a flagellin protein was detected. Purified N1141 flagellin induced the hypersensitive cell death in cultured rice cells within 6 h of treatment, whereas the H8301 flagellin did not. The hypersensitive cell death could be blocked by pretreatment with anti-N1141 flagellin antibody. Furthermore, a flagellin-deficient N1141 strain lost not only the induction ability of hypersensitive cell death but also the expression ability of the EL2 gene, which is thought to be one of the defenserelated genes. These results demonstrated that the resistance response in cultured rice cells is induced by the flagellin existing in the incompatible strain of P. avenae but not in the flagellin of the compatible strain.

Molecular identification and characterization of the tomato flagellin receptor LeFLS2, an orthologue of Arabidopsis FLS2 exhibiting characteristically different perception specificities

“…During the past, several flagellin peptide variants have been discovered that do not elicit defense responses in A. thaliana Pfund et al 2004;Sun et al 2006). Furthermore, the so-called broad-species active flg22 peptide did not trigger defense responses in rice cell cultures, whereas they are responsive to a specific flagellin from the incompatible strain P. avenae Che et al 2000). It remains an open question what selective forces drive evolution of PAMP receptors such as the flagellin receptor into different directions.…”

Glycosylation Regulates Specific Induction of Rice Immune Responses by Acidovorax avenae Flagellin

“…To identify the specific recognition molecules that are related to the induction of these immune responses in cultured rice cells, a strain-specific antibody was raised against the avirulent strain and then absorbed with the virulent strain. The specific antibody detected the flagellin protein, which is structurally different between the virulent and avirulent strains of A. avenae (21). Flagellin purified from the avirulent N1141 strain induced rice immune responses, whereas flagellin purified from the virulent K1 strain did not induce these responses.…”

Glycan moiety of flagellin inAcidovorax avenaeK1 prevents the recognition by rice that causes the induction of immune responses

“…9,10,11,12 Among these PAMPs, flagellin, a main component of the bacterial flagellum, has been the most extensively studied in regards to the recognition mechanism and signal transduction. 13,14,15,16 We previously reported that flagellin from the rice avirulent N1141 strain of gram-negative phytopathogenic bacterium, Acidovorax avenae, induces PTI including H 2 O 2 generation, while flagellin from the rice virulent K1 strain of A. avenae does not induce. 14 16 Interestingly, mass spectrometry analysis using flagellins from the NDFlaA-KFlaA (K1 flagellin expression vector-possessing NDFlaA, N1141 flagellin deficient strain), KDFlaA-NFlaA (N1141 flagellin expression vector-possessing KDFlaA, K1 flagellin deficient strain) revealed that the molecular weight of each glycan chain in K1 flagellin is predicted to be 540, while the molecular weight of each glycan chain in N1141 flagellin is estimated to be 550.…”

“…13,14,15,16 We previously reported that flagellin from the rice avirulent N1141 strain of gram-negative phytopathogenic bacterium, Acidovorax avenae, induces PTI including H 2 O 2 generation, while flagellin from the rice virulent K1 strain of A. avenae does not induce. 14 16 Interestingly, mass spectrometry analysis using flagellins from the NDFlaA-KFlaA (K1 flagellin expression vector-possessing NDFlaA, N1141 flagellin deficient strain), KDFlaA-NFlaA (N1141 flagellin expression vector-possessing KDFlaA, K1 flagellin deficient strain) revealed that the molecular weight of each glycan chain in K1 flagellin is predicted to be 540, while the molecular weight of each glycan chain in N1141 flagellin is estimated to be 550. The K-type flagellin purified from the NDFlaA-KFlaA strain induced immune responses such as H 2 O 2 generation, while the flagellin from the KDFlaA-NFlaA strain did not induce H 2 O 2 to the same degree as the K1 wild-type flagellin.…”