Dataset Information

RaxM regulates the AvrXa21 (RaxX)-mediated immune response.

ABSTRACT: Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease, which causes a reduction in rice production. The interaction between Xoo and rice is a model for the study of the gene-for-gene hypothesis, in which a resistance (R) gene encoding a product interacts with an effector molecule encoded by a corresponding bacterial avirulence (avr) gene. Rice XA21 functions as a plant innate immune receptor (R protein) and recognizes the avirulence protein (RaxX) of Xoo to induce the immune response and cope with pathogen attack. The sulphuration of RaxX by the tyrosine sulphotransferase RaxST is essential to its activity. The expression of raxST is regulated by the RaxH/RaxR and phoP/phoQ two-component systems. However, the regulation of raxX expression remains unclear. Here, we showed that a gene (raxM) encodes a small protein, which functions as a regulator of raxX expression. raxX and raxM are located upstream of raxST. Transcriptional analysis indicates that raxX and raxM are separately transcribed and the promoter of raxX is located at the raxM coding region. The RaxM protein regulates its own and raxX expression, and is required for the XA21-mediated immunity response. Therefore, we identified a regulator of raxX expression and of the Xoo-rice interaction. Our findings suggest that RaxX is not only regulated at the post-translational level, but also at the transcriptional level.

SUBMITTER: Xu C

PROVIDER: S-EPMC6638069 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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RaxM regulates the AvrXa21 (RaxX)-mediated immune response.

Xu Chunli C Wang Yaxin Y Liu Shiyao S Xie Qingbiao Q He Na N Shi Chenyi C Niu Xiaolei X He Chaozu C Li Chunxia C Tao Jun J

Molecular plant pathology 20180904 11

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease, which causes a reduction in rice production. The interaction between Xoo and rice is a model for the study of the gene-for-gene hypothesis, in which a resistance (R) gene encoding a product interacts with an effector molecule encoded by a corresponding bacterial avirulence (avr) gene. Rice XA21 functions as a plant innate immune receptor (R protein) and recognizes the avirulence protein (RaxX) of Xoo to ind ...[more]

PMID: 30011129

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Project description:BackgroundPlants are continuously challenged with biotic stress from environmental pathogens, and precise regulation of defense responses is critical for plant survival. Defense systems require considerable amounts of energy and resources, impairing plant growth, and plant hormones controlling transcriptional regulation play essential roles in establishing the appropriate balance between defense response to pathogens and growth. Chromatin regulators modulating gene transcription are broadly involved in regulating stress-responsive genes. However, which chromatin factors are involved in coordinating hormone signaling and immune responses in plants, and their functional mechanisms, remains unclear. Here, we identified a role of bromodomain-containing protein GTE4 in negatively regulating defense responses in Arabidopsis thaliana.ResultsGTE4 mainly functions as activator of gene expression upon infection with Pseudomonas syringe. Genome-wide profiling of GTE4 occupancy shows that GTE4 tends to bind to active genes, including ribosome biogenesis related genes and maintains their high expression levels during pathogen infection. However, GTE4 is also able to repress gene expression. GTE4 binds to and represses jasmonate biosynthesis gene OPR3. Disruption of GTE4 results in overaccumulation of jasmonic acid (JA) and enhanced JA-responsive gene expression. Unexpectedly, over-accumulated JA content in gte4 mutant is coupled with downregulation of JA-mediated immune defense genes and upregulation of salicylic acid (SA)-mediated immune defense genes, and enhanced resistance to Pseudomonas, likely through a noncanonical pathway.ConclusionsOverall, we identified a new role of the chromatin factor GTE4 as negative regulator of plant immune response through inhibition of JA biosynthesis, which in turn noncanonically activates the defense system against Pseudomonas. These findings provide new knowledge of chromatic regulation of plant hormone signaling during defense responses.

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RaxM regulates the AvrXa21 (RaxX)-mediated immune response.

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RaxM regulates the AvrXa21 (RaxX)-mediated immune response.

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