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IBR5 Modulates Temperature-Dependent, R Protein CHS3-Mediated Defense Responses in Arabidopsis
Jingyan Liu1, Haibian Yang1, Fei Bao1
1State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China.
The indole-3-butyric acid response 5 (IBR5) protein suppresses plant defense responses to cold. IBR5 interacts with the Toll and interleukin 1 receptor-nucleotide binding-leucine-rich repeat (TIR-NB-LRR) protein CHS3, protecting it and regulating plant immunity.
Area of Science:
- Plant molecular biology
- Plant immunity
- Stress responses
Background:
- Plant defense responses are activated by low temperatures.
- The chilling-sensitive mutant chs3-1 arises from an activated TIR-NB-LRR protein with a C-terminal LIM domain.
- CHS3 protein accumulation increases at chilling temperatures.
Purpose of the Study:
- To identify suppressors of the chs3-1 mutant.
- To investigate the role of IBR5 in plant defense and R-gene-mediated immunity.
Main Methods:
- Genetic screening for suppressors of chs3-1.
- Protein interaction studies.
- Analysis of defense gene expression and protein accumulation.
Main Results:
- The indole-3-butyric acid response 5 (IBR5) gene was identified as a suppressor of chs3-1.
- IBR5 encodes a dual-specificity protein phosphatase that inhibits CHS3 protein accumulation at chilling temperatures.
- IBR5 physically associates with CHS3, HSP90, and SGT1b, forming a complex that protects CHS3.
- IBR5 also positively regulates other resistance (R) genes, including SNC1, RPS4, and RPM1.
Conclusions:
- IBR5 plays a crucial role in suppressing chilling-activated defense responses.
- IBR5 is a key regulator of plant immunity, involved in the stability and function of multiple R proteins.
- This study reveals a novel mechanism for regulating plant defense through protein complex formation and R-gene modulation.
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