DGK5β-derived phosphatidic acid regulates ROS production in plant immunity by stabilizing NADPH oxidase

Area of Science:

• Plant Biology
• Molecular Plant Pathology
• Biochemistry

Background:

• Plant immunity relies on reactive oxygen species (ROS) for defense.
• Phosphatidic acid (PA) is known to regulate ROS production by interacting with respiratory burst oxidase homolog D (RBOHD).

Purpose of the Study:

• To investigate the influence of PA binding on RBOHD activity.
• To elucidate the mechanism of PA generation bound to RBOHD.
• To understand the role of diacylglycerol kinase 5 (DGK5) in PA production and plant immunity.

Main Methods:

• Analysis of PA binding effects on RBOHD protein stability and ROS production.
• Investigating chitin-induced ROS and PA production in diacylglycerol kinase 5 (DGK5) mutants.
• Complementation studies using DGK5 isoforms (DGK5α and DGK5β).
• Site-directed mutagenesis to analyze the role of DGK5β phosphorylation at S506.

Main Results:

• PA binding enhances RBOHD protein stability by preventing vacuolar degradation, leading to increased chitin-induced ROS production.
• Mutations in DGK5 impair chitin-induced PA and ROS production.
• DGK5β, but not DGK5α, complements the defects in PA and ROS production and restores resistance to Botrytis cinerea in dgk5-1 mutants.
• Phosphorylation of DGK5β at S506 is critical for its activation and PA production.

Conclusions:

• DGK5β-derived PA regulates ROS production by inhibiting RBOHD protein degradation, thereby enhancing plant immune responses.
• The interplay between PA and ROS is a key mechanism in plant immune signaling.
• DGK5β is a crucial regulator of plant immunity through PA-mediated control of RBOHD.