Oxylipins From Different Pathways Trigger Mitochondrial Stress Signaling Through Respiratory Complex III

Area of Science:

• Plant Biology
• Mitochondrial Physiology
• Biochemistry

Background:

• Plant oxylipins are fatty acid-derived signaling molecules involved in stress responses and development.
• The 9-lipoxygenase (9-LOX) pathway oxylipins, like 9(S)-hydroxy-10,12,15-octadecatrienoic acid (9-HOT) and 9-KOT, are known to induce oxidative stress and affect root growth.
• The precise cellular targets and signaling mechanisms of oxylipins, particularly their link to mitochondria, remain largely unknown.

Purpose of the Study:

• To investigate the role of mitochondria in plant oxylipin signaling pathways.
• To identify specific mitochondrial targets and cellular processes affected by 9-LOX pathway oxylipins.
• To elucidate the connection between oxylipin signaling, mitochondrial function, and reactive oxygen species (ROS) production.

Main Methods:

• Generation and analysis of Arabidopsis thaliana mutants (noxy) with impaired sensitivity to 9-LOX oxylipins.
• Phenotypic characterization of noxy mutants, including assessment of mitochondrial morphology and respiration rates.
• Application of oxylipins and mitochondrial inhibitors (e.g., Antimycin A) to study plant responses and gene expression.

Main Results:

• noxy mutants exhibited mitochondrial aggregation, reduced respiration, and resistance to Antimycin A, suggesting a link between oxylipin signaling and mitochondrial stress.
• 9-HOT and 9-KOT protected plants against mitochondrial stress and modulated root growth reduction in combination with complex III inhibitors.
• Oxylipins primarily enhanced ROS responses and amplified the expression of ROS-related genes, indicating activation of retrograde signaling.

Conclusions:

• Mitochondrial complex III acts as a central hub for signaling by various oxylipin pathways.
• Downstream reactive oxygen species (ROS) responses are key components of oxylipin function in plants.
• This study reveals a novel signaling pathway involving oxylipins, mitochondria, and ROS, impacting plant development and stress responses.