Systems Phytohormone Responses to Mitochondrial Proteotoxic Stress

Area of Science:

• Plant Biology
• Mitochondrial Biology
• Cellular Stress Response

Background:

• Mitochondrial function relies on dual genomes (nuclear and mitochondrial).
• Mitochondria are susceptible to proteotoxic stress from protein complex imbalances.
• The mitochondrial unfolded protein response (UPR^mt) is known in animals but not plants.

Purpose of the Study:

• To investigate the existence and mechanisms of UPR^mt in plants.
• To understand how mitonuclear protein imbalance affects plant growth.
• To identify signaling pathways involved in plant UPR^mt.

Main Methods:

• Induced mitonuclear protein imbalance in Arabidopsis using chemical and genetic methods.
• Monitored plant growth and development.
• Analyzed signaling pathways including MAPK and phytohormone signaling.

Main Results:

• Mitochondrial proteotoxic stress triggers a plant-specific UPR^mt.
• This stress impairs plant growth and development.
• The plant UPR^mt involves an oxidative burst, MAPK, and hormonal signaling (ethylene, auxin).
• Phytohormones act as plant mitokines.

Conclusions:

• Mitochondrial protein quality control pathways, including UPR^mt, are conserved in plants.
• Hormone signaling is crucial for regulating mitochondrial proteostasis in plants.