Phosphate-deprivation and damage signalling by extracellular ATP

Area of Science:

• Plant immunity
• Plant signaling
• Nutrient sensing

Background:

• Phosphate deprivation negatively impacts plant productivity and immunity.
• Extracellular ATP (eATP) acts as a Damage-Associated Molecular Pattern (DAMP) signal, but its function may be compromised under phosphate-limited conditions due to reduced ATP synthesis and eATP salvage for nutrition.
• Phosphate-starved Arabidopsis roots retain the ability to sense eATP, suggesting receptor function remains intact, but downstream calcium (Ca2+) signaling is altered.

Purpose of the Study:

• To explore how DAMP signaling via eATP is affected by phosphate deprivation.
• To understand the mechanisms of eATP salvage and its role in immunity under phosphate stress.
• To investigate how Ca2+ signals are generated and how these pathways can be modulated to facilitate beneficial fungal root colonization for phosphate acquisition.

Main Methods:

• This study is a perspective/review, synthesizing existing research on eATP signaling, phosphate deprivation, and plant immunity.
• It discusses the salvage pathways for eATP and its impact on immune responses.
• It examines Ca2+ signal generation and potential strategies for overcoming signaling pathway limitations.

Main Results:

• Despite phosphate starvation, Arabidopsis roots maintain eATP perception, indicating robust receptor function.
• The downstream cytosolic free Ca2+ signature in response to eATP is impaired, suggesting modulation of signaling components.
• Endophytic fungi can colonize roots by down-regulating Ca2+ channels downstream of eATP receptors and inhibiting ROS accumulation, thereby hindering DAMP signaling.

Conclusions:

• Phosphate deprivation affects plant immunity by altering eATP-mediated DAMP signaling, specifically impairing Ca2+ signatures.
• Beneficial fungal symbionts can exploit these altered signaling pathways for successful root colonization.
• Fungal strategies, including Ca2+ channel and ROS modulation, can overcome plant immune responses to facilitate nutrient exchange.