Fruit respiration: putting alternative pathways into perspective.

Area of Science:

• Plant Physiology
• Biochemistry
• Molecular Biology

Background:

• Fruit respiration research has evolved from ecophysiology to molecular mechanisms.
• Mitochondrial Alternative Respiratory Pathways (ARPs) play key roles in fruit growth and ripening.
• Understanding climacteric vs. nonclimacteric fruit distinctions is enhanced by insights into ARPs.

Purpose of the Study:

• To review the functional relevance and regulation of ARPs in fruit.
• To explore the roles of alternative oxidase, uncoupling proteins, and NDIIs.
• To highlight metabolic flexibility, energy balance, and redox homeostasis in fruits.

Main Methods:

• Literature review focusing on recent advancements in fruit respiration.
• Analysis of the roles of specific ARP components (AOX, UCPs, NDIIs).
• Discussion of metabolic features like CO2 refixation and organic acid metabolism.

Main Results:

• ARPs are central to metabolic flexibility, energy balance, and redox homeostasis in fruits.
• Fruit-specific metabolic pathways (C4/CAM-like) and tissue heterogeneity influence respiration.
• Interactions between respiration, ethylene, and mitochondrial retrograde signaling are critical for ripening.

Conclusions:

• ARPs are vital for fruit quality, stress resilience, and nutritional value.
• Targeting ARPs presents novel strategies for postharvest and metabolic engineering.
• Further research is needed on in vivo flux, energy profiling, and underexplored ARP components.