The Decrease of Leaf Dark Respiration during Water Stress Is Related to Leaf Non-Structural Carbohydrate Pool in...

Area of Science:

• Plant Physiology
• Plant Stress Physiology
• Plant Respiration

Background:

• Dark respiration (Rd) is crucial for plant biomass accumulation and physiological function, metabolizing significant photosynthesized carbon.
• Understanding Rd under severe water stress is limited, despite temperature and carbohydrate availability being key drivers.
• Water stress impacts both leaf temperature (via transpiration) and carbohydrate pools, the primary substrates for respiration.

Purpose of the Study:

• To investigate the effect of water shortage on leaf dark respiration (Rd) in grapevine.
• To identify the key factors modulating leaf Rd under varying water stress conditions.

Main Methods:

• Measurements of leaf dark respiration (Rd) in grapevine plants subjected to different levels of water stress.
• Correlation analysis between Rd, leaf temperature, and leaf soluble sugar content.

Main Results:

• Leaf dark respiration (Rd) declined significantly with increasing water shortage severity in grapevine.
• In well-watered vines, Rd was positively correlated with leaf temperature.
• In water-stressed vines, Rd showed a strong correlation with leaf soluble sugar content, indicating substrate limitation.

Conclusions:

• Decreased leaf non-structural carbohydrates under water stress limit dark respiration (Rd) in grapevine.
• The primary driver of Rd shifts from leaf temperature to carbohydrate availability as water stress intensifies.
• Water stress fundamentally alters the regulation of dark respiration in plants.