Two cowpea Rubisco activase isoforms for crop thermotolerance

Area of Science:

• Plant Biology
• Molecular Chaperones
• Crop Resilience

Background:

• Cowpea is crucial for sub-Saharan Africa but vulnerable to climate change.
• Rubisco activase (Rca) is vital for Rubisco function and crop heat tolerance.
• Rca's thermal sensitivity limits crop performance under heat stress.

Purpose of the Study:

• Identify and characterize Rubisco activase (Rca) isoforms in cowpea (Vigna unguiculata).
• Assess the impact of heatwaves on cowpea growth, Rubisco activity, and Rca isoform abundance.
• Evaluate the potential of specific Rca isoforms for enhancing crop thermotolerance.

Main Methods:

• In vitro characterization of four cowpea Rca isoforms (Rca1β, Rca8α, Rca10α, Rca10β).
• Investigated cowpea plant and leaf traits during a 5-day +10°C heatwave.
• Assessed Rubisco and Rca activity, and Rca isoform abundance in leaf extracts.

Main Results:

• Cowpea Rca10α and Rca10β exhibited higher thermal maxima and optima, with increased ATP hydrolysis and Rubisco reactivation rates.
• A +10°C heatwave caused mild effects on cowpea without water deficit, including increased leaf temperature and Rca10 expression.
• Rubisco activity and activation state slightly decreased, but the temperature response of Rubisco activation by Rca remained unaltered.

Conclusions:

• Cowpea Rca10α and Rca10β isoforms demonstrate superior thermal properties.
• These Rca isoforms offer a promising avenue for enhancing cowpea and other crop thermotolerance.
• Targeting Rca10 isoforms can improve crop adaptation to future heatwave conditions.