Fast dehydration reduces bundle sheath conductance in C4 maize and sorghum.
Chandra Bellasio1,2,3,4, Hilary Stuart-Williams4, Graham D Farquhar4
1Laboratory of Theoretical and Applied Crop Ecophysiology, School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, D04V1W8, Ireland.
The New Phytologist
|October 26, 2024
Summary
Drought severely impacts C4 plant photosynthesis by reducing CO2 conductance between leaf cells. This disrupts essential metabolite exchange, hindering the plants
Area of Science:
- Plant Physiology
- Biochemistry
- Climate Change Adaptation
Background:
- Anthropogenic warming increases drought frequency, threatening global food security.
- C4 plants possess a CO2 concentrating mechanism enhancing water use efficiency and productivity in hot climates.
- Dehydration significantly reduces photosynthetic efficiency in C4 plants, necessitating investigation into underlying mechanisms.
Purpose of the Study:
- To investigate the physiological mechanisms responsible for the decline in C4 photosynthesis during rapid dehydration.
- To elucidate the role of intercellular CO2 conductance and metabolite exchange in C4 plant response to drought stress.
Main Methods:
- Conducted fast dehydration experiments on C4 leaves.
- Measured gas exchange, including water and CO2 fluxes and isotopic composition.
- Utilized a novel biochemical model and elasticity analysis for data interpretation.
Main Results:
- CO2 supply to mesophyll and bundle sheath cells remained stable during dehydration.
- A significant decrease in CO2 conductance at the bundle sheath-mesophyll interface was observed.
- Intercellular metabolite exchange slowed, impeding reducing power supply to the bundle sheath.
Conclusions:
- Reduced CO2 conductance at the bundle sheath-mesophyll interface is a key factor in C4 photosynthesis decline under dehydration.
- This impairment leads to phosphoglycerate accumulation and feedback inhibition of Rubisco.
- The rapid sensitivity of C4 photosynthesis to dehydration may significantly influence their competitive performance and drought resilience.
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