Manipulating stomatal density in Wheat : Differential impacts on photosynthesis and blue light responses across leaf surfaces

Mengjie Fan, Delfi Dorussen, Hussein Gherli, and Tracy Lawson
School of Life Sciences, University of Essex, Colchester, CO4 3SQ, United Kingdom.

Stomatal pores on leaf surfaces are vital for regulating gas exchange and water vapor loss in plants. This study explores the impact of reduced stomatal density on photosynthesis and blue light responses in bread wheat (Triticum aestivum L.) using transgenic lines overexpressing the EPF1 gene. Blue light, which triggers more efficient stomatal opening than red light, can also increase water loss without proportional carbon assimilation, affecting water use efficiency. Our findings suggest that reduced stomatal density influences overall photosynthetic rates and enhances the stomatal response to blue light, particularly on the abaxial leaf surface, hinting at a compensatory mechanism optimizing CO2 uptake. The transgenic lines also demonstrated improved water use efficiency under blue light. These observations underscore the adaptive capacity of wheat to fluctuating light environments through differential stomatal responses on adaxial and abaxial leaf surfaces. Moreover, our study highlights the successful enhancement of water use efficiency in transgenic wheat with targeted genetic manipulation of stomatal density. These findings emphasize the potential importance of stomatal behaviour under different light conditions in optimizing water usage and maintain photosynthetic performance in crop plants.