Genetic regulation of the short-term stomatal CO2 response in Arabidopsis thaliana

Abstract

Plants respond to various environmental stimuli, including elevated CO₂, by partially closing their stomatal pores. This partial closure reduces water loss through transpiration while allow-ing photosynthesis to continue. Understanding how plants regulate this response is important for improving water use efficiency, especially in the context of climate change. However, the signalling pathways that control stomatal closure in response to CO₂ are complex, and many components are still unknown. This study aimed to investigate the genetic basis of CO₂-induced stomatal closure in Arabidop-sis thaliana using a Multiparent Advanced Generation Inter-Cross (MAGIC) population based on 19 founder lines. Gas exchange measurements were taken in 206 RILs, and quantitative trait locus (QTL) mapping was used to identify the genome regions linked to stomatal response to elevated CO₂ and related traits. A significant QTL was found on chromosome 1 associated with the percentage reduction in stomatal conductance in response to elevated CO₂. Further analysis of the genes in this region revealed 15 potential candidates. Additionally, a QTL on the same chromosome was linked to the speed of the response when CO₂ concentrations increased from 420 to 800 ppm. This study provides a foundation for exploring these QTLs and candidate genes, with the po-tential to improve plant adaptation to increased CO₂ and enhance water-use efficiency in future climates.