Heterologous expression of <i>α‐AtCAH1</i> improves resistance to drought stress and increases tuber yield in potato ( <i>Solanum tuberosum</i> L.)

This study explores the role of α-AtCAH1, a carbonic anhydrase gene, in enhancing drought tolerance and tuber yield in potato plants. While carbonic anhydrases are known for their role in photosynthesis, their function in plant stress adaptation - particularly in regulating stomatal behaviour and abscisic acid (ABA) signalling - remains insufficiently explored. Transgenic potato plants were generated to constitutively express α-AtCAH1 under control of the 35S promoter. Drought stress was simulated under controlled laboratory conditions. Analyses included subcellular localization, stomatal aperture measurement, water loss assays, and quantification of ABA levels and expression of ABA-responsive genes, such as StRD29A and StOST1. Transgenic plants showed enhanced tolerance to simulated drought and increased tuber yield compared to the controls. α-AtCAH1 was mainly localized to chloroplasts in guard cells. These plants had reduced stomatal aperture and transpiration rates. Additionally, there was significant upregulation of ABA content and ABA-response genes, indicating an enhanced drought-responsive signalling mechanism. Heterologous expression of α-AtCAH1 improves drought tolerance in potato plants by promoting stomatal closure and reducing water loss, likely through activation of ABA signalling pathways. These findings suggest α-AtCAH1 is a promising genetic target for engineering drought-resistant crops with improved yield under water-limited conditions.