Beta-carbonic anhydrase gene expression levels change depending on the drought severity in both the leaves and roots of Arabidopsis thaliana

: In this study, it was aimed to determine the relationship between β carbonic anhydrase (βCA) gene expression levels and drought stress severity. For this purpose, the expression levels of six βCA genes in the roots and leaves of Arabidopsis thaliana were investigated under mild, moderate, and severe drought conditions. In addition, changes in the biomass, leaf water content, photosynthetic efficiency, CA enzyme activity, free proline content, and lipid peroxidation were also determined. The results showed that all of the β CA gene expression levels and CA enzyme activity increased in the leaf under mild drought conditions; however, the expression levels (except for βCA-6) and enzyme activity decreased as the severity of drought increased. In the roots, the gene expression levels were very low compared to the leaves and all of the βCA gene expressions decreased under drought stress. Moreover, depending on the severity of the drought stress, the biomass, leaf water content, and photosynthetic efficiency decreased, while the content of proline and lipid peroxidation increased. A positive correlation was determined between the photosynthetic efficiency and high βCA expression level. The results indicated that βCA genes may play important roles, especially in the onset of drought stress in A. thaliana . When the findings were evaluated together, βCA genes may be considered to be important candidate genes for increasing or maintaining photosynthetic yield of C 3 plants under drought stress conditions.