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 beta carbonic anhydrase (beta CA) gene expression levels and drought stress severity. For this purpose, the expression levels of six beta CA genes in the roots and leaves of Arabidopsis thaliana were in-vestigated 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 beta CA gene expression levels and CA enzyme activity increased in the leaf under mild drought conditions; however, the expression levels (except for beta CA-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 beta CA 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 beta CA expression level. The results indicated that beta CA genes may play important roles, especially in the onset of drought stress in A. thaliana. When the findings were evaluated together, beta CA genes may be considered to be important candidate genes for increasing or maintaining photosynthetic yield of C3 plants under drought stress conditions.