Heterologous Expression of Potato StCML19 Enhances Drought Tolerance in Transgenic Arabidopsis

Calmodulin-like proteins (CMLs) serve as core components in plant calcium signal transduction pathways, and they extensively modulate plant growth, development, and adaptive responses to various abiotic stresses. In this study, we cloned the StCML19 gene from potato and generated stable transgenic Arabidopsis thaliana lines constitutively expressing this gene to investigate its functional role under drought stress. Transcriptome analysis revealed that StCML19 was up-regulated under drought conditions. Phenotypic assays showed that overexpressing StCML19 notably increased the seed germination rate and root length of transgenic Arabidopsis under mannitol-induced osmotic stress, and greatly improved the plant survival rate under severe soil drought stress. Physiological analysis showed that when put under drought stress, transgenic plants had higher proline content, better SOD, CAT, and POD activities, and significantly less malondialdehyde (MDA) accumulation than wild-type plants. In addition, overexpression of StCML19 led to greater plant sensitivity to exogenous ABA, with inhibited root growth and delayed seed germination as indicators. Conclusively, this study is the first to make sense of the biological function of potato StCML19 in the drought stress response and views StCML19 as a promising candidate gene for the genetic improvement of drought-tolerant potato varieties.