Functional characterization of FvCAMTA1in salt stress response of Fraxinus velutina

The calmodulin-binding transcription activator (CAMTA) family plays crucial roles in calcium-mediated abiotic stress responses in plants. This study isolated and functionally characterized <i>FvCAMTA1</i>, a CAMTA gene from the salt-tolerant woody species <i>Fraxinus velutina</i>. Promoter analysis identified salt-responsive cis-elements, with a 157-bp core region sufficient for basal promoter activity and upstream sequences enhancing transcriptional activation under salt stress. <i>FvCAMTA1</i> was predominantly expressed in leaves and rapidly induced by NaCl treatment. The heterologous overexpression of <i>FvCAMTA1</i> in <i>Arabidopsis</i> significantly enhanced salt tolerance, resulting in higher germination rates, improved root elongation, and increased fresh weight, whereas the <i>camta5</i> mutant exhibited heightened sensitivity. Yeast two-hybrid screening identified 46 proteins interacting with <i>FvCAMTA1</i>, including <i>FvWRKY7</i> and <i>FvPP2C60</i>, interactions subsequently confirmed by bimolecular fluorescence complementation and luciferase complementation assays. Our findings demonstrate that <i>FvCAMTA1</i> acts as a positive regulator in the salt stress adaptation of woody plants through calcium signaling and transcriptional networks, providing a valuable candidate gene for molecular breeding of stress-resistant trees.