A <i>Bletilla striata</i> calcium-dependent protein kinase gene, <i>BsCDPK1</i>, enhances salinity stress tolerance in <i>Arabidopsis thaliana</i>

Calcium signaling plays a crucial role in stress sensing and alleviation in plants, with calcium-dependent protein kinases (CDPKs) acting as major sensors of Ca²⁺ flux. This study examined the function of BsCDPK1, a CDPK from the endangered medicinal orchid <i>Bletilla striata</i>, in mediating salt stress responses, a significant constraint on plant growth and productivity. Expression of the <i>BsCDPK1</i> gene was upregulated by salt stress and abscisic acid (ABA). Transgenic plants expressing <i>BsCDPK1</i> displayed salt insensitivity, as evidenced by seed germination, cotyledon greening, and relative root growth under high-salt conditions. Constitutive expression of <i>BsCDPK1</i> in <i>Arabidopsis</i> upregulated <i>AtMYB2</i> and the stress-response gene <i>AtDREB2A</i>. These findings highlight BsCDPK1’s role in the plant salt stress response, which is significant for conserving <i>Bletilla striata</i> understanding the plant calcium signaling mechanism, and potentially enhancing crop salt tolerance.