Transcriptome Analysis of the CML Gene Family in Bletilla striata and Regulation of Militarine Synthesis Under Sodium Acetate and Salicylic Acid Treatments

Calmodulin-like proteins (CMLs) are essential for calcium signal transduction in plants, influencing growth, development, stress responses, and the regulation of medicinal secondary metabolites. Despite their importance, the roles of <i>CML</i> genes in <i>B. striata</i> have not been characterized. This study aimed to elucidate the composition and function of the <i>BsCML</i> gene family in <i>B. striata</i>, identifying 38 genes across eight subfamilies. Evolutionary analysis showed that <i>BsCML</i> genes are stable and conserved, while functional predictions indicated involvement in environmental stress response, hormone regulation, and circadian rhythms. Expression profiling revealed that <i>BsCML27</i> and <i>BsCML16</i> were highly expressed during callus culture, suggesting their involvement in growth and development. Notably, <i>BsCML32</i> and <i>BsCML37</i> exhibited bidirectional regulation of militarine synthesis under sodium acetate (NaAc) and salicylic acid (SA) treatments, with tissue-specific expression strongly correlated (<i>p</i> < 0.01) with metabolite accumulation. These findings highlight the significant roles of <i>BsCML</i> genes in stress response and secondary metabolite synthesis, providing a foundation for enhancing the medicinal quality of <i>B. striata</i>.