Genome-wide analysis of the CML gene family and its response to cold stress in Curcuma alismatifolia

Calmodulin-like (CML) transcription factors function as calcium (Ca²⁺) signal sensors and play a pivotal role in plant cold resistance. Although this gene family has been identified in various plant species, the characteristics of the CML gene family in Curcuma alismatifolia and its function under cold stress remain largely unknown. This study identified 202 CACML genes in the Curcuma alismatifolia genome, which were phylogenetically classified into four clades. Members within each clade shared conserved gene structures and motifs. Gene duplication analysis revealed that segmental duplication events (44 events) served as the primary driving force for the expansion of the CACML family. Most homologous gene pairs were subjected to strong purifying selection during evolution, while CACML86 underwent positive selection in both C. alismatifolia and A. viiosum. Promoter regions were enriched with cis-acting elements associated with growth and development, biotic/abiotic stress responses, and hormone responsiveness, suggesting diverse functional roles for CACML genes. Transcriptome analysis indicated that CACML140 regulates the cold stress response in Curcuma alismatifolia via the MAPK cascade signaling pathway. These findings enhance our understanding of CML-mediated cold stress responses in Curcuma alismatifolia and establish a framework for the systematic dissection of CML gene function and the regulatory network governing cold hardiness.