Comprehensive analysis of the LiCPKs in Lagerstroemia indica for insights into evolution and regulatory roles in flower maturation and bud-to-branch development

Calcium ions (Ca2+) serve as crucial second messengers in a wide range of developmental and stress-related processes in plants. Calcium-dependent protein kinases (CPKs) play essential roles in Ca2+ signal transduction, regulating essential stress responses. In this study, we identified 38 LiCPKs from the Lagerstroemia indica L. genome. Phylogenetic tree classified these CPKs into five distinct groups-CPKI, CPKII, CPKIII, CPKIV, and CRK, indicating a closer genetic relationship between crape myrtle and Arabidopsis, compared to rice. Gene duplication analysis revealed that segmental duplication is the primary mechanism driving the expansion of LiCPKs. Weighted gene co-expression network analysis (WGCNA) highlighted the involvement of LiCPKs in developmental processes, including flower pigmentation, particularly during red flower maturation. Additionally, WGCNA revealed that several LiCPKs are involved in regulating developmental transitions from bud initiation to branch formation. These findings offer meaningful insights into the evolutionary history, structural diversity, and functional significance of LiCPKs, contributing to a deeper understanding of their roles in plant development and adaptation.