Identifying Calmodulin and Calmodulin-like Protein Members in Canavalia rosea and Exploring Their Potential Roles in Abiotic Stress Tolerance

Calmodulins (CaMs) and calmodulin-like proteins (CMLs) belong to families of calcium-sensors that act as calcium ion (Ca²⁺) signal-decoding proteins and regulate downstream target proteins. As a tropical halophyte, Canavalia rosea shows great resistance to multiple abiotic stresses, including high salinity/alkalinity, extreme drought, heat, and intense sunlight. However, investigations of calcium ion signal transduction involved in the stress responses of C. rosea are limited. The CaM and CML gene families have been identified and characterized in many other plant species. Nevertheless, there is limited available information about these genes in C. rosea. In this study, a bioinformatic analysis, including the gene structures, conserved protein domains, phylogenetic relationships, chromosome distribution, and gene synteny, was comprehensively performed to identify and characterize CrCaMs and CrCMLs. A spatio-temporal expression assay in different organs and environmental conditions was then conducted using the RNA sequencing technique. Additionally, several CrCaM and CrCML members were then cloned and functionally characterized using the yeast heterogeneous expression system, and some of them were found to change the tolerance of yeast to heat, salt, alkalinity, and high osmotic stresses. The results of this study provide a foundation for understanding the possible roles of the CrCaM and CrCML genes, especially for halophyte C. rosea's natural ecological adaptability for its native habitats. This study also provides a theoretical basis for further study of the physiological and biochemical functions of plant CaMs and CMLs that are involved in tolerance to multiple abiotic stresses.