Abstract：Calcium-dependent protein kinases (CDPKs or CPKs) function as Ca2+ sensors and effectors to directly translate Ca2+ signals into downstream phosphorylation signals. CDPKs are involved in plant growth and developmental processes, as well as responses to abiotic and biotic stresses. However, little information is available about the CDPK family in Saccharum plants. In this study, based on the published Saccharum spontaneum genome data, the CDPK gene family members of S. spontaneum were identified by bioinformatics methods, and a total of 90 CDPKs were identified, whose physical and chemical parameters, chromosomal locations, gene duplication, phylogenetic relationships, evolutionary characteristics, gene structure, and motif distribution were analyzed. Syntenic analysis showed that consensuses in CDPKs might have existed before the species divergence between S. spontaneum and Oryza sativa . The selection pressure analysis showed that CDPK genes in S. spontaneum were positively selected in the process of evolution and might play important roles in the evolution of plants. Transcriptome analysis showed that most SsCDPKs exhibited different expression levels in different tissues and developmental stages. In addition, many SsCDPKs in sugarcane hybrid variety Yuetang 55 (YT55) exhibited different expression profile under low-potassium and low-nitrogen treatments. The diverse expression of SsCDPKs suggested potential important function of SsCDPKs in regulating the development and responses to low-potassium and low-nitrogen stresses of Saccharum plants. This study provides a reference for further analysis of roles of Saccharum CDPK genes in the development and responses to nutrition stresses.
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