Abstract

Background Calmodulin (CaM) plays an essential role in binding calcium ions and mediating the interpretation of Ca 2+  signals in plants under various stresses. However, the evolutionary relationship of CaM family proteins in  Saccharum  has not been elucidated. Objective To deduce and explore the evolution and function of  Saccharum  CaM family. Methods A total of 104 typical CaMs were obtained from  Saccharum spontaneum  and other 18 plant species. The molecular characteristics and evolution of those CaM proteins were analyzed. A typical  CaM  gene,  ScCaM1 , was subsequently cloned from sugarcane ( Saccharum  spp. hybrid). Its expression patterns in different tissues and under various abiotic stresses were assessed by quantitative real-time PCR. Then the green fluorescent protein was used to determine the subcellular localization of ScCaM1. Finally, the function of  ScCaM1  was evaluated via heterologous yeast expression systems. Results Three typical CaM members (SsCaM1, SsCaM2, and SsCaM3) were identified from the  S. spontaneum  genome database. CaMs were originated from the two last common ancestors before the origin of angiosperms. The number of CaM family members did not correlate to the genome size but correlated with allopolyploidization events. The  ScCaM1  was more highly expressed in buds and roots than in other tissues. The expression patterns of  ScCaM1  suggested that it was involved in responses to various abiotic stresses in sugarcane via different hormonal signaling pathways. Noteworthily, its expression levels appeared relatively stable during the cold exposure in the cold-tolerant variety but significantly suppressed in the cold-susceptible variety. Moreover, the recombinant yeast ( Pichia pastoris ) overexpressing  ScCaM1  grew better than the wild-type yeast strain under cold and oxidative stresses. It was revealed that the  ScCaM1  played a positive role in reactive oxygen species scavenging and conferred enhanced cold and oxidative stress