Objective B-box zinc finger proteins (BBX proteins) play a crucial role in defending plants against abiotic stress. Erianthus fulvus has excellent cold tolerance and serves as a valuable genetic resource for improving cold resistance in sugarcane. We identified and characterized members of the EfBBX gene family in E. fulvus, and explored their biological functions under cold stress. Method Members of the EfBBX gene family were identified from the whole genome of E. fulvus. Bioinformatics methods were employed to analyze their physicochemical properties, phylogenetic relationships, chromosomal localization, synteny analysis, gene structure, conserved domains, and promoter cis-elements. RT-qPCR experiments were conducted to examine the expression patterns of EfBBX family members under cold stress. Using the E. fulvus clonal line E2 as material, the coding sequences (CDS) of EfBBX4, EfBBX10, and EfBBX18 were cloned. The EfBBX18 gene was then transiently expressed in Nicotiana benthamiana. Result Nineteen members of the EfBBX gene family were identified in the whole genome of E. fulvus, classified into five subfamilies and unevenly distributed across six of its ten chromosomes. Subcellular localization predictions indicated that EfBBX proteins were primarily localized in the nucleus and chloroplasts. The promoter regions of the EfBBX gene family contain numerous elements associated with hormone, abiotic stress response, and light response pathways. RT-qPCR experiments confirmed that ten genes were induced by cold stress. The EfBBX4, EfBBX10, and EfBBX18 genes were successfully cloned, and transient expression of E. fulvusEfBBX18 in Nicotiana benthamiana enhanced the plant’s cold tolerance. Conclusion Nineteen EfBBX genes are identified from the E. fulvus genome, with ten genes inducible by cold stress. Three of these genes are successfully cloned, and transient expression of EfBBX18 in N. benthamiana enhances the plant’s tolerance to cold.
