Abstract
Background/Objectives: Sugarcane (Saccharum spp.) is a major global sugar crop, and improving sucrose accumulation is critical for industry and bioenergy. Due to its high Brix content, Erianthus fulvus (E. fulvus) is valuable for genetic improvement of sugarcane. The bZIP transcription factor family critically regulates plant sucrose metabolism, but its roles in sugarcane remain largely unexplored. Methods: Through bioinformatics methods, Efbzip gene family members were systematically identified within the genome of E. fulvus. Gene expression patterns in distinct plant tissues were examined by RNA-seq and quantitative real-time PCR (qRT-PCR). Furthermore, genes potentially involved in sucrose metabolism were screened using transient expression assays and subcellular localization studies conducted in tobacco. Results: Seventy-nine Efbzip genes were identified and classified into nine subgroups, showing uneven distribution across ten chromosomes. Among ten conserved motifs, Motif1 was most conserved. Subcellular localization and physicochemical analyses showed most Efbzip proteins were hydrophilic and nuclear-localized. Cis-regulatory element analysis suggested Efbzip proteins regulate sucrose metabolism through hormone and light-responsive pathways. Segmental duplication primarily drove Efbzip gene family expansion. qRT-PCR showed predominant expression in stems and leaves, with subgroup-specific patterns. Nuclear localization of Efbzip52 was confirmed. Transient overexpression of Efbzip52, Efbzip61, and Efbzip64 significantly increased sucrose content in tobacco leaves, with highly statistically significant (p < 0.0001). Conclusions: In this study, the Efbzip gene family of E. fulvus was systematically characterized for the first time. Key candidate genes potentially involved in sucrose metabolism were identified, providing potential targets for the genetic improvement of sugarcane.