Identification and Characterization of the Efbzip Gene Family in Erianthus fulvus and Exploration of Functional Genes Involved in Sucrose Metabolism

<b>Background/Objectives</b>: Sugarcane (<i>Saccharum</i> spp.) is a major global sugar crop, and improving sucrose accumulation is critical for industry and bioenergy. Due to its high Brix content, <i>Erianthus fulvus</i> (<i>E. fulvus</i>) 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. <b>Methods</b>: Through bioinformatics methods, <i>Efbzip</i> gene family members were systematically identified within the genome of <i>E. fulvus</i>. 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. <b>Results</b>: Seventy-nine <i>Efbzip</i> 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 <i>Efbzip</i> proteins were hydrophilic and nuclear-localized. Cis-regulatory element analysis suggested <i>Efbzip</i> proteins regulate sucrose metabolism through hormone and light-responsive pathways. Segmental duplication primarily drove <i>Efbzip</i> gene family expansion. qRT-PCR showed predominant expression in stems and leaves, with subgroup-specific patterns. Nuclear localization of <i>Efbzip52</i> was confirmed. Transient overexpression of <i>Efbzip52</i>, <i>Efbzip61</i>, and <i>Efbzip64</i> significantly increased sucrose content in tobacco leaves, with highly statistically significant (<i>p</i> < 0.0001). <b>Conclusions</b>: In this study, the <i>Efbzip</i> gene family of <i>E. fulvus</i> 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.