Genome-wide characterization and expression analysis of LBD transcription factors in var. : putative roles in tissue development and abiotic stress adaptation.

The plant-specific Lateral Organ Boundaries Domain (LBD) transcription factors (TFs) are critical regulators of the expression of genes related to tissue development and stress responses. Sour jujube ( var. ), a stress-tolerant rootstock for jujube cultivation, remains understudied in terms of its gene family. In this study, a genome-wide analysis of the sour jujube genome was performed and genes were identified. These genes were phylogenetically classified into two classes and six subgroups based on evolutionary relationships with and poplar. These genes were unevenly distributed across 11 chromosomes, with 15 segmental duplication events detected. Upstream TFs of s were predicted and grouped into six interactive networks, revealing that the functions of s may be enriched in stress response, hormone signaling, and tissue development. RNA-seq data demonstrated tissue-specific expression patterns of s, with limited genes highly expressed in fruit. The may regulate the development of flowers and white mature fruits, while and may be involved in lateral root formation. Analysis of the cis-acting elements, homology relationships and abiotic stress-induced expression levels suggested functional divergence: , and may contribute to extreme cold resistance, , , and may be associated with drought tolerance, and , and with salt stress adaptation. This study provides critical insights into the biological roles of s and lays a foundation for breeding sour jujube varieties with enhanced stress resilience.