Genome-Wide Identification and Expression Analysis of LBD Gene Family in Neolamarckia cadamba

Lateral Organ Boundaries Domain (LBD) proteins are plant-specific transcription factors characterized by a typical N-terminal LOB domain and are critical for plant growth, development, and stress response. Currently, LBD genes have been investigated in various plant species, but they have yet to be identified in Neolamarckia cadamba, known as a ‘miracle tree’ for its fast growth and acknowledged for its potential medicinal value in tropical and subtropical areas of Asia. In this study, a total of 65 NcLBD members were identified in N. cadamba by whole-genome bioinformatics analysis. Phylogenetic analysis revealed their classification into two clades with seven distinct groups, and their uneven distribution across 18 chromosomes, along with 6 tandem repeats and 58 segmental duplications. Furthermore, enrichment analysis of transcription factor binding motifs within NcLBD promoters identified the MYB-related and WRKY families exhibited the most significant enrichment in the NcLBD promoter. Protein interaction network analysis revealed potential interactions among NcLBD proteins, as well as their interactions with various transcription factors. RNA-seq and qRT-PCR analyses of NcLBDs transcript levels showed distinct expression patterns both across various tissues and under different hormone and abiotic stress conditions. Specifically, NcLBD3, NcLBD37, and NcLBD47 were highly expressed in vascular cells and induced by abiotic stress, including cold, drought, and salt, suggesting their significant role in the processes. In summary, our genome-wide analysis comprehensively identified and characterized LBD gene family in N. cadamba, laying a solid foundation for further elucidating the biological functions of NcLBD genes.