Genome-Wide Characterization and Expression Profile of the Jumonji-C Family Genes in × Reveal Their Potential Roles in Wood Formation.

The Jumonji C (JMJ-C) domain-containing gene family regulates epigenetic and developmental processes in plants. We identified 55 genes in × using HMM and BLASTp analyses. Chromosomal mapping revealed an asymmetric distribution with conserved synteny. Phylogenetic reconstruction revealed that genes segregate into five evolutionarily conserved subfamilies, exhibiting classification patterns identical to those of and . Synteny analysis indicated a closer relationship with than with . Motif and promoter analyses highlighted subfamily-specific features and diverse cis-elements, particularly light-responsive motifs. Expression profiling revealed tissue-specific patterns, with key genes enriched in roots, vascular tissues, and leaves. Developmental analysis in cambium and xylem identified four expression clusters related to wood formation. Co-expression analysis identified six key genes (, , , , and ) strongly associated with wood formation-related transcription factors. ChIP-qPCR analysis revealed that key genes co-expressed with genes were marked by H3K4me3 and H3K9me2 modifications. These findings provide insights into the evolutionary and functional roles of genes in poplar vascular development and wood formation.