LAUSR

Homeodomain-leucine zipper (HD-Zip) proteins are plant-specific transcription factors that play important roles in different biological processes, especially leaf development. However, no studies to date have identified the HD-Zip genes in Liriodendron chinense nor characterized their functions. We identified the HD-Zip genes in L. chinense by analyzing the phylogeny, chromosomal location, structure, conserved motif, cis-regulatory elements, synteny, post-transcriptional regulation, and expression patterns of these genes during leaf development. A total of 36 LcHD-Zip genes were identified and divided into four subfamilies (HD-Zip Ⅰ to Ⅳ). Synteny analysis revealed that segmental duplication was the main force driving the expansion of LcHD-Zip genes. These 36 LcHD-Zip genes exhibited 11 different expression patterns. Pattern 1, 2, 3, 4, 6, 7, 8, and 9 genes may play important roles in leaf development, such as leaf initiation, leaf polarity establishment, leaf shape development, phytohormone-mediated leaf growth, and leaf epidermal structure formation. Four HD-Zip Ⅲ genes were targeted by microRNAs (miRNAs), and the miR165/166a-HD-Zip regulatory module formed regulates leaf initiation and leaf polarity establishment. Overall, LcHD-Zip genes might play key roles in the leaf development of L. chinense. This work provides a foundation for the functional verification of the HD-Zip genes identified in this study.