Identification of the regulatory role of LBD transcription factors in the development of lateral roots of tree peony

Tree peony is an important ornamental horticultural crop and its root has medicinal value. The LBD genes, as plant-specific transcription factors (TFs), are essential for plant development and stress adaptation, especially for lateral organ formation, but their function in root development of tree peony remains poorly characterized. In this study, a comprehensive analysis of the LBD protein in Paeonia ostil was performed and 31 PoLBD genes were identified. The random distribution of 31 genes on 5 chromosomes revealed significant differences in their representativeness. They are divided into 7 subfamilies, and the genes in the same subfamily have similar structural characteristics, indicating functional correlation. The expression analysis revealed the spatiotemporal expression specificity and developmental pattern of LBD genes in roots, and PoLBD31 was selected for functional verification due to its high expression in lateral roots. The transcriptional regulatory network of PoLBD genes was further constructed, and the mechanism of PoARF5 regulating PoLBD31 involved in lateral root development in response to auxin signal was revealed. The study provided important insights into tree peony LBD proteins, and laid a foundation for its functional verification and genetic engineering application. • The expression and structural characteristics of PoLBDs were identified. • Overexpression of PoARF5 and PoLBD31 promoted lateral root development. • PoARF5 bound to PoLBD31 and promoted its transcription under auxin signals