PcLBD16 mediates cell wall remodeling involved in the transcriptional regulatory mechanism underlying adventitious root formation in Prunus cerasifera

The difficulty in forming adventitious root (AR) in plums makes it challenging to achieve uniform high–quality rootstocks through asexual propagation. This not only hinders the standardized production of modern agriculture but also indirectly restricts the stability of tree vigor after grafting, ultimately becoming a key factor affecting the improvement of fruit quality and yield. Understanding the mechanism of AR formation in Myrobalan plum (Prunus cerasifera) is fundamental for efficient clonal propagation of rootstocks. This study investigated the effects of 1 g · L⁻¹ IBA on inducing AR formation in Prunus cerasifera, delineated the developmental trajectory of root primordia and the anatomical basis of AR formation through microscopic observations, and elucidated the key biological processes and genes involved in AR formation using combined transcriptome analysis. The results demonstrate that exogenous IBA application significantly promotes AR formation in P. cerasifera, with root primordia differentiating around day 6 post–induction and ARs emerging through the cortex around day 10. During AR formation, differentially expressed genes were significantly enriched in pathways related to IAA signal transduction, DNA transcriptional regulation, and cell wall component–related pathways. Gene expression and transcriptional regulatory network analyses identified PcLBD16 as a key transcription factor regulating AR formation, with its expression increasing dramatically by approximately 240–fold during the early induction phase and exhibiting high connectivity within the network. Yeast one–hybrid and dual–luciferase assays confirmed that PcLBD16 positively regulates the expression of genes encoding cellulose hydrolases (PcBGLU, PcEGL) and auxin–responsive (PcIAA, PcGH3). Overexpression of PcLBD16 in tobacco (Nicotiana benthamiana) significantly promoted tracheary element differentiation in vascular tissues, thereby enhancing AR formation. This study reveals the molecular mechanism whereby IBA activates PcLBD16 expression, which in turn regulates cell wall remodeling to promote AR growth. These findings not only provide a foundation for the efficient induction of AR formation and asexual propagation of rootstocks, but also provide valuable genetic resources for genetic–engineering–based creation and improvement of stone–fruit rootstocks.