Study on adventitious root induction and endogenous hormone dynamics during cutting propagation of Distylium chinense

Distylium chinense has strong ecological adaptability and high ornamental value, which should have broad application prospects in urban landscaping. However, its low cutting rooting rate and slow rooting speed, as well as limited varietal numbers, have hindered its promotion and application in landscape. This study aims to reveal the development characteristics of adventitious roots (AR) and the regulation mechanism of endogenous hormones during the cutting propagation. Through cutting propagation and paraffin section technology, combined with immunohistochemical localization and hormone quantitative analysis, the morphogenesis of cuttings and the dynamic changes of endogenous hormones were comprehensively analyzed. The study found that the development of AR experienced three stages: induction period, expression period and elongation period, and the root primordium originated from vascular cambium, phloem, cortex and callus. Indoleacetic acid (IAA) and abscisic acid (ABA) signals accumulated in different tissues with the development of AR. IAA content showed a trend of ' decrease-increase ', zeatin riboside (ZR) and gibberellin (GA₃) content showed a trend of ' decrease-increase-decrease ', while ABA content showed a trend of ' increase-decrease-increase ' in the treatment group, which was compared with the ' decrease-increase ' trend of the control group. These results not only indicate that the development process of AR is closely related to the temporal and spatial changes of endogenous hormones, but also provide a new theoretical basis for the cultivation of new varieties and industrial production of D. chinense.