Eucommia ulmoides (E. ulmoides) is a significant national strategic resource in China. It is a natural high quality rubber resource, with great development potential. We found large differences in rooting ability during adventitious root (AR) formation in two E. ulmoides improved varieties. Therefore, we used two improved varieties of E. ulmoides, ‘Huazhong 6’ (H6, with rooting rate 85.3%) and ‘Huazhong 8’ (H8, with rooting rate 22.5%) to explore the cutting rooting mechanism. In this study, we mainly determined the morphological development process of E. ulmoides cutting rooting, and compared the rooting-related indexes of the two improved varieties, and the changes in physiological indexes closely related to rooting, which include endogenous hormones, oxidases and nutrients in the phloem of the basal stem. The results showed that indole–3–acetic acid (IAA), zeatin riboside (ZR), IAA/ZR and indoleacetic acid oxidase (IAAO) were the key factors that caused big differences in rooting ability between the two E. ulmoides improved varieties. The increase in endogenous hormone IAA content and IAA/ZR value were necessary for the formation of AR. The increase in IAA content was beneficial to AR formation. The activity of IAAO was significantly negatively correlated with the rooting ability of the E. ulmoides cuttings. The high IAAO activity of the H8 cuttings led to the consumption of IAA. Although the content of IAA increased, the rooting conditions were not reached. The accumulation of nutrients before rooting also has an important effect on rooting; it is easy for cuttings to root when the carbon–nitrogen ratio (C/N) value is high. This research provides an improved understanding of the cellular and physiological underpinnings of the AR process in woody plants. In addition, it provides a theoretical basis and foundation for subsequent research on E. ulmoides cuttage technology.

1-deoxy-D-xylulose-5-phosphate synthase (DXS) is the first key enzyme in the methylerythritol phosphate (MEP) pathway of plant terpenoid biosynthesis, and it plays a vital role in Eucommia ulmoides terpenoid biosynthesis. In this study, bioinformatics methods were used to comprehensively identify and analyze the expression pattern of the EuDXS gene family, aiming to provide a basis for further functional study of EuDXS genes. A total of four EuDXS gene family members were identified and named EuDXS1 to EuDXS4. The encoded proteins contained 625 to 713 amino acid residues, with molecular weight ranging from 67.98 kDa to 76.61 kDa. The theoretical isoelectric points varied from 6.79 to 8.69, aliphatic index was between 85.29 and 91.29. In silico subcellular localization prediction revealed that all EuDXS proteins were localized in chloroplasts. EuDXS gene members were categorized into three subfamilies, which were unevenly distributed on three chromosomes. The promoters of EuDXS genes contained various cis-acting elements related to stress response, phytohormone signaling, light response and growth regulation. Expression pattern analysis showed that EuDXS genes exhibited tissue-specific expression: EuDXS1 was highly expressed in stem, leaf and fruit, EuDXS2 was predominantly expressed in fruit. EuDXS1 and EuDXS2 exhibited high expression levels at the early developmental stage of fruits and leaves. In addition, EuDXS genes responded to salt and drought stress in varying degrees. Transient expression in tobacco revealed that EuDXS1 and EuDXS2 could increase carotenoid and total chlorophyll content. This study will provide important genetic resources for further exploration of EuDXS gene function and germplasm innovation in E. ulmoides.