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Eucommia ulmoides Oliver (E. ulmoides) is rich in a variety of medicinally active compounds which have a very high economic value. Various types of explants (stem, stem with axillary bud, terminal bud, and leaves) were cultured on Murashige and Skoog (MS) medium with different types and concentrations of growth regulators. The present study found that the cultured stem explants induced callus. Terminal bud and the stem with axillary bud–cultured explants induced clustered regenerated plantlets. The terminal bud was designated as clustered regenerated plantlets I after culture, while the stem with axillary bud was labeled as clustered regenerated plantlets II after culture. The highest induction rate of clustered regenerated plantlets was 66.67% after culture on medium supplemented with 0.5 mg ּL−1 6-benzylaminopurine (6-BA) and 0.01 mg ּL−1 α-naphthaleneacetic acid (NAA). The highest induction rate of callus tissue was 80.66% following culture on medium containing 0.09 mg ּL−1 NAA and 0.5 mg ּL−1 6-BA. The medicinal active ingredients of clustered regenerated plantlets and callus tissue were compared with those in natural seedlings and demonstrated that there was little difference in the types of compounds between clustered regenerated plantlets and natural seedlings. The contents of phenylpropanoids, phenols, flavonoids, lignin, and iridoids in different induced tissues were determined and showed that the best material for obtaining lignin compounds was clustered regenerated plantlets induced by terminal bud, and the best material for obtaining phenylpropanoids, phenols, and iridoids was clustered regenerated plantlets induced by stems with axillary bud. The theoretical basis and technical support provided in this study are essential for the establishment of an asexual propagation system for E. ulmoides and the commercial regeneration of plants. Furthermore, in vitro culture can efficiently produce a significant amount of medicinally active components, thereby decreasing reliance on wild resources. Research on the variations of medicinal components in E. ulmoides not only offers a theoretical foundation but also supplies experimental materials for the development of novel drugs. [ABSTRACT FROM AUTHOR]

Eucommia ulmoides Oliver with rich active components, such as flavonoids, lignans, polysaccharides, is used as a medicinal plant. Unfortunately, its popularization and cultivation are limited due to its low-temperature sensitivity. In this study, we aimed to explore the effect of different doses of ultraviolet-B (UV-B) radiation (UV-1, UV-2, and UV-3) and low-temperature (LT) stress, both applied individually and in combination, on the photosynthetic properties, biochemical parameters, and the contents of salicylic acid in E. ulmoides plants. The results showed that UV-B radiation alone significantly reduced photosynthetic performance and soluble total sugar content, as well as causing increases in soluble protein, proline, and superoxide anion content and antioxidant activity including SOD, POD, CAT, total phenol, and total flavonoid content. The leaf thickness and photosynthetic parameters significantly increased, as well as a significant decrease in SOD activity and soluble sugar, proline, and superoxide anion content after 14 days of none-UV-B radiation exposure. UV-B combined with LT significantly improved photosynthetic properties, Chl content, and soluble sugar content but significantly decreased proline content. Principal component analysis showed that salicylic acid was the key factor in improving LT tolerance, and UV-2 radiation showed the best LT resistance. We aim to provide new ideas and a theoretical basis for the directional cultivation and LT stress tolerance research of E. ulmoides. Our findings demonstrate that the combined effect was more positively helpful in improving the ability to resist LT tolerance via the improvement of photosynthetic ability and the increase in soluble sugar and salicylic acid content in E. ulmoides. [ABSTRACT FROM AUTHOR]