Eucommia ulmoides Oliver (EUO), an economic tree grown specifically in China, is widely used in various fields. To satisfy the requirements of industrial development, superior varieties need to be selected for different uses. However, there is no unified standard for breeders to reference. In this study, leaf-related traits were classified by a probability grading method. The results indicated there were significant differences between different planting models for the studied traits, and the traits in the Arbor forest model showed more abundant variation. Compared with genotype, the planting model accounted for relatively bigger variance, indicating that the standard should be divided according to planting models. Furthermore, the optimum planting model for different traits would be obtained by analyzing the variation range. Association analyses were conducted among traits to select the crucial evaluation indexes. The indexes were divided into three grades in different planting models. The evaluation system on leaf-related traits of EUO germplasm was established preliminarily, which considered planting models and stability across years for the first time. It can be treated as a reference to identify and evaluate EUO germplasm resources. Additionally, the study served as an example for the classification of quantitative traits in other economically important perennial plants.
Eucommia ulmoides Oliver is a woody plant with great economic and medicinal value. Its dried bark has a long history of use as a traditional medicinal material in East Asia, which led to many glycosides, such as aucubin, geniposide, hyperoside, astragalin, and pinoresinol diglucoside, being recognized as pharmacologically active ingredients. Uridine diphosphate glycosyltransferases (UGTs) catalyze a glycosyl-transferring reaction from the donor molecule uridine-5′-diphosphate-glucose (UDPG) to the substrate, which plays an important role in many biological processes, such as plant growth and development, secondary metabolism, and environmental adaptation. In order to explore the biosynthetic pathways of glycosides in E. ulmoides, 91 putative EuUGT genes were identified throughout the complete genome of E. ulmoides through function annotation and an UDPGT domain search. Phylogenetic analysis categorized them into 14 groups. We also performed GO annotations on all the EuUGTs to gain insights into their functions in E. ulmoides. In addition, transcriptomic analysis indicated that most EuUGTs showed different expression patterns across diverse organs and various growing seasons. By protein–protein interaction predication, a biosynthetic routine of flavonoids and their glycosides was also proposed. Undoubtedly, these results will help in future research into the biosynthetic pathways of glycoside compounds in E. ulmoides.
Response surface methodology was utilized to optimize the microwave-assisted extraction of flavonoids from Eucommia ulmoides Oliver seed meal. In addition, the optimal processing conditions for the extraction of E. ulmoides seed meal flavonoids were as follows: a processing time of 30 min, a liquid to solid ratio of 54 to 1 (mL/g), an ethanol concentration of 77%, and a temperature of 69 °C. The total flavonoids extraction percentage was 0.6611%. Moreover, the total flavonoids extracted from E. ulmoides seed meal were good for scavenging diphenyl picryl hydrazinyl. The E. ulmoides seed meal total flavonoids exhibited an obvious dose-dependent inhibitory effect on α-glucosidase in the concentration range of 0.05 to 1.0 mg·mL−1. The IC50 value of the E. ulmoides seed meal flavonoids was slightly lower than the IC50 value of acarbose. According to the results of the xanthine oxidase inhibitory activity test, the IC50 value of the E. ulmoides seed meal flavonoids was higher than the IC50 value of allopurinol.