Medicinal Plant Research 2025, Vol.15, No.3, 119-128 http://hortherbpublisher.com/index.php/mpr 125 a complete tissue culture technology system for tetraploid A. roxburghii from proliferation to transplantation, providing a new approach for the protection of endangered resources, and laying a foundation for its medicinal and industrial utilization. 6.2 The effect of exogenous putretic amine on the antioxidant activity of A. roxburghii A. roxburghii is rich in active substances such as polysaccharides, flavonoids and terpenoids, but its adaptability is relatively weak and it is extremely sensitive to environmental stress, especially drought. Drought conditions can lead to a large accumulation of reactive oxygen species (ROS) in the body, thereby triggering membrane lipid peroxidation, damaging cell structure, and weakening plant growth and medicinal material quality (Cui et al., 2023; Sun et al., 2023). The antioxidant defense system is an important mechanism for plants to alleviate water stress, and how to effectively enhance the function of this system has always been a research focus. Sun et al. (2023) took A. roxburghii as the research object, to explore the role of exogenous spermidine (Spd) in alleviating water stress. The experiment used PEG6000 to simulate different degrees of drought. The results showed that under moderate water stress, the growth of A. roxburghii plants was restricted, manifested as a decrease in plant height, fresh weight, leaf area and stem diameter. At the same time, the activities of antioxidant enzymes (SOD, POD, CAT) and key enzymes of polyamine metabolism (ADC, SAMDC, PAO) decreased. However, the MDA, H2O2 and electrical conductivity of membrane lipid peroxidation products increased significantly. However, after foliar spraying of an appropriate amount of Spd (0.5mM), the plants exhibited a significant stress relief effect. The contents of soluble protein and proline increased, MDA, H2O2 and electrical conductivity decreased, and the activity of antioxidant enzymes was enhanced, thereby effectively reducing oxidative damage and maintaining the integrity of cell membranes (Figure 3). Meanwhile, Spd treatment promoted the accumulation of endogenous polyamines (e.g., Put, Spd and Spm), improved metabolic balance and enhanced the overall drought resistance of plants. It is worth noting that, the effect of low-concentration Spd is superior to that of high-concentration SPD, showing a dose-dependent approach. Figure 3 Cluster heat map analysis summarizing A. roxburghii responses to exogenous Spd treatment (Spd1: 0.5 mM, Spd2: 5 mM) under water stress (PEG1, PEG2, PEG3) on different treatment days (0d, 5d, 10d, 15d) (Adopted from Sun et al., 2023) 7 Discussion 7.1 Overall effects of growth regulators on root development Studies have shown that the combined use of growth regulators (IBA and NAA or IBA and 6-BA), is generally more effective than single hormone treatment in promoting the number of roots, root length and fresh weight of A. roxburghii tissue culture. When 1.0 mg/L IBA and 1.0 mg/L NAA were added to the MS medium, the rooting rate could reach 92%, and the stem and leaf growth was better than that of the single hormone treatment group (Zhang et al., 2025a). Furthermore, the application of strigolactone under phosphorus deficiency conditions, can promote root elongation and reduce oxidative damage, further supporting the advantages of the application of compound or synergistic regulators (Zhong et al., 2025).
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