Medicinal Plant Research 2025, Vol.15, No.4, 151-160 http://hortherbpublisher.com/index.php/mpr 154 3.2 Osmotic regulation and water balance When transplanting and under abiotic stress, like high temperature, drought or salt stress, the roots of A. roxburghii accumulate osmotic protective substances, such as soluble sugar and proline (Feng et al., 2023; Sun et al., 2023; Zhang et al., 2024). These compounds, help maintain cellular osmotic balance, stabilize proteins and membrane structures, and protect cells from dehydration and oxidative damage. Proline is particularly important. As a compatible solute, it can eliminate reactive oxygen species (ROS), and support the normal function of enzymes under stress conditions (Feng et al., 2023; Zhang et al., 2024). Osmotic regulation through the accumulation of soluble sugar, and proline enables root cells to retain water, maintain turgor pressure, and maintain metabolic activity under environmental stress (Feng et al., 2023; Sun et al., 2023). This process is conducive to root elongation, cell division and the recovery of root function. Enhanced osmotic regulation directly contributes to improving the survival rate of transplanting and the growth of subsequent plants, as it can alleviate the impact of water deficiency and accelerate the acclimation process (Zhang et al., 2024). 3.3 Reactive oxygen species (ROS) balance and antioxidant systems Transplanting and environmental stress, often lead to the excessive production of reactive oxygen species in roots, thereby causing oxidative damage to cellular components. A. roxburghii responds by up-regulating antioxidant enzymes, like superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) (Sun et al., 2023; Zhang et al., 2024; Zhong et al., 2025). These enzymes work in synergy to eliminate ROS, reduce lipid peroxidation and protect root cells from oxidative damage. For instance, the application of strigolactone under phosphorus stress conditions, can promote root elongation and reduce ROS accumulation by enhancing antioxidant enzyme activity (Zhong et al., 2025). Non-enzymatic antioxidants, such as polyamines and secondary metabolites (such as flavonoids), also play important roles in ROS detoxification, and cell protection (Sun et al., 2023; Ding et al., 2024). In A. roxburghii, overexpression of polyamine oxidase (PAOs), can enhance water stress resistance by regulating polyamine levels and strengthening antioxidant defense (Ding et al., 2024). Exogenous application of spermidine, has been proven to increase the content of endogenous polyamines, and the activity of antioxidant enzymes, further promoting root adaptation and recovery under water deficiency conditions (Sun et al., 2023). 4 Metabolic and Functional Changes in Anoectochilus roxburghii Roots 4.1 Energy metabolism regulation After transplanting, the metabolic demands of the root system of A. roxburghii increase significantly, to support adaptation and regeneration. Transcriptomic analysis indicated that, genes related to energy metabolism (glycolysis, tricarboxylic acid cycle (TCA), and mitochondrial electron transport chain related genes, etc.), were all upregulated, suggesting enhanced mitochondrial respiration during root recovery and active growth stages (Zhang et al., 2020a; Yu et al., 2025). The upregulation of energy metabolism pathways, leads to an increase in ATP production, which is important for root cell maintenance, ion transport and activation of stress response mechanisms (Zhang et al., 2020a; Chen et al., 2021). An adequate supply of ATP helps support the active transport process, cell membrane repair, and the synthesis of secondary metabolites. These processes collectively determine the successful adaptation, and survival of the root system after transplantation. 4.2 Secondary metabolite accumulation Transplanting and environmental factors, like the interaction between light quality and microorganisms, affect the accumulation of secondary metabolites in the root system of A. roxburghii. Studies have shown that, arbuscular mycorrhizal fungi (Ceratobasidium sp.AR2) and endophytic fungi, can increase the contents of flavonol glycosides, flavonols, flavonoids and total phenols, by up-regulating key biosynthetic genes (Ye et al., 2020; Zhang et al., 2020a; b; Li et al., 2024).
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