Medicinal Plant Research 2024, Vol.14, No.1, 31-44 http://hortherbpublisher.com/index.php/mpr 35 3.2 Genetic basis of stress resistance The genetic basis of stress resistance in yam is multifaceted, involving numerous genes and pathways. The identification of endogenous gibberellins in dormant bulbils of yam highlights the role of these hormones in dormancy and stress resistance (Tanno et al., 1992). Gibberellins are known to regulate various aspects of plant growth and development, including responses to environmental stress. Furthermore, the transcriptome assembly and gene expression analysis of yam identified a significant number of simple sequence repeats (SSRs) and differentially expressed genes, which are likely involved in stress response mechanisms (Hou et al., 2020). These genetic elements provide a foundation for understanding how yam copes with environmental stress and maintains its medicinal properties. Calcium-dependent protein kinases play important roles in plant growth, development, and responses to stress. The cloned calcium-dependent protein kinase gene DoCDPK1 shows 97% similarity with the CDPK protein sequence of Dioscorea rotundata. DoCDPK1 contains the STKc_CAMK domain. Following cold stress at 4 °C, CDPK activity decreases while DoCDPK1 expression increases, with expression levels varying at different time points of treatment. DoCDPK1 is likely involved in regulating growth and development during the late stages of yam tuber enlargement and in response to cold stress (https://doi.org/10.16861/j.cnki.zggc.2024.0164). Yam polysaccharides possess anti-aging pharmacological activities. Transcriptomic data reveal that this anti-aging effect may be related to autophagy, mTOR, and insulin signaling pathways (https://mall.cnki.net/magazine/article/SJZA202404004.htm). In yam anthracnose, transcriptomic analysis shows that WRKY, MYB, and TIFY transcription factors positively or negatively regulate the expression of disease resistance genes. Transcriptionally regulated proteins include PR proteins, NBS-LRR disease resistance genes, and receptor kinases, with increased expression of antioxidant protective enzyme systems CAT and SOD under oxidative stress stimuli (Han et al., 2022). 3.3 Evolutionary comparison with related species Comparative genomic studies between yam and related species offer insights into the evolutionary processes that have shaped its adaptive traits. For example, the molecular phylogenetic analysis of D. opposita using 18S rDNA and chloroplast 16S rDNA sequences revealed significant genetic similarities and differences with other species in the Dioscoreaceae family (Hou et al., 2011). This phylogenetic information is crucial for understanding the evolutionary history and adaptive evolution of yam. Additionally, the study of NBS-LRR genes in Dioscorea rotundata, a related species, provides a comparative framework for investigating disease resistance genes in yam (Zhang et al., 2020). The evolutionary analysis of these genes suggests that yam may share similar mechanisms of pathogen resistance, further highlighting the adaptive evolution of this species. In summary, the adaptive evolution of yam is characterized by its environmental adaptations, genetic basis of stress resistance, and evolutionary comparisons with related species. These factors collectively contribute to the plant's resilience and medicinal properties, making it a valuable subject for further research in plant genomics and evolutionary biology. 4 Medicinal Properties of Yam 4.1 Overview of medicinal uses in traditional medicine Yam has been extensively utilized in traditional Chinese medicine (TCM) for its beneficial effects on the spleen and stomach. It is often employed to treat conditions such as diarrhea, fatigue, and loss of appetite. The rhizome of yam is particularly valued for its ability to regulate digestive functions and enhance overall vitality (Zhang et al., 2019; Yu et al., 2020). Additionally, it has been used in various oriental countries, including Japan and Korea, as a traditional herbal remedy for its neuroprotective properties (Yu et al., 2020). 4.2 Bioactive compounds and their biosynthesis The medicinal properties of yam are attributed to its rich content of bioactive compounds, including polysaccharides, steroidal saponins, and phenanthrenes. A novel polysaccharide, DOP0.1-S-1, isolated from the rhizome, has shown significant bioactivity by promoting the growth of beneficial gut bacteria and producing
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