Objective Microstructures and polysaccharide contents in the wild Dendrobium officinalein in Danxia landform areas and artificially propagated seedlings were compared for product differentiation and cultivation of the valuable herbal medicinal material.
Methods At areas of Danxia landform, stems from wild and 2-3 year old cultivated D. officinalein plants were collected for microscopic morphological examination as well as histochemical and chemical analyses.
Results The reddish-purple stems of the wild D. officinalein plants bore dark greenish-purple leaves with no visible internodes. In contrast, the artificially propagated seedlings had light green leaves on dark green stems with internodes. In addition, the plant height, stem diameter, and internode distance of the cultured seedlings were greater than those of the plants found in the wild. There were also significant differences between them in the cuticle thickness, epidermal cell diameter, subcutaneous cell diameter and layer number, sheath fiber diameter and number, vascular bundle diameter and number, xylem and phloem thickness, calcium oxalate needle length, catheter diameter, wood parenchyma cell diameter, and sheath cell wall thickness of the plants. A large amount of polysaccharide granules existed in aggregation in the tissues of the cultivated seedlings which turned its deep reddish purple color by staining darker than those in the wild D. officinalein. The granules differed in size as well. However, the wild D. officinalein had a higher content of polysaccharides than the propagated seedlings.
Conclusion With respect to the microstructure and metabolites of the stems, there were significant differences between the D. officinalein in the wild and the cultivated seedlings. The morphology, microstructure, histochemical localization, and polysaccharide content of the medicinal material could be adequate indicators in identifying, evaluating, and differentiating the products of different origins.
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