Study on Morphological Structure and Ergastic Substance of Different Nutrient Organs in Paeonia ludlowii
In order to explore the growth and development of Paeonia ludlowii,as well as the synthesis and accumulation of ergastic substance,optical microscopy was used to observe the morphological structure of different vegetative organs,including root,stem and petiole,to analyze the species and contents of the ergastic substance.The results showed that the cortex and periderm of the nutritional organs of Paeonia ludlowii were well-developed,the phloem was thick and the cell volume was large,and there was a large amount of ergastic substance.By staining with potassium-iodine,the active substance in the rhizome was found to be starch granules.Analyzing the content of starch and soluble sugar,it was found that the starch in root was much higher than that in stem.From the cross-sectional view of roots and stems,the starch was mainly distributed in the parenchyma cell of phloem and low in xylem.The content of soluble sugar in root was much higher than that in stem,and that in the bark was slightly higher than that in the xylem of stem.These results demonstrated that the soluble sugars,produced by photosynthesis,were vertically transported to root for synthesis and storage of starch,which reflected the evolutionary results for response to wicked conditions such as high altitude,prolonged cold,and drought.Our results will expand the understanding of morphological structure and the patterns of ergastic substance synthesis and accumulation in plateau plants,and provide a theoretical basis for future research of adaptation mechanisms to extreme environments.
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