Seasonal dynamic changes of cell polysaccharide granules in cambium active phase of taxodium ascendens
Seasonal dynamic changes of cell polysaccharide granules in cambium active phase of taxodium ascendens
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DOI：
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发表时间：
2020
影响因子：
3.1
通讯作者：
Kunxi Wang
中科院分区：
文献类型：
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作者：
Jieyun Tao;Youming Xu;Cong Liu;Han Lin;Kunxi Wang
Pond cypress (Taxodium ascendens Brongn) is an important timber specie introduced and cultivated in the water grid region of Yangtze River in China. To study the changes of polysaccharide storage in the active phase of cambium is helpful to understand the mechanism of its wood formation and improvement, and to improve its wood economic value. Five Pond cypress trees were selected as samples. Samples were taken every 7 days from March to October, and every other month from November to March of the following year. The branches with good healthy growth of 1–3 years were selected and their middle parts was cut into 0.5~1.0 cm segments, and paraffin sections were made with a thickness of 10 μm, stained with PAS reaction, and photographed by OLYMPAS universal microscope. The contents in parenchyma of Pond cypress could be dyed purple red granules by PAS reaction, mainly polysaccharide granules (not starch granules). The vascular cambium of Pond cypress was active at the beginning of April. At this time, a large number of purple polysaccharide granules can be seen in various parenchyma, but they were not observed in vascular cambium. After that, the storage of polysaccharides in parenchyma tissue gradually decreased and disappeared at the end of July, which reflected the facts that a large number of daughter cells produced by cambium meristem division need to consume a lot of nutrients. At the beginning of August, a small amount of polysaccharides appeared in parenchyma tissues, at this time, the activity of cambium cells decreased, and the nutrients used for activity decreased. From August to the last ten days of September, the storage of polysaccharides in various parenchyma kept increasing, and the granules were larger; then, the storage of polysaccharides decreased, and the particles became smaller obviously. From September to the end of November, almost no polysaccharide was observed, which indicated that the newly produced daughter cell wall thickening and maturation consumed a lot of nutrients. From late January to early April of the following year, various parenchyma were filled with polysaccharides, which were needed for cambium activities in the coming year. The cambium division activities of Pond cypress form phloem at first and then xylem. The changes of storage materials in various parenchyma cells of wood are closely related to the division of cambium cells and the growth and maturation of daughter cells. The appearance of new mature phloem is beneficial to hydrolyze part of the stored polysaccharide granules to meet the needs of the cambium divisionactivities and tree growth.
