Relationship between the earlywood-to-latewood transition and changes in levels of stored starch around the cambium in locally heated stems of the evergreen conifer Chamaecyparis pisifera
Relationship between the earlywood-to-latewood transition and changes in levels of stored starch around the cambium in locally heated stems of the evergreen conifer Chamaecyparis pisifera
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DOI：
10.1007/s00468-016-1395-4
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发表时间：
2016-10-01
影响因子：
2.3
通讯作者：
Funada, Ryo
中科院分区：
文献类型：
--
作者：
Rahman, Md Hasnat;Begum, Shahanara;Funada, Ryo
在常绿针叶树樟树的冬季形成层休眠过程中，树干局部受热区形成了直径窄、壁厚的晚枝管胞，形成层周围储存的淀粉消失。木材的形成受形成层细胞分裂的控制，形成层细胞分裂决定了木材的数量和质量。本文研究了常绿针叶树（Chamaecyparis pisifera）局部加热茎中形成层活性和新管胞形成的控制因素。在2013年和2014年，分别有两棵树在与乳房高度相同的树干一侧缠上了电热胶带。在冬季对茎进行局部加热，并从茎的加热区和非加热区收集小块。在显微镜下观察了形成层的活性和周围储存淀粉的水平。加热区形成层的活化和木质部的分化早于非加热区。加热14-18天后形成新的细胞板。在形成几层直径大、壁薄的管胞后，细胞分裂和分化过程中的细胞扩大受到抑制。在形成层附近形成直径较窄、壁较厚的管胞，并最终形成4 ~ 6层管胞。在形成层活化后，加热区分化过程中，位于形成层附近的韧皮部和木质部细胞中的淀粉储存量开始减少，淀粉完全消失。我们的研究结果表明，温度的升高会诱导储存的淀粉转化为可溶性糖，从而促进形成层细胞的连续分裂和早期木材的形成。相反，贮藏淀粉的缺乏可能是抑制形成层活性和诱导后木管胞形成的原因。
We observed the formation of latewood tracheids with narrow diameters and thick walls and the disappearance of stored starch around the cambium on the locally heated region of stems in evergreen conifer Chamaecyparis pisifera during winter cambial dormancy.Wood formation is controlled by cambial cell division, which determines the quantity and quality of wood. We investigated the factors that control cambial activity and the formation of new tracheids in locally heated stems of the evergreen conifer Chamaecyparis pisifera. Electric heating tape was wrapped around one side of the stem, at breast height, of two trees in 2013 and two in 2014. Pairs of stems were locally heated in winter, and small blocks were collected from heated and non-heated regions of stems. Cambial activity and levels of stored starch around the cambium were investigated by microscopy. Cambial reactivation and xylem differentiation occurred earlier in heated than in non-heated regions. New cell plates were formed after 14-18 days of heating. After a few layers of tracheids with large diameters and thin walls had formed, cell division and cell enlargement during differentiation were inhibited. Tracheids with narrow diameters and thick walls, defining those as latewood, were formed near the cambium, and finally, four to six layers of tracheids were induced. After cambial reactivation, amounts of stored starch started to decrease and starch disappeared completely from phloem and xylem cells that were located near the cambium during the differentiation of heated regions. Our results suggest that an increase in temperature induces the conversion of stored starch to soluble sugars for continuous cambial cell division and earlywood formation. By contrast, a shortage of stored starch might be responsible for inhibition of cambial activity and induction of the formation of latewood tracheids.