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林业科学 ›› 2020, Vol. 56 ›› Issue (10): 145-153.doi: 10.11707/j.1001-7488.20201016

• 论文与研究报告 • 上一篇    下一篇

湿地松树木形成层恢复活动期、活动期和休眠期原始细胞超微结构变化

徐有明,周彩霞,林汉,陶吉云,张菊花   

  1. 华中农业大学园艺林学学院 武汉 430070
  • 收稿日期:2018-08-07 出版日期:2020-10-25 发布日期:2020-11-26
  • 基金资助:
    国家自然科学基金项目(NSFC31570551)

Ultrastructural Changes of the Cambial Cells of Pinus elliottii during the Periods of Recovery Activity, Activity and Dormancy

Youming Xu,Caixia Zhou,Han Lin,Jiyun Tao,Juhua Zhang   

  1. College of Horticulture&Forestry Sciences, Huazhong Agricultural University Wuhan 430070
  • Received:2018-08-07 Online:2020-10-25 Published:2020-11-26

摘要:

目的: 以树木形成层细胞分生分化活动为主线,探讨湿地松木材形成过程,为湿地松人工林培育、材性材质改良和森林资源利用提供科学依据。方法: 制作超薄切片,采用透射电镜观察湿地松年生长不同活动期形成层原始细胞超微结构变化及其木材形成过程。结果: 湿地松形成层纺锤形细胞的出现标志着细胞打破休眠期进入恢复活动期。2月底至3月底为形成层细胞恢复活动期,部分自溶现象发生于形成层细胞径向壁,尤其在细胞壁连接处,纺锤形细胞径向壁和弦向壁厚度差异不显著,呈椭圆形或近圆形,形成层纺锤形细胞出现少许质壁分离现象,淀粉颗粒出现明显电子透明区。4月初至10月底为形成层细胞活动期,整个形成层带细胞高度液泡化,细胞形状变得不规则,径向壁和弦向壁均变薄,弦向壁更薄且变得不明显,油滴和淀粉颗粒急剧减少。6月中旬为形成层细胞活动旺盛期,形成层带细胞层数明显增加,次生壁开始加厚,原生质体基本瓦解并消失。10月底至次年2月底形成层细胞处于休眠期,形成层带细胞层数明显减少,只含有1~2层扁平的厚壁纺锤形细胞,径向壁和弦向壁明显增厚,细胞内含物开始积累。整个活动期内形成层细胞径向壁明显比弦向壁厚,休眠期这种差异更明显,细胞壁特别是径向壁变薄是形成层恢复活动的主要特征。整个生长季均出现松针脱落现象,休眠期也有新的松针产生,松针产生和脱落与形成层细胞的休眠和激活无明显关联。次生木质部中成熟的射线细胞一直含有较多内含物,其原生质体没有出现衰退现象,说明次生木质部中的射线薄壁细胞多年内仍保持较高生理活性,以备在形成层细胞受伤后射线薄壁细胞转化为形成层细胞进行新的分裂分生活动。结论: 湿地松形成层细胞层数基本为1~2层,其年活动期内具有明显的休眠期和活动期变化。2月底至3月底为形成层细胞恢复活动期;4月初至10月底为形成层细胞活动期,是木材形成的主要阶段;6月中旬为形成层细胞活动旺盛期;10月底至次年2月底为形成层细胞休眠期。各时期内,形成层细胞层数、径向壁和弦向壁厚度、细胞内含物差异很大。

关键词: 湿地松, 形成层, 恢复期, 活动期, 休眠期, 形成层原始细胞, 超微结构, 木材形成

Abstract:

Objective: Wood formation is mainly controlled by the number of cambium cell division, which determines the biomass production and wood quality. The differentiation from cambium cell to mature xylem as the main line, this article discussed the wood formation processes of Pinus elliottii with aims to provide scientific guidance for the tree growth development, wood genetic improvement and wood resourse utilization of P. elliottii plantation. Method: In this paper, we mainly used transmission electron microscope (TEM) to investigate the activity regularity of cambium in detail during the wood formation of P. elliottii at the cellular ultrastructure level. Result: P. elliottii underwent annual cycles of cambial during periods of cambial activity and dormancy. The appearance of dividing fusiform cells in cambium indicated that the cells broke dormancy into recovery activity. From the end of February to the end of March, the period of transition from dormancy to activity, namely the recovery period, some autolysis occurred in the radial walls of the cambial cells, especially at the cell wall junctions. At this time, there was no significant difference between the radial wall and the tangential wall of the cambium fusiform cells that showed oval or nearly round. During the activity period from the beginning of April to the end of October, the whole cambial fusiform cells were highly vacuolated and the cell shape became irregular, both the radial wall and the tangential wall became thinner, the tangential wall was thinner and inconspicuous, the lipid droplets and starch granules decreased dramatically. The cambial activity reached the strong active phase in mid-June, the number of cells in the cambium was significantly increased and the secondary wall began to thicken. At this time, the protoplasts basically disintegrated and disappeared. The cells were dormant at the end of October to the end of the next year, the number of layers of cambium was significantly reduced, only contained 1-2 layers of thick-walled fusiform cells, the radial wall and tangential wall of the fusiform cells were significantly thickened and the inclusions of the cells began to accumulate. During the entire active period, the radial wall was significantly thicker than the tangential wall, while the differences were more obvious during the dormant period. A notable feature of the cells at the onset of cambial activity was the thinning of the cell wall, especially the radial wall. There were pine needles falling during the whole growing season and new pine needles were produced during the dormancy period, indicating that there was no obvious correlation between pine needle production and shedding and dormancy and activation of the cambial cells. The mature ray cells in the secondary xylem always contained more inclusions, and the protoplasts did not show any recession, indicating that the ray parenchyma cells maintained a high activity even after lignification for several years. Conclusion: There is a clear annual cycle of cambial for slash pine, with periods of cambial activity and dormancy. From the end of February to the end of March, it is a recovery period, and the activity period is from the beginning of April to the end of October, which is the period of slash pine wood formation. The cambial activity reaches the strong active phase in mid-June, the number of cells in the cambium is significantly increased and the secondary wall begins to thicken. The cells are dormant at the end of October to the end of the next year, the number of layers of cambium is significantly reduced, only contains 1-2 layers of thick-walled fusiform cells. In different periods of cambial activity, there are significant differences in number of layers of cambium, the radial wall and tangential wall of the fusiform cells and its cell inclusions.

Key words: Pinus elliottii, cambium, the recovery period, active period, dormancy period, cambial cell, ultrastructure, wood formation

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