Gricar Jozica, Zupancic Martin, Cufar Katarina, Koch Gerald, Schmitt Uwe, Oven Primoz
University of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Rozna dolina, Cesta VIII/34, SI-1000 Ljubljana, Slovenia.
Ann Bot. 2006 Jun;97(6):943-51. doi: 10.1093/aob/mcl050. Epub 2006 Apr 13.
BACKGROUND AND AIMS The effect of heating and cooling on cambial activity and cell differentiation in part of the stem of Norway spruce (Picea abies) was investigated.
A heating experiment (23-25 degrees C) was carried out in spring, before normal reactivation of the cambium, and cooling (9-11 degrees C) at the height of cambial activity in summer. The cambium, xylem and phloem were investigated by means of light- and transmission electron microscopy and UV-microspectrophotometry in tissues sampled from living trees.
Localized heating for 10 d initiated cambial divisions on the phloem side and after 20 d also on the xylem side. In a control tree, regular cambial activity started after 30 d. In the heat-treated sample, up to 15 earlywood cells undergoing differentiation were found to be present. The response of the cambium to stem cooling was less pronounced, and no anatomical differences were detected between the control and cool-treated samples after 10 or 20 d. After 30 d, latewood started to form in the sample exposed to cooling. In addition, almost no radially expanding tracheids were observed and the cambium consisted of only five layers of cells. Low temperatures reduced cambial activity, as indicated by the decreased proportion of latewood. On the phloem side, no alterations were observed among cool-treated and non-treated samples.
Heating and cooling can influence cambial activity and cell differentiation in Norway spruce. However, at the ultrastructural and topochemical levels, no changes were observed in the pattern of secondary cell-wall formation and lignification or in lignin structure, respectively.
背景与目的 研究了加热和冷却对挪威云杉（Picea abies）部分茎干形成层活性和细胞分化的影响。
在春季形成层正常重新激活之前进行加热实验（23 - 25摄氏度），并在夏季形成层活动高峰期进行冷却（9 - 11摄氏度）。通过光学显微镜、透射电子显微镜和紫外显微分光光度法对从活树上采集的组织中的形成层、木质部和韧皮部进行研究。
局部加热10天在韧皮部一侧引发形成层分裂，20天后在木质部一侧也引发分裂。在对照树中，30天后开始正常的形成层活动。在热处理样本中，发现有多达15个正在分化的早材细胞。形成层对茎干冷却的反应不太明显，在10天或20天后，对照样本和冷却处理样本之间未检测到解剖学差异。30天后，在冷却处理的样本中开始形成晚材。此外，几乎未观察到径向扩展的管胞，形成层仅由五层细胞组成。低温降低了形成层活性，晚材比例降低表明了这一点。在韧皮部一侧，冷却处理样本和未处理样本之间未观察到变化。
加热和冷却可影响挪威云杉的形成层活性和细胞分化。然而，在超微结构和拓扑化学水平上，分别未观察到次生细胞壁形成和木质化模式或木质素结构的变化。
