Laboratory of Tree Cell Biology, Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
Ann Bot. 2012 Sep;110(4):897-904. doi: 10.1093/aob/mcs144. Epub 2012 Jul 9.
Although tension wood formation and the structure of gelatinous fibres (G-fibres) have been widely investigated, studies of the influence of the reaction phenomenon on phloem fibres have been few and incomplete in comparison with those of xylem wood fibres. This study was undertaken to clarify the influence of stem inclination on phloem fibres using several Japanese hardwood species that produce different G-fibre types in tension wood.
Eight hardwood species were inclined at 30-45° at the beginning of April. Specimens were collected in July and December. The cell-wall structure and lignin distribution of phloem fibres on both the tension and opposite sides were compared by light microscopy, ultraviolet microscopy, confocal laser scanning microscopy after staining with acriflavine, and transmission electron microscopy after staining with potassium permanganate.
Three types of changes were found in tension-side phloem fibres: (1) increases in the proportion of the syringyl unit in lignin in the S(1) and S(2) layers and compound middle lamella (Cercidiphyllum japonicum), (2) formation of unlignified gelatinous layers (Melia azedarach and Acer rufinerve) and (3) increases in the number of layers (n) in the multi-layered structure of S(1) + S(2) + n (G + L) (Mallotus japonicus). Other species showed no obvious change in cell-wall structure or lignin distribution.
Phloem fibres of the tree species examined in our study showed three types of changes in lignin distribution and cell-wall structure. The reaction phenomenon may vary with tree species and may not be closely related to G-fibre type in tension wood.
尽管已经广泛研究了张力木的形成和凝胶纤维（G 纤维）的结构，但与木质部木纤维相比，对韧皮部纤维受反应现象影响的研究较少且不完整。本研究旨在使用几种在张力木中产生不同 G 纤维类型的日本阔叶树种，阐明茎倾斜对韧皮部纤维的影响。
8 个硬木树种在 4 月初以 30-45°的角度倾斜。7 月和 12 月采集标本。通过光镜、紫外线显微镜、吖啶橙染色后的共聚焦激光扫描显微镜和高锰酸钾染色后的透射电子显微镜比较张力侧和对侧韧皮部纤维的细胞壁结构和木质素分布。
张力侧韧皮部纤维发现了 3 种变化：（1）S（1）和 S（2）层以及复合中层（Cercidiphyllum japonicum）木质素中愈创木基单元比例增加，（2）形成无木质素的凝胶层（Melia azedarach 和 Acer rufinerve），以及（3）S（1）+S（2）+n（G+L）多层结构中 n 层数量增加（Mallotus japonicus）。其他物种的细胞壁结构或木质素分布没有明显变化。
我们研究的树种的韧皮部纤维显示出木质素分布和细胞壁结构的 3 种变化。反应现象可能因树种而异，可能与张力木中的 G 纤维类型没有密切关系。
