Schmitz Nele, Koch Gerald, Schmitt Uwe, Beeckman Hans, Koedam Nico
Royal Museum for Central Africa, Laboratory for Wood Biology and Xylarium, Leuvensesteenweg 13, 3080 Tervuren, Belgium.
Microsc Microanal. 2008 Oct;14(5):387-97. doi: 10.1017/S143192760808077X.
Intervessel pits play a key role in trees' water transport, lying at the base of drought-induced embolism, and in the regulation of hydraulic conductivity via hydrogels bordering pit canals. Recently, their microstructure has been the focus of numerous studies, but the considerable variation, even within species and the histochemistry of pit membranes, remains largely unexplained. In the present study, intervessel pits of the outermost wood were examined for Avicennia marina, of dry and rainy season wood separately for Rhizophora mucronata. The thickness of the pit membranes was measured on transmission electron micrographs while their topochemical nature was also analyzed via cellular UV microspectrophotometry. Pit membranes of R. mucronata were slightly thicker in dry season wood than in rainy season wood, but their spectra showed for both seasons a lignin and a yet unidentified higher wavelength absorbing component. It was suggested to be a derivative of the deposits, regularly filling pit canals. The vestures of A. marina chemically resembled pit membranes rather than cell walls.
导管间纹孔在树木水分运输中起关键作用，处于干旱诱导栓塞的基础位置，并通过纹孔道周围的水凝胶调节导水率。最近，它们的微观结构一直是众多研究的焦点，但即使在物种内部，纹孔膜的显著差异及其组织化学性质在很大程度上仍未得到解释。在本研究中，分别对白骨壤最外层木材的导管间纹孔进行了检查，对红树的旱季和雨季木材的导管间纹孔也分别进行了检查。在透射电子显微镜照片上测量纹孔膜的厚度，同时通过细胞紫外显微分光光度法分析其拓扑化学性质。红树旱季木材的纹孔膜比雨季木材的略厚，但其光谱显示两个季节都有木质素和一个尚未鉴定的高波长吸收成分。有人认为它是定期填充纹孔道的沉积物的衍生物。白骨壤的覆盖物在化学上更类似于纹孔膜而不是细胞壁。
