人工林毛白杨次生木质部细胞分化过程中木质素沉积的动态变化

本文以高锰酸钾(KMnO4)染色及醋酸双氧铀和柠檬酸铅双染色两种方法,利用透射电镜技术(TEM)研究人工林毛白杨(Populus tomerttosa Carr．)木质部细胞分化过程中木质素在细胞壁上的沉积方式,并讨论了细胞壁结构与木质素沉积之间的关系。观察结果表明,木质素最早出现在位于初生壁的细胞角隅处,以分散的条形颗粒状沉积。随着S1和S2层纤维素微纤丝(CMfs)的沉积,木质素开始沿初生壁角隅处,向胞间层其它区域和次生壁各层同时扩展,整个木质化过程并不是由胞间层依次向次生壁各层推进。S3层的CMfs沉积后,木质素在整个次生壁开始迅速沉积。次生壁上的木质素主要以不均匀团块状方式沉积,且各层交界处的木质素沉积较少。胞问层沉积的木质素多且较次生壁沉积的更为致密。木质素的沉积方式可能与细胞壁各层纤维素微纤丝骨架的不同结构密切相关。

Dynamic changes of lignin deposition in secondary xylem cell wall during secondary xylem differentiation in Populus tomentosa carr

In this paper, the dynamic changes of lignin deposition and the connection between lignification progress and cellulose microfibrils (CMfs) structure in cell wall were analyzed on the basis of cytochemistry localization of lignin and CMfs with KMnO_4 staining, and lead citrate and uranyl acetate staining. Lignin deposition with a style of numerous discrete granules occurred firstly at the corner of the middle lamella within various primary cell walls. Accompanying with the deposition of cellulose microfibrils (CMfs) in secondary wall S_1 and S_2, lignification extended from corner to rest regions of the middle lamella and the secondary wall at the same time. However, the whole lignification process did not expand from the middle lamella to each layer of the secondary wall in turn. After CMfs deposition in S_3, lignin deposition occurred rapidly with irregular patches in whole secondary walls. Totally, the density of lignin deposition in the middle layer was higher than that in the secondary wall, and also there was less lignin distribution on the layer boundaries than within each layer of the secondary wall. These present results indicate that CMfs skeletons with different structure distributed within different wall layers probably played an important role during lignin deposition.