果胶酶的细胞化学定位：马尾松树脂道发生的细胞化学证据

运用薄切片和电镜细胞化学方法观察了马尾松(Pinus massoniana Lamb.)茎皮层树脂道的发育及发育过程中果胶酶的变化。树脂道的发育过程一般可分为4个阶段,即原始细胞阶段、胞间隙形成阶段、腔道扩大阶段和树脂道成熟阶段。在原始细胞阶段,果胶酶的反应产物首先出现在原始细胞膨胀的细胞壁角隅处,然后沿细胞壁中层分布。胞间隙形成后,果胶酶的反应产物分布在细胞壁和胞间隙的交界面。随着胞间隙的扩大,反应产物的密度逐渐降低。当树脂道成熟后,上皮细胞壁上则没有果胶酶的反应产物出现。细胞化学证据表明: 在树脂道的发育过程中,果胶酶降解树脂道原始细胞细胞壁中层,支持树脂道以裂生方式形成。果胶酶的细胞化学定位技术还可用于其他植物中与果胶水解有关的发育过程。

Cytochemical Localization of Pectinase: the Cytochemical Evidence for Resin Ducts Formed by Schizogeny in Pinus massoniana

Initiation and development of resin ducts were studied in cortex of stem of Pinus massonianaLamb. by thin section. It is shown that the development of resin ducts can be divided into four stages: theinitial stage, the intercellular space forming stage, the lumen expanding stage and the mature stage. Tofurther investigate the original mode of resin ducts, cytochemical localization of pectinase with atransmission electron microscope (TEM) was conducted. Results showed that the pectinase was activeduring resin duct development. At the initial stage, reaction products of pectinase first appeared in thecorner of swollen cell wall among the future epithelial cells and later along the walls. At the intercellularspace forming stage, reaction products occurred in the cell wall/intercellular space interface and itsdensity decreased while the intercellular space enlarged. At the mature stage, no reaction products werefound in the walls of the epithelial cells. These results indicate that pectinase catalyzes the degradation ofthe middle lamella of the epithelial cells during the resin ducts development. The cytochemical evidencesupports that the resin ducts are formed by schizogeny. This report represents the first direct evidencefor the involvement of pectinase in resin ducts formation .