莲种子萌发和幼苗生长时期营养物质的代谢变化

莲子叶细胞中储存了丰富的营养物质, 主要为蛋白质、淀粉和淀粉质体DNA。这些贮藏物质为种子萌发和幼苗的生长提供必需的能量和养料。通过组织化学和显微镜观察, 研究莲从种子萌发到植株生长至具有4个节时, 子叶中贮藏物质消耗的全过程。在此过程中, 子叶中的贮藏物质不断降解,营养物质发生转运。蛋白体首先发生降解, 其大量降解主要发生在幼苗三叶期。淀粉质体降解时会聚集成团, 之后体积逐渐减小, 最后完全降解。种子萌发后65天是子叶贮藏物质消耗末期, 淀粉质体DNA的含量比萌发后20天的三叶期明显减少。细胞壁的形态结构发生多种形式的变化, 细胞壁发生的这些变化与子叶细胞间物质的运输有关。含多糖的球形颗粒通过维管束在子叶中运输。

Degradation Metabolism of Storage Reserves During Seed Germination and Seedling Growth of Sacred Lotus (Nelumbo nucifeva)

The cotyledons of Sacred Lotus (Nelumbo nucifeva) accumulate abundant storage reserves, including storage proteins in protein bodies, starch and DNA in amyloplasts, during seed development. Hydrolysis of these reserves provides sources for seed germination and seedling growth. Histochemical analysis revealed the entire process of reserve degradation in Sacred Lotus cotyledons, which occurs from seed germination to the stage of 4-noded vegetal body over about 45 days. Throughout this period, storage reserves are continuously involved in dynamic hydrolysis and transport activities. Protein bodies degrade before starch and aDNA hydrolysis, which mainly occurs at the trefoil stage. Amyloplasts may fuse into a large starch mass and hydrolyze gradually. In comparison with the trefoil stage, amyloplasts contain few DNA after 65 days of germination. In addition, diverse structural changes, related to transporta-tion of substances among cotyledon cells, occur in cell walls. Quantities of polysaccharide vesicles are transported in bulk through vascular bundles.