Salt accumulation in vivipavous mangrove plants of Rhizophoraceae

红树科胎生红树植物盐分积累

• 批准号: 12640653
• 负责人: TAKASU Tokushiro
• 金额: $ 0.77万
• 依托单位: University of the Ryukyus
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640653/
• 关键词: Salt resistance; Viviparous germination; embryo; Rhizophoraceae; Mangrove plants

The embryo of Rhizophora mucronata Lam. Shows viviparous germination which is characteristic for the mangrove plants, and the endosperm continues to grow and protrudes from the micropyle. We first used the term, aril for endosperm, but this ontogentetical study clarified that the protruded structure should be termed as endosperm. This protruded endosperm continues to develop in the carpel wall and finally protrudes from the carpel wall. The top portion of endosperm takes position between the hypocotyl of the embryo and carpel wall. In the early stage of seed development, the embryo grows by the nutrients supplied by the degeneration of endosperm cells. In the later stage, however, it grows by the nutrients resulted from the degeneration of seed coat cells. In the early stage of seed development, the endosperm cells grow absorbing nutrients produced by the degeneration of seed coat and endocarp cells. The generation of endosperm cells, seed coat cells and carpel wall cells begins by the disappearance of tonoplast in the vacuole. After this disappearance organelles in the cytoplasm become distorted and finally disperse as small particles in the cytoplasm. The plasma membrane in cells alive next to degenerating cells appears as quite active and highly undulated. The absorption of the nutrients by the degenerated materials seems to be by endocytosis. The salt contents in the endosperm increases gradually, or it is low when embryo is small and entirely surrounded by endosperm while it is high when the hypocotyle protrudes from the carpel wall and takes position between the carpel wall and hypocotyl. The above mentioned results support the working hypothesis that the endosperm protruded from the carpel wall has a function to protect the embryo portion inside the fruit from the attack by fungi and bacteria which might find the way into the fruit. The accumulation of high concentration salt acts as natural antibiotic.

毛尖红树Rhizophora mucronata Lam.显示胎生萌发，这是红树林植物的特征，胚乳继续生长并从珠孔伸出。我们最初用假种皮来表示胚乳，但这项个体发育学研究澄清了突出的结构应该被称为胚乳。这种突出的胚乳在心皮壁中继续发育，最后从心皮壁突出。胚乳的顶部位于胚的下胚轴和心皮壁之间。在种子发育的早期阶段，胚的生长主要依靠胚乳细胞退化提供的营养物质。后期则靠种皮细胞退化后的营养物质生长。在种子发育的早期，胚乳细胞吸收种皮和内果皮细胞退化产生的营养物质生长。胚乳细胞、种皮细胞和心皮壁细胞的发生始于液泡膜的消失。在此消失后，细胞质中的细胞器变得扭曲，最终分散为细胞质中的小颗粒。与退化细胞相邻的活细胞的质膜表现为相当活跃和高度起伏。退化物质对养分的吸收似乎是通过内吞作用。胚乳含盐量逐渐增加，当胚小且完全被胚乳包围时，胚乳含盐量低，当下胚轴伸出心皮壁并位于心皮壁与下胚轴之间时，胚乳含盐量高。上述结果支持了这样一个假说：从心皮壁伸出的胚乳具有保护果实内胚部分免受真菌和细菌侵入果实的作用。高浓度盐的积累起着天然抗生素的作用。