ROLE OF PEROXIDASE IN THE DEVELOPMENT OF WATER-IMPERMEABLE SEED COATS IN SIDA-SPINOSA L
ROLE OF PEROXIDASE IN THE DEVELOPMENT OF WATER-IMPERMEABLE SEED COATS IN SIDA-SPINOSA L
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DOI：
10.1007/bf00405186
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发表时间：
1983-01-01
期刊：
影响因子：
4.3
通讯作者：
DUKE, SO
中科院分区：
文献类型：
--
作者：
EGLEY, GH;PAUL, RN;DUKE, SO
在母株上的种子发育过程中，S. spinosa（带刺的sida， malvacae）的种皮变得不透水。在最后成熟阶段，种子脱水后，必须刺穿种皮，以诱导水的吸胀和发芽。在一种野生豌豆（Pisum elatius）种子的抗渗性发育过程中，多酚氧化酶（PO; EC 1.10.3.1）作为儿茶酚氧化酶参与了不溶性聚合物的形成。过氧化物酶（EC 1.11.1.7），而不是氧化酶（PO），在多刺豆不透水种皮的发育中起重要作用。皮和胚胎是从不同发育阶段的种子中分离出来的。果皮提取物的过氧化物酶活性与可溶性酚类物质转化为不溶性木质素聚合物的发育阶段密切相关。虽然种子提取物氧化二羟基苯丙氨酸，但该活性被过氧化氢酶消除，这表明过氧化氢酶催化了皮中酚类物质的氧化，而不是PO。过氧化物酶在栅栏层的组织化学定位最强；活性显现的程度和时间与种皮提取物的分光光度测定成正比。免疫细胞化学也证实了种皮中存在过氧化物酶，而不存在PO。显然，过氧化物酶参与了多刺sida种皮发育过程中可溶性酚类物质聚合成不溶性木质素聚合物的过程，导致种子脱水前形成不透水屏障。随着脱水的进行，合点区最终变得不透水，导致多刺sida的硬成熟种子。
The seed coats of S. spinosa (prickly sida, Malvaceae) become impermeable to water during seed development on the mother plant. After the seeds have dehydrated during the final maturation stages, piercing of seed coats is necessary to induce imbibition of water and germination. Onset of impermeability occurs during seed coat browning, well in advance of seed dehydration (Marbach and Mayer 1975) implicated polyphenol oxidase (PO; EC 1.10.3.1) as catechol oxidase in the formation of insoluble polymers during development of coat impermeability in a wild strain of pea (Pisum elatius) seeds. Peroxidase (EC 1.11.1.7), not PO, is instrumental in the development of water-impermeable seed coats in prickly sida. Coats and embryos were isolated from seeds harvested at several stages of development. Highest peroxidase activity of coat extracts correlated well with the developmental stages of maximum conversion of soluble phenolics to insoluble lignin polymers. Although seed extracts oxidized dihydroxyphenylalanine, this activity was eliminated by catalase, indicating that the oxidation of phenolics in the coat is catalyzed by peroxidase rather than PO. Histochemical localization of peroxidase was strongest in the palisade layer; the level and time of appearance of activity was proportional to the spectrophotometric assays of seed-coat extracts. The presence of peroxidase and the absence of PO in the seed coat were also confirmed with immunocytochemistry. Evidently, peroxidase is invovled in the polymerization of soluble phenolics to insoluble lignin polymers during development of prickly sida seed coats, causing the formation of a water-impermeable barrier prior to seed dehydration. As dehydration proceeds, the chalazal area finally becomes impermeable resulting in the hard mature seeds of prickly sida.