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Visualization of formation of lignified cell wall by microautoradiography

通过显微放射自显影观察木质化细胞壁的形成

基本信息

批准号：
08660203
负责人：
YASUDA Seiichi
金额：
$ 1.47万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08660203/
关键词：
cell wall cellulose lignin hemicellulose tree radio tracer microautoradiography

项目摘要

Selective radio-labeling of mannan in ginkgo and pine was achieved by the administration of D-mannose- [2-3H] in the presence of both glucan biosynthesis inhibitor and phenylalanine ammonia-lyase inhibitor, namely, 2-deoxy-D-glucose and L-a-aminooxy-b-phenylpropionic acid, respectively, to growing stems. To study the deposition and distribution of mannan during cell wall formation, the distribution of the radioactivity in differentiating xylem was visualized by microautoradiography. Radioactivity was incorporated into the cell walls for a long period from early stage to S3 (inner layr of secondary wall) formation stage. The incorporation was most significant at the stage following the start of S1 (outer layr of secondary wall) formation. This result indicates that mannan deposition was enhanced during secondary wall formation and mannan is present mainly in secondary wall.The role of monolignol glucosides was also investigated by the feeding of radiolabeled coniferin and syringin into magnolia tree. It was suggested that syringin was not the direct precursor of lignin because of low concentration in lignifing tissues and grawing seasons. Microautoradiographic studies revealed that administered syringin was incorporated into cortex in the bark even in the non-lignifying season. While, coniferin was incorporated into the differentiating xylem and phloem fiber during the lignifing season, which indicated that coniferin is involved in the lignin biosynthesis.

在2-脱氧-D-葡萄糖和L-a-氨基氧基-b-苯丙酸的存在下，分别用葡聚糖生物合成抑制剂和苯丙氨酸解氨酶抑制剂D-甘露糖[2-~3H]标记银杏和松树的甘露聚糖。为了研究细胞壁形成过程中甘露聚糖的沉积和分布，用显微放射自显影技术观察了分化木质部中的放射性分布。从早期到S3(次生壁内层)形成阶段，放射性进入细胞壁的时间较长。在S1(次生壁的外层)形成开始后的阶段，结合最为显著。这一结果表明，在次生壁形成过程中，甘露聚糖的沉积增加，并且甘露聚糖主要存在于次生壁中。通过向厚朴树中投喂放射性标记的松柏苷和丁香苷，研究了单醇糖苷的作用。这表明紫丁香苷不是木质素的直接前体，因为它在木质化组织和采摘季节中的浓度很低。显微放射自显影研究表明，即使在非木质化的季节，给药的紫丁香素也被合并到树皮的皮质中。而针叶木素在木质化季节进入分化的木质部和韧皮部纤维中，表明松柏木素参与了木质素的生物合成。