2006 Fiscal Year Final Research Report Summary
Biosynthesis of monolignols in the cell and their transportation toward cell wall
| Project/Area Number |
16380119
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林産科学・木質工学
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| Research Institution | Kyoto University |
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Principal Investigator |
TAKABE Keiji Kyoto University, Graduate School of Agriculture, Associate Professor, 農学研究科, 助教授 (70183449)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHINAGA Arata Kyoto University, Graduate School of Agriculture, Assistant Professor, 農学研究科, 助手 (60273489)
AWANO Tatsuya Kyoto University, Graduate School of Agriculture, Assistant Professor, 農学研究科, 助手 (40324660)
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| Project Period (FY) |
2004 – 2006
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| Keywords | lignin / monolignol / F5H / SAD / laccase / ATP / membrane protein |
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| Research Abstract |
Lignification is thought to proceed in three steps. The first step is synthesis of monolignols in the cell, and following one is their transport toward cell wall. The final step is polymerization of monolignols within the cell wall. Many enzymes are known to be involved in synthesis of monolignols. We observed the immunolocalization of ferulate 5-hydroxylase (F5H) and sinapylalcohol dehydrogenase (SAD). Immunolabeling of F5H was observed in differentiating xylem of poplar. The labeling was observed on the membrane of rough endoplasmic reticulum in the cells during secondary wall formation. Immunolabeling of SAD was also observed in differentiating xylem of poplar. However, the labeling was localized on the cyto-sol during secondary wall formation. These results suggest that the conversion of furulic acid to 5-hydroxy ferulic acid and/or coniferyl aldehyde to 5-hydroxy coniferyl aldehyde occur on the membrane of rough endoplasmic reticulum. On the contrary, conversion of sinapyl aldehyd
… More
e to sinapyl alcohol may occur in the cyto-sol.
Monolignols synthesized in the cell are transported toward developing cell wall through the plasma membrane. We prepared microsomal fraction from differentiating xylem of poplar by ultra-centrifugation, and incubated with several kinds of monolignols and their related substances with or without ATP. Coniferin was actively incorporated into the microsomal fraction with the presence of ATP. On the contrary, coniferyl alcohol was not incorporated.
Peroxidases and laccases are thought to be involved in polymerization of monolignols. We already observed the localization of anionic peroxidase which is localized on the plasma membrane of differentiating xylem cells in poplar. Heavy immunolabeling of laccase was observed on the inner surface of ray parenchyma cells in differentiating xylem of poplar. A few immunolabeling of laccase was detected on the cell wall of differentiating xylem cells. This result suggested that laccase is not involved in polymerization of monolignol within the cell wall in poplar. Less
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