| Budget Amount *help |
¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Research Abstract |
The purpose of this project is to clarify the heterogeneity in structure and distribution of protolignin by application of the technique of selective labeling of specific structural moiety with ^3H or ^<14>C and visualization of formation process of labeled macromolecular lignin in the cell wall. The radiolabeled precursors of lignin biosynthesis, p-coumaric acid, ferulic acid, sinapic acid, p-coumaryl- -D-glucoside, coniferin and syringin were administered to growing stems of pine, poplar and magnolia and metabolized. The distribution of silver grains on the microautoradiograms of the tissue sections revealed the following results. (1) Deposition of lignin is controlled by the individual cell. (2) Lignin is a secondary metabolite, and its mode of formation changes with the kind and age of fo the cell. (3) Deposition of carbohydrates occurs prior to deposition of lignin. This means that the polymerization of lignols occurs in the carbohydrate gels. (4) Different kinds of hemicelluloses are formed in different stages of cell wall differentiation. The kind of monolignol changes also with the stage in the order; p-coumaric acid, ferulic acid, p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. These facts cause the formation of lignin in the cell corner and middle lamella in early stage which is different in structure from the lignin formed in the seconary wall in later stages. (5) In angiosperm, guaiacyllignin deposits mainly in the vessel walls which lignify in early stage of xylem differentiation, while syringyl lignin deposits in fiber walls in later stages. (6) p-Hydroxybenzoic acid in poplar lignin is formed in every stages of xylem differentiation.
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