ARTIFICIAL LIGNIFICATION WITHIN UNLIGNIFIED CELL-WALLS OF POPULUS-KOREANA

To investigate the changes in cell walls caused by lignification, we tried to induce artificial lignification within unlignified cell walls and compared the differences before and after the lignification under an ultraviolet microscope and a transmission electron microscope. Soon after a poplar (Populus koreana Rehd.) was felled, differentiating xylem and phloem were cut into very small specimens, and incubated in a solution of coniferyl alcohol in a phosphate buffer. The specimens were embedded in epoxy resin, and thin and ultra-thin sections were prepared. Peroxidase activity also was examined under light and electron microscopes. Dehydrogenative products of the monolignol were observed, mostly in the phloem, in good accordance with the distribution of peroxidase activity. Ultraviolet absorption spectra of these dehydrogenative products showed an absorption maximum at 285 nm. The electron microscope revealed amorphous electron opaque materials accumulated in intercellular spaces among the phloem cells.