Abstract
Callus induction, subculture and shoot formation were investigated using barnyardgrass seeds. Relatively high levels of 2, 4-D (2×10-5M or 4×10-5M) were required for the callus induction. The callus cultures were white or yellow in color and often altered black brown under the prolonged cultivation. Hetero-geneous tissues of the cultures were remarkable in comparison with rice cultures: The higher kinetin were added to the medium, the more shoots were formed from the callus cultures. For electron microscopy the cells of callus tissues were fixed by glutaraldehyde and osmium tetroxide, and embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate and examined with Hitachi HU-12 A microscope. Many of osmiophilic granules were seen in the proplastids. Secondary vacuoles containing cyto-membranes were often observed in the callus cells. In the green regions of cultures, amyloplasts containing the large granules of starch and chloroplasts were seen. The peripheral reticulum was indicated in immature chloroplasts. It was also confirmed that mature chloroplasts have lamellar structure and multilayered grana and chloroplast-DNA filaments are occurred in some regions of the matrix having low electron density.
