Effect of limiting oxygen supply on the ultrastructure of root tip cells in the germinating stage of rice [Oryza sativa] seeds
1998
Hayashi, S. (Tokyo Univ. of Agriculture (Japan). Agricultural Junior Coll.)
Root tips excised from rice seeds germinated aerobically and anaerobically for 12, 18, 24, 48, and 72 h were used as experimental materials, and the changes in the ultrastructure of the plerome cells of root tip over the passage of germination time were observed using a transmission electron microscope. The mitochondria in aerobic cells had more cristae than those in anaerobic cells from the early stage of germination. Both rough and smooth endoplasmic reticulum (ER) occurred in the cytoplasm of root cells. The most obvious developmental changes took place after 18 h of aerobic germination and after 48 h in the case of anaerobic germination. At the beginning of development, ER indicated expansion from the cisterna, after which it changed into flat form. Polysome formation was promoted during aerobic germination. Golgi bodies were developed during aerobic germination. Lipid bodies disappeared after 48 h in aerobic cells, however, they were still present after 72 h of anaerobic germination. The accumulation of starch into plastids occurred only in aerobic cells. Based on the above results, it is suggested that developments in the ultrastructure of root tips have some connection with metabolic activity in the root during the germinating stage when there is a limited oxygen supply
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