Influence d'une déshydratation et d'une congélation (−196 °C) sur les ultrastructures des plantules d'Allium cepa. Étude après imprégnation métallique

Abstract

Artificial dehydration of 3-day-old seedlings of Allium cepa produces physiological and ultrastructural changes. Osmium fixation caused various alterations in dictyosomes, the endoplasmic reticulum, and the nuclear envelope. Seedling dehydration was accompanied by a lowering of the reduction capacity of various cell components. This lower reduction capacity also affected the same organelles in seed tissues. When seedlings were dehydrated, their tissues returned to a resting state, and became cold resistant. When artificially dehydrated seedlings were treated with liquid nitrogen (−196 °C), cells only underwent slight changes. These alterations were reversible both after dehydration and after freezing to −195 °C. During rehydration, the changes in cell structures and their reactivity following the osmic fixation technique were observed. [Journal translation]