Accroissement de la résistance au froid (jusqu'à −30 °C) de plantules de Blé avec un milieu cryoprotecteur. Effets de ce traitement sur les ultrastructures de cellules parenchymateuses d'ébauches foliaires

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Abstract
Wheat seedlings treated with a frost-protecting medium containing a mixture of glycerol, dimethyl sulfoxyde, and saccharose, were subjected to cooling at the rate of 1 °C/min during a few hours. Seedlings treated in this way were resistant to temperatures of −30 °C. However on rewarming, the growth of leaves and coleoptiles was slightly slowed down compared with that of control seedlings.Seedling impregnation with the frost-protecting medium provoked few ultrastructural changes in the parenchyma cells of leaf primordia. Only lipidic, osmiophilic globules were relatively abundant, and these were scattered in the peripheral cytoplasm, along the plasmalemma. Cooling to −30 °C tended to make certain organelles migrate preferentially towards peripheral regions; the plasmalemma, osmiophilic globules, microtubules, and mitochondria came into contact with each other. In spite of the very cold temperature, some mitotic figures persisted with no evident signs of changes.On rewarming the seedlings, the various changes observed during cold treatments gradually diminished and disappeared. [Journal translation]