The cytological responses of tomato-seedling cotyledons to chilling and the influence of membrane modifications upon these responses

Abstract

Tomato seedlings were exposed to 3 days of chilling at 5 °C in both the presence and absence of 5 mM ethanolamine. An array of pathological responses could be seen at both the light and electron microscope levels: apparent loss of cell turgor, vacuolization, reduction in the apparent volume of both the cytoplasm and the vacuolar protein bodies, apparent deposition of new material in the cell walls, general disorganization of organelles, especially plastids, and a general loss of cytoplasmic structure. Chilling injury was less pronounced in ethanolamine-treated cotyledonary tissues which appeared to have normal turgor and cell shape at the light microscope level and better preserved organelles at the ultrastructural level. Protection by ethanolamine at the ultrastructural level was most pronounced for the cytoplasm, the mitochondria, and the cell walls. Dead cells were seen with both treatments but were 2–3 times as numerous in the chilled-only tissue.