Low Temperature Affects Pattern of Leaf Growth and Structure of Cell Walls in Winter Oilseed Rape (Brassica napus L., var. oleifera L.)

Three-week acclimation of winter oilseed rape ( Brassica napus L. var. oleifera L.) plants in the cold (2 °C) resulted in a modified pattern of leaf cell enlargement, indicated by the increased thickness of young leaf blades and modified dimensions of mesophyll cells, as compared with non-acclimated tissues grown at 20/15 °C (day/night). The thickness of leaf cell walls also increased markedly during cold acclimation but it decreased in response to a transient freezing event (5 °C for 18 h followed by 6 or 24 h at 2 °C, in the dark). Cell walls of the upper (adaxial) epidermis were most affected. Their ultrastructure was modified by cold and freezing treatments in different ways, as revealed by electron microscopy. Possible reasons for the cold- and freezing-induced modifications in the leaf and cell wall morphology and their role in plant acclimation to low temperature conditions are discussed. Copyright 1999 Annals of Botany Company