The use of lanthanum to characterize cell wall permeability in relation to the freezing response of woody plants

Abstract

In woody plants, tissues displaying freeze tolerance respond to low temperature by the rapid loss of cellular water to extracellular ice whereas tissues exhibiting freeze avoidance exhibit deep supercooling in which case cellular water is isolated from the dehydrative and nucleating effects of extracellular ice. Biophysical data on cells that exhibit deep supercooling has led some authors to speculate that the structure and size of pores in cell walls would play an integral role in imparting a barrier to water movement and spread of ice. Distribution of the apoplastic tracer, lanthanum nitrate, was examined in stem tissues of several species of woody plants using a transmission electron microscope (TEM) in order to acquire data on general permeability of cell walls in species that deep supercool (P. persica, C. florida, B. lenta) vs. those that exhibit extracellular freezing (S. babylonica, B. papyrifera).