Effect of temperature on ion efflux properties of leaf cell compartments in several chilling-sensitive and chilling-insensitive crop plants

Abstract

Ion efflux properties of leaf cell compartments were compared in several chilling-sensitive and chilling-insensitive plants : corn (Zea mays L. cv. Orla-312), cotton (Gossypium hirsutum L. cv. Stoneville-213), rice (Oryza sativa L. cv. M-9), spinach (Spinacia oleracea L. cv. Monnopa), and winter wheat (Triticum aestivum L. cv. Zenith). The effect of photoperiod and temperature (in spinach) and cold acclimation (in wheat) during growth on the subsequent response of cell compartments to temperature was also studied. Leaf strips loaded with Na+ (22Na) (all plants) and K+ (86Rb) (wheat only) were subjected to temperatures of 22, 15, 11, 7, and 3 °C to test efflux of tracers from various cellular compartments. When grown under identical conditions, compartmental absorption and efflux of tracers were different in corn, cotton, rice, spinach, and wheat. Changes in pretest growth conditions (in wheat and spinach) altered the uptake and efflux of tracers by leaf cells. The efflux data show that (i) the fast (free space?) compartment is temperature sensitive in several plants and (ii) not all compartments of every chilling-sensitive plant show increased leakiness at lower temperatures. Photoperiod (but not temperature) in spinach and cold acclimation in wheat were the factors that markedly altered efflux properties of cell compartments during growth. These observations are not fully consistent with models explaining chilling injury based on occurrence of cracks or pores in leaf cell membranes at lower temperatures. An alternative view based on built-in membrane channels is presented.