Effect of Cold Acclimation on Intracellular Ice Formation in Isolated Protoplasts

Abstract

When cooled at rapid rates to temperatures between -10 and -30°C, the incidence of intracellular ice formation was less in protoplasts enzymically isolated from cold acclimated leaves of rye (Secale cereale L. cv Puma) than that observed in protoplasts isolated from nonacclimated leaves. The extent of supercooling of the intracellular solution at any given temperature increased in both nonacclimated and acclimated protoplasts as the rate of cooling increased. There was no unique relationship between the extent of supercooling and the incidence of intracellular ice formation in either nonacclimated or acclimated protoplasts. In both nonacclimated and acclimated protoplasts, the extent of intracellular supercooling was snimlar under conditions that resulted in the greatest difference in the incidence of intracellular ice formation-cooling to -15 or -20°C at rates of 10 or 16'C/mitute. Further, the hydraulic conductivity determined during freeze-induced dehydration at -5°C was similar for both nonacclimated and acclimated protoplasts. A major distinction between nonacclimated and acclimated protoplasts was the temperature at which nucleation occurred. In nonacclimated protoplasts, nucleation occurred over a relatively narrow temperature range with a median nucleation temperature of -15°C, whereas in acclimated protoplasts, nucleation occurred over a broader temperature range with a median nucleation temperature of -42°C. We conclude that the decreased incidence of intracellular ice formation in acclimated protoplasts is attributable to an increase in the stability of the plasma membrane which precludes nucleation of the supercooled intracellular solution and is not attributable to an increase in hydraulic conductivity of the plasma membrane which purportedly precludes supercooling of the intracellular solution.It is commonly observed that the incidence of intracellular ice formation is a function of the cooling rate. As early as 1886, observed that rapid cooling resulted in intracellular ice formation whereas during slow cooling ice crystals were confined to extracellular spaces. Similar rates; and the higher the permeability to water, the lower the probability of intracellular ice formation. Further, because the deplasmolysis time of cells in cold hardy tissues was less than that for cells in nonhardy tissues, they inferred that water permeability increased following cold acclimation and that the incidence of intracellular ice formation would be less in acclimated tissues. In 1938, Siminovitch and Scarth (23) experimentally demonstrated that intracellular ice formation occurs less frequently in hardy tissues than nonhardy tissues when cooled at comparable rates. They too attributed this difference to the purported increase in water permeability of the plasma membrane following cold acclimation as proposed by Levitt and Scarth (10). Although this concept has been widely accepted and frequently cited, direct experimental verification of an increase in water permeability following cold acclimation has been...

Freeze-Thaw Stress: Effects of Temperature on Hydraulic Conductivity and Ultrasonic Activity in Ten Woody Angiosperms

“…"frost fatigue" in ChristensenDalsgaard and Tyree, 2013), but this would have resulted in a translated curve (similar slope and higher T 50 ). Here, the curve showed a gentler slope and lower T 50 , which may indicate cold acclimation (Dowgert and Steponkus, 1983). Hydraulic acclimation has not previously been observed (Charra-Vaskou et al, 2012).…”

Plasma Membrane Lipid Alterations Associated with Cold Acclimation of Winter Rye Seedlings (Secale cereale L. cv Puma)

“…Severe freeze-induced de-hydration results in lamellar-to-hexagonal,, phase transitions in the plasma membrane of NA protoplasts but not ACC protoplasts (13). Also, the temperature at which intracellular ice formation occurs in NA and ACC protoplasts is substantially different (9) and is related to mechanical failure of the plasma membrane. In addition, cold acclimation alters the electrical characteristics ofthe plasma membrane and increases the critical membrane potential that results in electroporation of the plasma membrane (44).…”

Dynamics of membrane exchange of the plasma membrane and the lysis of isolated protoplasts during rapid expansions in area

“…[Further, the available evidence suggests that, in suspension at isotonic, there is little difference between the radii of acclimated and nonacclimated protoplasts and that there is not a very large difference in L~, (Dowgert & Steponkus, 1983). Thus the different tensions generated are primarily the result of different intrinsic dynamical properties of the membrane (M and Fi).l Because the incorporation rate is much higher for acclimated cells than for nonacclimated cells at all values of 3, (i.e., M is larger for acclimated cells) the maximum tension to which the membranes of acclimated cells are exposed is lower than that which occurs in the membranes of nonacclimated cells exposed to the same expansion 9 After the maximum tension is reached, it declines very slowly.…”