Reversibility of Chilling Injury to Corn Seedlings

Abstract

Seedlings of corn (Zea mays) were tested for recovery from chilling injury incurred at 0.3 ± 0.3 C. At 0.3 C visual leaf injury appeared in 36 hours, whereas stem and root injuries appeared later. Appearance of leaf injury was preceded by a rise in 02 uptake and a lessened effect of 2,4-dinitrophenol on 03 uptake by leaf segments and was accompanied by increased ion leakage from the leaves. These effects were Temperatures that cause chilling injury vary with species and can be as high as 12.5 C (14). The lower the temperature and the longer the time of exposure, the more severely a plant will be injured. Extended periods of chilling are usually lethal, whereas shorter periods delay and can permanently modify growth and development of a plant. Clearly, however, some expressions of chilling injury are reversible by transfer to nonchilling temperature, at least in their early stages of development. For example, cacao seed viability is normally destroyed in 10 min at 4 C, but it will survive this exposure if quickly immersed in 37 C water (2). Likewise, respiration of chilled citrus fruits increased less when alternated between chilling and nonchilling temperatures than when held constantly at chilling temperatures (6); decreased ATP content of cotton seedlings was restored to the control level when the seedlings were returned to 30 C after 24 hr but not after 48 hr at 5 C (16); decreased ascorbate and chlorogenic acid contents in chilled sweetpotato roots were regained after 2 but not 4 weeks at 75 C (11).This reversibility of chilling injury has been commonly observed but has not been examined systematically. Little is known of the mechanism of this reversal or how much injury can be reversed or how complete the reversal is. We have conducted a series of experiments to determine the extent of chilling injury that can be reversed and the rate of this reversal, using corn seedlings as the susceptible plant material and 02 uptake, sensitivity to upcoupling of oxidative phosphorylation by DNP,' ion leakage, growth, and visual symptoms as the parameters of chilling injury. MATERIALS AND METHODSPreliminary trials showed that seedlings of Rainbow cv. of flint corn (Zea mays var. Indurata) are sensitive to chilling injury, are injured rapidly, and produce clear, characteristic visual symptoms of the injury. They, therefore, were used in all experiments. Seeds were soaked for 24 hr at room temperature and sown in flats of vermiculite. Seedlings were grown for 7 days at 21 C under continuous light of 100 to 140 ft-c and then thinned to 10 uniform plants before chilling treatments were begun. They were watered on alternate days with tap water and full-strength Hoagland's solution.In a preliminary experiment, seedlings were chilled at various temperatures for different lengths of time to determine the effective temperature range for chilling them and also to establish their development of visual injury symptoms. However, in all experiments for which data are reported here 7-day-old seedlings were chilled at 0.3 + 0....

Acclimation, Hydrogen Peroxide, and Abscisic Acid Protect Mitochondria against Irreversible Chilling Injury in Maize Seedlings

“…Chilling sensitivity has also been attributed to critical changes in membrane fluidity (Lyons et al, 1964;Lyons and Raison, 1970). Any phase changes in the inner mitochondrial membrane would have drastic effects on the orientation of the respiratory chain components with a concomitant reduction of electron flow through the Cyt chain (Creencia and Bramlage, 1971). These data support the hypothesis that the ability of the tissue to recover from these damaging temperature regimes depends on restoring electron flow to the normal Cyt pathway during recovery from chilling stress, which is evident from our recovery data.…”

Temperature-Induced Leakage from Chilling-Sensitive and Chilling-Resistant Plants

“…The increase in rate below 10 C was considerably greater for the L. hirsutum altitude variants (Fig. 4b), especially when compared to [3 H]leucine leakage from the same material (Fig. 4a).…”

“…Liebermann et aL (7) found 5 times as much potassium leakage from sweet potato roots after 10 weeks storage at chilling temperatures. There was also enhanced leakage of electrolytes from leaf tissue (3,11,19) and fruit tissue (16) at chilling temperatures. The results of Tatsumi and Murata (16) showed that fruit pitting, a symptom of chilling injury, was visible after 5 days whereas leakage did not increase until the 7th day.…”

Diurnal Changes in the Chilling Sensitivity of Seedlings

“…For example, Creencia and Bramlage (2) showed that although corn seedlings held for 36 h at 0.3°C were undamaged when returned to ambient temperatures, those held for 48 h or more were irreversibly damaged.…”