Skip to main content
ARS Home » Research » Publications at this Location » Publication #106251
Title: HEAT-INDUCED PROTECTION AGAINST DEATH OF APPLE FRUIT CELLS EXPOSED TO LOW TEMPERATURE

Author
item Wang, Chien
item BOWEN, J
item WEIR, I
item ALLAN, A
item FERGUSON, I

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Low temperature injury is a problem in many horticultural crops. Symptoms of low temperature injury such as pitting, discoloration, internal breakdown, and decay can result in substantial postharvest losses during marketing. Several techniques have been found to reduce low temperature injury. One of these techniques is the use of prestorage heat treatment either by hot water dip or by hot air treatment. However, the mechanism by which heat treatment exerts its effect is not fully understood. The present study showed that strong heat shock protein gene expression occurred in apple cells which had been treated with heat. The effect of heat on membrane stability and oxidative activity also played a role in the protection against death of cells. This information is helpful in understanding how the heat treatment induces low temperature tolerance. This research has potential to benefit other scientists and produce industry.

Technical Abstract: Cell death in suspension-cultured apple fruit cells (Malus domestica Borkh. cv Braeburn) resulting from exposure to low temperature (1 degree C), was reduced by a prior 1 h treatment at 38 degree C. Nonheated chilled cells produced higher levels of ethylene, indicating chilling injury, while preheated chilled cells produced lower ethylene levels. The heat treatment resulted in substantial increases in transcripts for a low-molecular weight (hsp17) and a 70kD heat-shock protein. These elevated levels of expression weakened within 24 h following subsequent transfer of cells to 25 degree C. However, when cells were instead transferred to 1 degree C following heat treatment, strong hsp gene expression persisted for as long as 3 days. Flow cytometric analysis of apple cell protoplasts experiencing the same temperature treatments showed that the 1 degree C treatment resulted in a sub-population of protoplasts undergoing cell death. This sub-population was not observed with the 38 degree C pretreatment. Chromatin condensation was less with the heat treatments, and some DNA breakdown was observed with both high and low temperatures. These results suggest that heat-induced reduction in cell death at low temperatures may involve persistence of hsps, and the effects of heat on membrane stability and oxidative activity. All cells do not respond in the same way, and sorting of resistant and susceptible populations will allow better molecular analysis of temperature tolerance.