Ethylene and 1-Aminocyclopropane-1-Carboxylic Acid as Indicators of Chilling Sensitivity in Various Plant Species

Abstract

The release of ethylene after warming leaves of plant species which had been stored at 0°C was found to be a good indicator of incipient chilling injury. Ethylene evolution was maximal around the onset of visible symptoms, and was prevented by serious chilling damage. The duration of chilling required to induce ethylene production varied from about 1 h in the very chilling-sensitive tropical herb Episcia reptans to days in cucumber and various species of tropical passionfruit. In a series of six passionfruit species, ranking for chilling sensitivity indicated by ethylene release agreed with their known relative sensitivity to chilling. The compound 1-aminocyclopropane-1-carboxylic acid (ACC), which is the immediate metabolic precursor of ethylene, was accumulated during the chilling treatment, and continued to accumulate after warming the leaves to 20°C. The rate of accumulation of ACC during chilling also depended on the sensitivity of the species to chilling, but was not reduced by severe chilling as was the release of ethylene. The level of hydrogen peroxide, which could provide a source of oxidant for the breakdown of ACC to ethylene, did not change significantly during chilling. The results indicate that ethylene and ACC are sensitive indicators of chilling stress. ACC production suggests a possible method for the selection of chilling-resistant genotypes among crop plants.