Abstract:Ethylene is an important plant hormone involving in various physiological processes. Ethrel which releases ethylene in a solution of pH higher than 4.1, was used to treat the carrot protoplasts. It was found that percentage of cell death kept rising with the increase of ethrel concentration. Characteristics of apoptotic cells, such as nuclear condensation and DNA laddering were observed. Neutral comet assay which detects nuclear DNA fragmentation provided evidence that ethylene induced apoptosis in carrot protoplasts.