Reversal of the Petal Senescence Process and Ethylene Responses in Carnations

During senescence, carnation flowers show a typical response characterized by petal inrolling, and autocatalytic ethylene production. It has been generally thought that the senescence process in carnation flowers is irreversible once the tissues have entered the climacteric phase. While petal tissues have a lower sensitivity to ethylene in the preclimacteric phase, these tissues are converted to the climacteric phase at a critical point during flower development. The conversion of preclimacteric petals to climacteric phase also can be induced by exposure of the petals to exogenous ethylene. Here, we show that the senescence initiated by exogenous ethylene is a reversible process in carnation petals. We took a molecular approach to explore the genes involved in the conversion of the petals to climacteric phase. We also characterized the relationship between ethylene sensitivity and petal senescence by monitoring petal inrolling and recovery patterns. Our results show that petals treated with ethylene for 12 h exhibited sustained inrolling, while the petals treated with ethylene for 10 h exhibited inrolling followed by recovery from inrolling. We will describe the expression levels of specific gene family members in ethylene signaling and ethylene biosynthesis that were altered at the transition point from preclimacteric to climacteric phases.