XVI International Botanical Congess

When leaves senesce rubisco decreases in abundance over time, leaves yellow and abscise, the process is accelerated in response to the air pollutant ozone(O3). Ozone accelerates the normal decline in level of transcripts of photosynthetically associated genes e.g. cab, rbcS and rbcL, and the induction of senescence associated genes (SAGs) in Arabidopsis, suggesting that, at least in part, O3-induced accelerated senescence is a regulated event. Stress ethylene is induced by O3. ACC synthase, a key regulatory enzyme in ethylene biosynthesis, is part of a multi-gene family, several O3-induced ACC synthase genes have been identified from a number of species. The relationship between the induction of these genes, emission and detection of ethylene and induction of SAGs will be discussed.