XVI International Botanical Congess

The interrelationships and semi-independence of physiological and pathological routes to plant cell death will be discussed. Senescence is a component of normal development intimately associated with, but very different from, autolytic or pathological cell death. I will survey senescence of cell and tissue types and the role of organelle modifications in the symptoms of leaf senescence. Cells undergoing senescence turn on new metabolic pathways and turn off others. I will review chlorophyll catabolism, oxidative metabolism and proteolysis, focusing on new insights into regulation and subcellular organization. Genetic control of senescence will be discussed from the perspective of stay-green mutants and promoter analysis. Finally I will present recent data on reversibility, a feature of mesophyll senescence that fundamentally distinguishes it from other death processes.