Molecular aspects of leaf senescence

Senescence is the last stage of leaf development and one type of programmed cell death that occurs in plants. The relationships among senescence progr ams that are induced by a variety of factors have been addressed at a molec ular level in recent studies. Furthermore, an overlap between the pathogen- response and senescence programs is beginning to be characterized. The comp lexity of the senescence program is also evident in studies of senescence-s pecific gene regulation and the role of photosynthesis and plant hormones i n senescence regulation. New molecular-genetic approaches are expected to b e useful in unraveling the molecular mechanisms of the leaf senescence prog ram.