THE ROLE OF UBIQUITIN IN PLANT SENESCENCE AND STRESS RESPONSES

Ubiquitin is a small, highly conserved protein found in all eukaryotes . Within the cell, ubiquitin is covalently linked to substrate protein s, often targeting them for degradation via the ubiquitin pathway. Thi s pathway has been demonstrated to be required for both the bulk degra dation of cellular proteins and the targeted proteolysis of specific r egulatory proteins. There is increasing biochemical and molecular evid ence for involvement of the ubiquitin pathway in plant senescence and in response to stress. It appears that the role of ubiquitin during se nescence could be to facilitate bulk protein degradation for nitrogen recycling. In the wound response, the pathway could have a role in alt ering the overall protein profile.