PLANT PHYSIOLOGY , Vol 102, Issue 3 1033-1036, Copyright © 1993 by American Society of Plant Biologists
Demonstration of a Senescence Component in the Regulation of the Mannopine Synthase Promoter
V. M. Ursin and C. K. Shewmaker
Calgene Inc., 1920 Fifth Street, Davis, California 95616
Regulation of the mannopine synthase (mas) promoter during senescence in
leaves and flowers of tobacco (Nicotiana tabacum) plants was investigated.
In plants transformed with a mas 5[prime]-[beta]-glucuronidase (GUS)-mas
3[prime] transcriptional fusion, we observed that following the onset of
senescence in either intact or excised leaves of the transgenic lines, GUS
activity increased significantly, whereas in excised leaves in which the
senescence process was inhibited, GUS activity increased only marginally.
During flower petal senescence in the transgenic tobacco, GUS activity
increased approximately 6-fold over preanthesis- and anthesis-stage
flowers.