About the Cover
In Arabidopsis, the switch from the vegetative to the reproductive phase of growth depends on the activity of LEAFY (LFY) and other floral meristem identity genes. Gibberellins (GAs) are also thought to influence this developmental switch because mutants with severe defects in GA biosynthesis do not flower under short days. On pages 791-800, Blazquez et al. explore the link between LFY activity and GA deficiency. As they show on the cover, LFY promoterdirected ß-glucuronidase activity (pale blue) can be detected in leaf primordia in wild-type Arabidopsis stem apices; moreover, this activity increases markedly in those primordia that will develop as flowers. This pattern is disrupted in transgenic GA-deficient mutants, in which the inability to flower correlates with a significant decrease in the activity of the LFY promoter. Further evidence that GAs play a functional role in LFY activation comes from experiments showing that the constitutive expression of LFY in the GA biosynthetic mutants can restore their ability to flower.
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Copyright © 2007 by the American Society of Plant Biologists
