First published online June 28, 2004
Development 131, 1402e (2004)
© The Company of Biologists Limited
As the days draw in
Floral initiation in Arabidopsis plants, particularly as the days
become shorter, is promoted by the phytohormone gibberellin (GA). GA overcomes
the repressive effects of DELLA proteins to allow transcription of the floral
meristem identity gene LEAFY. On
p. 3357 of this
issue, Achard et al. investigate the role of a highly conserved GA- and
DELLA-regulated microRNA known as miR159 during floral initiation. The authors
show that miR159 cleaves the mRNA transcript of a GAMYB protein called
AtMYB33. GAMYB proteins are GA-specific transcriptional regulators that
activate the transcription of LEAFY. By making transgenic
Arabidopsis plants, the researchers confirmed that overexpression of
miR159 results in the reduction in LEAFY transcript levels and
delayed flowering during short-day photoperiods. They go on to discuss a model
for the modulation of floral development by this microRNA, whereby it acts,
within a negative-feedback loop, as a homeostatic regulator of GAMYB
function.
Related articles in Development:
- Modulation of floral development by a gibberellin-regulated microRNA
- Patrick Achard, Alan Herr, David C. Baulcombe, and Nicholas P. Harberd
Development 2004 131: 3357-3365.
[Abstract]
[Full Text]