First published online May 16, 2007
Development 134, 1105e (2007)
© The Company of Biologists Limited
Plant hormones get the GISt
Gibberellins (GA) and cytokinins - plant hormones - induce antagonistic
signals during leaf formation and in meristem maintenance. Both hormone
signalling pathways are required in Arabidopsis for the initiation of
their defensive epidermal structures, trichomes. GA act via the transcription
factor (TF) GLABROUS INFLORESCENCE STEMS (GIS). The downstream mechanisms by
which cytokinin signalling regulates this process are less clear. Now, Pierre
Broun's group show that the GIS-related transcription factors GIS2 and ZFP8,
but not GIS, mediate this response to cytokinins
(p. 2073). A series
of overexpression and RNAi-knockdown experiments in both wild-type and mutant
plants reveal that GIS, GIS2 and ZFP8 play overlapping roles in GA signalling,
but that GIS is dispensable for cytokinin signalling. The molecular
interactions between the two hormone signalling pathways are thus uncovered
and, interestingly, despite shared mechanisms of action, these TFs have
evolved differential responses to GA and cytokinin signalling.
Related articles in Development:
- Integration of cytokinin and gibberellin signalling by Arabidopsis transcription factors GIS, ZFP8 and GIS2 in the regulation of epidermal cell fate
- Yinbo Gan, Chang Liu, Hao Yu, and Pierre Broun
Development 2007 134: 2073-2081.
[Abstract]
[Full Text]