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Abstract

During postembryonic development plants undergo several dramatic phase
changes. A good example is the switch from vegetative growth to flowering.
During this event, the shoot apical meristem switches fate and starts producing
flowers instead of leaves. We have studied this process on a global scale
by expression profiling and found several genes that are highly responsive to
changes in photoperiod (Schmid et al., 2003).
Among these genes we have identified a small, plant specific family, now
called UGF, which comprises four members in Arabidopsis. Two of the UGF
genes (UGF1 and UGF2) are induced by long-day conditions while the other
two genes (UGF3 and UGF4) are repressed. We are studying in detail how the
UGF genes contribute to meristem identity and floral induction. To that end we
have been analysing the expression of the UGF genes by in situ hybridization.
The subcellular localization of the gene products is being studied by UGF:GFP
fusion proteins. We are further creating and analysing ‘loss-of-function’ and
‘gain-of-function’ alleles for all four UGF genes. In order to understand UGF
protein function, we have identified interacting proteins in a yeast-two-hybrid
screen. Preliminary data suggest that UGF genes participate in several developmental
processes, including meristem maintenance and shoot branching.
In the end we hope to integrate the UGF genes and interacting proteins in the
network of meristem maintenance and floral transition.