Over-expression of a chimeric gene of the transcriptional co-activator
MBF1 fused to the EAR repressor motif causes developmental
alteration in Arabidopsis and tomato
Transcriptional co-activators of the Multiprotein Bridging Factor1 (MBF1) type belong to a multigenic family that encode key components of
the machinery controlling gene expression by communicating between transcription factors and the basal transcription machinery. Knocking-down
the expression of one member of the family has proved difficult probably due to functional redundancy. We show here that a fusion of SlER24, an
MBF1 type gene of tomato, to the Ethylene-responsive element-binding associated Amphiphilic Repression (EAR) motif is capable of slowing
down significantly the expression of the GFP protein driven by a synthetic ethylene-responsive GCC-rich promoter in a single cell transient
expression system. A fusion of AtMBF1c of Arabidopsis to EAR, driven by the 35S promoter, caused a reduction of the percentage of seed
germination and dwarfism of the plant. Similar fusion with the SlER24 of tomato in the MicroTom cultivar induced a delay of seed germination and
no obvious effect on plant growth. Besides giving information on the role of the MBF1 genes in plant development, this study demonstrates that the
EAR strategy is efficient not only for regular transcription factors as demonstrated so far, but also in the case of co-activators known to not bind
directly to DNA
