INVESTIGADORES
ARIEL Federico Damian
congresos y reuniones científicas
Título:
Cytokinin activation of MtRR4, a Response Regulator associated to symbiotic nodulation, is dependent on a B-Type RR DNA-core binding motif.
Autor/es:
ARIEL, FD; PLET, J; CHAN, RL; CRESPI, M; FRUGIER, F
Lugar:
Puerto Vallarta
Reunión:
Conferencia; 4th International Conference on Legume Genomics and Genetics; 2008
Institución organizadora:
Grain Legumes Integrating Project
Resumen:
Cytokinin phytohormones are crucial
for the regulation of legume root architecture, controlling both lateral root
formation and the early stages of symbiotic nodule organogenesis. Cytokinin
signalling is mediated by a multiple step phosphorelay pathway leading to the
transcriptional activation of Type-A response regulators (RRs). Type-B RRs,
which contains a MYB-type DNA binding domain, have been shown in Arabidopsis
to act as transcription factors (TFs) directly activating these Type-A RR
primary response genes. Previous work done in Medicago truncatula revealed that expression of specific members of
these families (MtRR1 and MtRR4, respectively) was associated to the symbiotic
nodulation process (1).
In this work, we expressed in Escherichia
coli and purified by affinity chromatography a GST fusion of the Type-B
MtRR1 binding domain. Seven rounds of PCR assisted binding site selections
(SELEX) revealed a 12bp consensus binding sequence, similar to a smaller DNA
core typical of MYB-type TFs. Four SELEX-like boxes were detected in the Type-A
MtRR4 promoter region, and the functionality
of these boxes in relation to cytokinin activation was determined based on a
combination of ProMtRR4:GUS
fusions, deletion and site-specific mutagenesis. The involvement of this
regulatory module in the nodulation process was also determined. In addition, a
full genome in silico approach
allowed identifying several other putative MtRR1 target genes which are
currently under validation. Remarkably, an extended region around the
SELEX-like boxes was highly conserved in their promoters.
(1) Gonzalez-Rizzo et al., Plant Cell,
2006, 10:2680-93.