Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Barley
            

IS BBR GOING GAGA?

¹ Max-Planck-Institute fur Zuchtungsforschung, Carl-von-Linnè-Weg 10, 50829 Koeln, Germany

² Fraunhofer IUCT - Molekulare Biotechnologie RWTH Aachen Institut für Biologie VII Worringer Weg 1 52056 Aachen

The Hooded mutation, which causes the formation of an extra flower of inverse polarity, is governed by the dominant genetic locus K that maps on the short arm of chromosome 4. This mutation has been associated with Bkn3, which belongs to the plant Knox gene family. The mutation is caused by direct duplication of 305 bp in the large intron IV of the gene resulting in an ectopic expression of Bkn3 in the lemma of the barley mutant flower. In order to understand the mechanism of this regulation, the 305 has been investigated: it can enhance, in a tissue specific fashion, the expression of a GUS reporter gene driven by a 35S minimal promoter in transgenic tobacco. Using this 305 element in a one-hybrid screen we identified a protein interactor named BBR. This protein shows homology with 3 proteins, of unknown function, present in Arabidopsis. BBR carries the DNA binding domain at the C-terminus and has a clear Q rich region at the N-terminus portion of the protein. Using in vitro binding assays we identified a stretch of (TC) 8 repeats on the element where the protein binds. Interestingly Trithorax like of Drosophila, one of the few GAGA factor cloned, is involved, together with polycomb genes, in the regulation of homeotic mutations. According to this analogy we are investigating the role of this novel plant GAGA factor in controlling plant leaf development.