Proceedings
of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress
Giardini
Naxos, Italy - 18/21 September, 2002
ISBN 88-900622-3-1
Poster
Abstract - 5.01
CLONING A PLANT (GA/TC) BINDING FACTOR
SUPPORTS AN INTRON MEDIATED MODEL FOR PLANT HOMEOBOX GENE REGULATION
Santi L.*, Stile
M.R.*,**, wang Y.*, MULLER K.*, roig C.*, MULLER J.*, POZZI C.***,
RODHE W.*, Filippone E.**, Salamini F.*
*) Max-Planck-Institute fur Zuchtungsforschung,
Carl-von-Linnè-Weg 10, 50829 Koeln, Germany
**) Department of Soil, Plant and
Environmental Sciences, School of Biotechnology Sciences, Via Università
100, 80055 Portici, Italy
***) Parco Tecnologico Padano, Via Hausmann
c/o DIPROVE-UNIMI, Via Celoria, Milano, Italy
barley, homeotic genes,
transcriptional factor, development mutans
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 anectopic expression of Bkn3 in the lemma of the barley
mutant flower. In order to understand the mechanism of this regulation, the 305
bp 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 bp 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.