15th International Conference on Arabidopsis Research - TAIR

T02-041
Functional analysis of the CLE40 signal in
Arabidopsis root meristem development
Yvonne Stahl(1), Rüdiger Simon(1)
1-Institute of Genetics, Heinrich-Heine Universität Düsseldorf
Stem cell activity of the initial cells of the root meristem is controlled directly
by the adjacent cells of the quiescent centre. They maintain cells in their
neighbourhood, comparable with WUSCHEL-expressing cells in shoot- and
floral meristems. CLE40, a member of the CLE protein family, encodes a
potentially secreted protein that is distantly related to CLV3. While CLV3
transcripts are confined to stem cells of the shoot meristem, CLE40 is expressed
at low levels in all tissues, including roots. Although different in their
expression patterns, CLV3 and CLE40 are functionally equivalent proteins, as
already shown by promoter swap and misexpression experiments. High level
expression of CLV3 or CLE40 results in the premature loss of root meristem
activity and differentiation of meristem cells, indicating that activation of a
CLV-like signaling pathway may restrict cell fate also in roots. Cle40 insertion
mutants show developmental defects that are probably due to the premature
loss of stem cell activity in the root. Our aim is to study how the CLE40
signal is transmitted and which genes and functions are regulated by CLE40.
15 th <strong>International</strong> <strong>Conference</strong> on Arabidopsis Research 2004 · Berlin
T02-042
Genetic analysis of the SCABRA and RUGOSA genes
Hricova, Andrea(1), Quesada, Victor(1), Micol, Jose Luis(1)
1-División de Genética and Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de
Elche, 03202 Elche, Alicante, Spain.
We have performed a large-scale screening for EMS-induced mutants displaying
aberrantly shaped leaves in the model system Arabidopsis thaliana.
Some of the recessive mutations found were named scabra (sca) and rugosa
(rug), which cause the vegetative leaves to be rounded, with protruded
laminae and irregularities on the epidermis that may be due to the perturbation
of cell division or cell expansion. In addition, necrotic sectors are visible
on the surface of rug1 leaves, probably as a result of local processes of cell
death. Transverse sections and confocal microscopy studies revealed that
internal leaf architecture is dramatically perturbed in the sca1, sca4 and rug1
mutants, whose palisade mesophyll cells are extremely reduced in number.
Scanning electron microscopy analyses indicated that rug1 epidermal cells
are larger than the wild type ones, although they are similar in shape to those
of the wild type. We are positionally cloning the SCA and RUG genes, which
map at chromosome 2 (SCA1 and SCA3), 3 (SCA4) and 5 (SCA5 and RUG1),
respectively. We have delimited candidate regions of 1 Mb, 100 kb and 0.9
Mb, respectively, for the SCA3, SCA4 and RUG1 genes. To study genetic
interactions, the sca and rug mutants have been intercrossed and crossed to
other leaf mutants previously isolated in our laboratory. The identification and
characterization of the corresponding double mutants is in progress. Further
details of the study of sca and rug mutants will be presented at the meeting.
T02 Development 2 (Shoot, Root)