Proceedings of the XLVII Italian
Society of Agricultural Genetics - SIGA Annual Congress
Verona,
Italy - 24/27 September, 2003
ISBN 88-900622-4-X
Poster
Abstract - 4.05
LEAF SHAPE IN ARABIDOPSIS RELATIVES
P. PIAZZA, M. TSIANTIS
Department of Plant Sciences, University of Oxford,
South Parks Road, Oxford OX1 3RB, UK
Arabidopsis, leaf shape, KNOX
All the above-ground organs of a plant originate from
a group of cells at the shoot apical meristem (SAM). The SAM serves two main
functions: in the central zone, a population, pluripotent stem-like cells is
maintained, and in the peripheral zone, lateral organ primordia are initiated.
In Arabidopsis, two KNOX genes,
STM and KNAT1 (KNOTTED1-LIKE
in ARABIDOPSIS THALIANA1), are expressed in partially overlapping domains of
the SAM and are redundantly required for meristem maintenance. Transcripts for
both genes, however, are excluded from leaf primordia.
Ectopic expression of STM results
in meristem formation on the adaxial surface of the cotyledons and growth arrest
[3]. Ectopic expression of KNAT1 not only results
in the formation of meristems on leaves but also triggers the development of
lobes.
Many closely related species of Arabidopsis
thaliana show serrated or lobed leaves thus phenocopying leaves
of 35S:KNAT1 plants. This has led to the suggestion that
species-specific alterations in KNOX expression
patterns result in lobed leaf forms [4].
We aim to test the hypothesis that lobed
leaves in Arabidopsis species other than A. thaliana arise as a result of KNOX expression
within the leaf and understand the mechanisms specifying persistence of KNOX
expression within leaf primordia. Comparative studies
between A. thaliana and its dissected leaf relatives should be
hugely expedited given the wealth of molecular tools available to study
development of A. thaliana.
[1] Long et al., Nature 379,
66–69 (1996)
[2] Byrne et al., Development
129, 1957-1965 (2002)
[3] Williams et al., Bioessays 20,
280–282 (1998)
[4] Bharathan et al., Science
7;296(5574):1858-60 (2002)