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)