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Plant development and evolution: Lessons learned from candidate genes

Piazza, Paolo [2], Tsiantis, Miltos [2].

Evolution of leaf development programmes.

A key problem in developmental biology is to understand the basis for the generation of different organismal forms. Angiosperm leaves offer an attractive opportunity to study this problem as they demonstrate an enormous degree of morphological diversity. The object of our research is to study one of the most striking variants of leaf architecture, the dissected (compound) leaf. In dissected leaves the leaf blade is divided into distinct units (leaflets) unlike simple leaves where the leaf blade is entire. Both dissected and simple leaves arise from the differentiation of cells derived from an indeterminate structure termed the shoot apical meristem (SAM). SAM establishment and maintenance requires the activity of KNOTTED1-like homeobox (KNOX) proteins (1). In species with simple leaves (e.g. maize or Arabidopsis thaliana), KNOX transcripts are excluded from leaves and confined to meristematic areas. In contrast, in many dissected leaf plants KNOX expression persists within leaves (2). This expression pattern, in combination with the increased leaf dissection obtained by overexpressing KNOX genes in tomato (3), has led to the suggestion that differential regulation of KNOX gene expression may be responsible for the generation of dissected leaf morphology. However the precise role of KNOX genes in generating leaf dissection is unclear as effects of loss of KNOX gene activity in dissected leaf plants have yet to be reported. It is also unclear what other components of shoot development pathways are responsible for generating the dissected leaf form. Here we will report progress in understanding how the KNOX developmental pathway functions to generate leaf dissection.

1 - University of Oxford, Department of Plant Sciences, South Parks Road, Oxford, OX1 3RB, United Kingdom
2 - University of Oxford, Department of Plant Sciences, South Parks Road, Oxford, OX1 3RB, United Kingdom

leaf architecture
leaf development.

Presentation Type: Symposium
Session: 54-1
Location: Ballroom 1 (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 1:15 PM
Abstract ID:120

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