Journal Article

A role for <i>PHANTASTICA</i> in medio-lateral regulation of adaxial domain development in tomato and tobacco leaves

Nicholas Zoulias, Daniel Koenig, Ashley Hamidi, Sheila McCormick and Minsung Kim

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 109, issue 2, pages 407-418
Published in print February 2012 | ISSN: 0305-7364
Published online December 2011 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcr295
A role for PHANTASTICA in medio-lateral regulation of adaxial domain development in tomato and tobacco leaves

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Diverse leaf forms in nature can be categorized into two groups: simple and compound. A simple leaf has a single blade unit, whilst a compound leaf is dissected into leaflets. For both simple and compound leaves, a MYB domain transcription factor PHANTASTICA (PHAN) plays an important role in establishing the adaxial domain in the leaf. Absence of PHAN in arabidopsis and antirrhinum leaves supresses blade development, and in tomato suppresses leaflet development. However, in the rachis and petiole regions of tomato leaves where PHAN and the adaxial domain coexist, it has been unclear why leaf blade and leaflets are not formed. We hypothesized that PHAN regulates the medio-lateral extent of the adaxial domain, thereby determining compound leaf architecture.

Methods

To test this hypothesis, we generated and analysed transgenic tomato plants expressing tomato PHAN (SlPHAN) under the Cauliflower mosaic virus (CaMV) 35S promoter in both sense and antisense orientations, and tobacco plants that over-express tomato SlPHAN.

Key Results

Modulations in SlPHAN resulted in a variety of leaf morphologies such as simple, ternate and compound in either a peltate or non-peltate arrangement. Measurements of the extent of the adaxial domain along the wild-type tomato leaf axis showed that the adaxial domain is narrowed in the rachis and petiole in comparison with regions where laminar tissue arises. In antiSlPHAN transgenic leaves, no blade or leaflet was formed where the adaxial domain was medio-laterally narrowed, and KNOX gene expression was correlatively upregulated. CaMV35S::SlPHAN expression led to widening of the adaxial domain and ectopic blade outgrowth in the rachis of tomato and in the petiole of tobacco. Taken together, these results suggest that SlPHAN plays a role in medio-lateral extension of the adaxial domain and contributes to final leaf morphology in tomato.

Conclusions

This study provides a novel insight into leaf architecture in tomato and highlights how changes in the expression domain of a master regulator gene such as SlPHAN can be translated into diverse final leaf morphologies.

Keywords: PHANTASTICA; KNOX genes; compound leaf; simple leaf; homology; tomato; Solanum lycopersicum; tobacco; Nicotiana tabacum; leaf evolution

Journal Article.  7227 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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