Journal Article

Quantitative Developmental Analysis of Homeotic Changes in the Inflorescence of <i>Philodendron</i> (Araceae)

Denis Barabé, Christian Lacroix and Bernard Jeune

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 101, issue 7, pages 1027-1034
Published in print May 2008 | ISSN: 0305-7364
Published online March 2008 | e-ISSN: 1095-8290 | DOI: https://dx.doi.org/10.1093/aob/mcn031
Quantitative Developmental Analysis of Homeotic Changes in the Inflorescence of Philodendron (Araceae)

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

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Background and Aims

The inflorescence of Philodendron constitutes an interesting morphological model to analyse the phenomenon of homeosis quantitatively at the floral level. The specific goals of this study were (1) to characterize and quantify the range of homeotic transformation in Philodendron billietiae, and (2) to test the hypothesis that the nature of flowers surrounding atypical bisexual flowers (ABFs) channel the morphological potentialities of atypical bisexual flowers.

Methods

Inflorescences of P. billietiae at different stages of development were observed using SEM. The number of appendices in male, female and sterile flowers were counted on 11 young inflorescences (5–6 flowers per inflorescence). The number of staminodes and carpels on ABFs were counted on 19 inflorescences (n = 143). These data were used for regression and ANOVA analyses.

Results

There was an average of 4·1 stamens per male flower, 9·8 carpels per female flower and 6·8 staminodes per sterile male flower. There was an average of 7·3 floral appendices per atypical flower. Staminodes and carpels are inserted on the same whorl in ABFs. A negative exponential relationship was found between the average number of staminodes and the number of carpels in ABFs. If only the ABFs consisting of less than six carpels are considered, there is a linear relationship between the number of carpels and the average number of staminodes. The value of the slope of the regression equation indicates that on average, in P. billietiae, 1·36 carpels are replaced by one staminode.

Conclusions

In P. billietiae, the number of appendages in female flowers imposes a constraint on the maximum total number of appendages (carpels and staminodes) that can develop on ABFs. The quantitative analyses indicate that the average number of different types of floral appendages on an ABF and the number of organs involved in a homeotic transformation are two independent phenomena.

Keywords: Philodendron; positional information; gradient; flower; homeosis; developmental constraint

Journal Article.  5383 words.  Illustrated.

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

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