The Morphological development of the flowers of Theobroma cacao: a comparison to other flowering spe

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The Morphological development of the flowers of
Theobroma cacao a comparison to other flowering
species

• JD Swanson
• Huck Institute of Life Sciences

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Why Flowers in cacao?

• Economic Reasons
• Initial organ that gives rise to pods
• Early initiation to speed up production
• C. perinicosa reverts floral meristems to
  vegetative ones
• Biological Reasons
• To understand the fundamental mechanisms of
  floral initiation in cacao
• Formation of staminodes
• Califlorius nature of T.cacao flowers

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ABC Model in flowers
A genes give Sepals A and B Genes give Petals B
and C genes give Anthers C genes give Carpels
B
A
C
S P A C
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Why study the morphology?

• It has been stated that in order to make use of
  molecular tools to describe the complex pathways
  of floral development it is a prerequisite to
  identify in detail the morphological development
  of the flower in question (Brukhin et al. 2003).
  This involves building a base of morphological
  and cytological definition of distinct key
  morphological events that play out in the
  development and growth of the flower organ in
  question.

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Compare Genes across species with the
morphological context in mind
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Flower Structure
Structure of 5 free sepals 5 Free Petals 10
Stamens 5 Staminodes 5 Fertile
stamens 5 United Carpels
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Methods (Simplified)

• Collected Time lapse data
• This was to correlate Bud length and width with
  time
• Collected electron and light micrographs at
  various developmental stages
• Correlated development of organs with overall
  growth of the bud

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Time Lapse
Buds taken from many flower cushions on the
tree Curves overlap indicating that there
is no real discrepancy in flower growth c.f.
placement on tree Also looked at time, No
real discrepancy in time either
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Time Lapse
Final Growth curves for - Length - Width
- Pediole
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Time Lapse
Created Residuals From Lowess curves Created an
r2 value To check fit 0.96
Have a way to relate time with bud length and
width
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Microscopy
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Microscopy

• Was able to create Growth models from
  measurements (C.f to Bayer data)

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Can talk about flower development
Androecium
Meristem
Petals and Sepals
Gynoecium
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Comparison to Arabidopsis
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Other Species
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What have we learned?

• Taken a Species with relatively little data and
  gotten it ready for molecular studies now that we
  understand the morphological norm
• Have prediction models of organs
• Have some idea of the benchmark events across
  species

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What is next?Now that we have a solid
morphological base to work of we can study

• Leafy gene
• Leafy controls floral meristem development
• We are currently in the process of
• Obtaining the full length sequence
• Seeing if the cacao gene can work in Arabidopsis
• In situ analysis to see where it is located in
  cacao flowers
• Microarray analysis
• An attempt to correlate our morphology models to
  gene data

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Acknowledgements

• My committee
• Mark Guiltinan
• John Carlson
• Hong Ma
• Francesca Chiaromonte
• The Guiltinan Lab
• The EM Facility