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Abstract Detail



Advances in Modelling Plant Development

Holloway, David [1].

Chemical patterning dynamics in conifer cotyledon formation.

In contrast to the one or two cotyledons (seed leaves) seen in angiosperm embryos, many conifers have multiple cotyledons which form in a whorl on the domed embryo. The number can be quite variable (frequently from 2 to 12) within species and even within clonal lines. This indicates a developmental mechanism in conifers which dynamically selects cotyledon number, rather than the fixed outcomes seen in angiosperms. Experimentally, we have found that cotyledon number is proportional to embryo diameter (for several different conifer species), indicating an underlying patterning mechanism that produces constant spacing. Disrupting flow of the hormone auxin disrupts cotyledon formation, resulting in cup shaped embryos. This indicates that the chemical patterning, and the growth it induces, has two components – one involved in tip flattening, and one spacing cotyledons in the whorl. Reaction-diffusion (RD) models provide a theoretical framework for quantifying chemical patterning dynamics. For plant morphogenesis, RD must be coupled with growth dynamics, both for the effect of patterned growth catalysts on shape change and for the effect of shape change on chemical patterning. We have developed a two-stage RD model which catalyzes growth, in order to characterize the constraints on patterning kinetics and growth rates involved in cotyledon morphogenesis. The 1st stage forms a tip-flattening ring pattern; the 2nd stage forms the higher frequency cotyledon pattern within this. Loss of transport in the 2nd stage produces a ring pattern and a cup shaped surface (as in auxin-disruption experiments). The modelling indicates particular classes of kinetics (e.g. substrate depletion, activation/inhibition) which are more likely for the conifer developmental sequence. We are now adding polar auxin transport to the modelling framework, to characterize how auxin dynamics for conifer cotyledon spacing in a whorl may differ from the simpler dicot case of Arabidopsis.


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Related Links:
Holloway research site


1 - British Columbia Institute of Technology, Mathematics, 3700 Willingdon Ave., Burnaby, BC, V5G3H2, Canada

Keywords:
Conifer
spruce
modelling
auxin
Development
embryo
cotyledon
reaction-diffusion
pattern formation
morphogenesis.

Presentation Type: Symposium Presentation
Session: SY10
Location: Salon 13/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 4:15 PM
Number: SY10007
Abstract ID:577
Candidate for Awards:None


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