Development of 3D leaf shape: utricularia gibba as a model system

Bushell, Claire (2016) Development of 3D leaf shape: utricularia gibba as a model system. Doctoral thesis, University of East Anglia.

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The development of diverse organ shapes involves genetically specified growth patterns which may differ across a tissue in rate and/ or orientation. Understanding specified growth is not intuitive since observed (resultant) growth rates and orientations are the result of specified growth combined with the effects of mechanical constraints in a connected tissue. Growth dynamics in leaves of Arabidopsis have previously been studied experimentally and modelled using a polarity field to orient growth, and regional factors which control local specified growth rates parallel and perpendicular to the polarity. It is unclear whether the mechanisms invoked for the development of 2D leaf shape can be applied to more complex 3D leaf shapes. In this work, I developed Utricularia gibba as a new model system and studied the development of U. gibba 3D epiascidiate (cup-shaped) leaves (known as bladders). I investigated bladder shape changes through development and modelled these transitions using isotropic (equal in all directions) or anisotropic (preferentially in one orientation) specified growth, showing that specified anisotropy is required to generate the full mature bladder shape. The shape of the main body of the bladder could be accounted for by both specified isotropic or anisotropic models. I tested predictions on growth dynamics and polarity made by each model using sector analysis and by investigating markers of tissue cell polarity in bladders. Sector analysis supported an anisotropic specified growth model, while quadrifid gland and UgPIN1 analysis provided evidence of a polarity field in U. gibba. Together, these observations suggest a common underlying mechanism for the generation of 3D and 2D leaves. This work shows how computational modelling can be combined with experimentation in a biological system to allow for a better understanding of the specified growth patterns underlying the generation of an organ shape.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Users 4971 not found.
Date Deposited: 13 Jun 2017 13:58
Last Modified: 13 Jun 2017 13:58

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