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Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Mazie, Abigail [1], Baum, David [2].

Comparative Development of Physarieae (Brassicaceae) Trichomes.

A primary goal of evolutionary biology is to understand the molecular genetic basis of adaptive morphological features. Comparative analyses of the evolution of developmental pathway genes may shed light on the genetic processes that underlie morphological diversity between species.
Plant trichomes are epidermal outgrowths that may play an adaptive role in herbivore defense and/or desiccation resistance. The single-celled, non-glandular leaf trichomes of the mustard family, Brassicaceae, are a good model system for tackling evolutionary questions. Trichome form is highly variable across the family, and trichome development is well characterized in the model species, Arabidopsis thaliana.
As trichome cells grow away from the leaf surface, their primary axis (or stalk) may branch in numerous patterns. The tribe Physarieae (Brassicaceae) includes species with some of the most elaborate branching patterns in the family. These stellate(star-like) trichomes appear to have evolved from dendritic (tree-like) ancestors. An important difference between these patterns is the number of branches that emerge from the central trichome stalk. While 1-2 branches typically emerge from the central stalk of dendritic trichomes, as many as 30 branches may emerge in stellate trichomes. To understand the evolution of stellate trichomes in Physarieae, we are exploring the roles of two candidate genes that have been identified to be important for trichome branch initiation in A. thaliana - STICHEL (STI) and BRANCHLESS TRICHOME (BLT).
The results of a comparative scanning electron microscope (SEM) analysis of dendritic and stellate trichome development across members of Physarieae will be presented. This comparative data will be analyzed within the context of a phylogenetic tree of Physarieae estimated from sequences of STI and BLT. These studies will allow for comparisons to be made with the known developmental pattern of A. thaliana and may provide insight into regions of these two genes that are candidates for selection associated with the evolution of stellate trichomes.

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1 - University Of Wisconsin - Madison, Botany, 220 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
2 - University Of Wisconsin, Department Of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA


Presentation Type: Poster:Posters for Topics
Session: P
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM
Number: PEV003
Abstract ID:728

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