Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Mazie, Abigail [1], Baum, David [2].

Understanding cell shape diversity: the evolution of stellate trichomes in Physaria (Brassicaceae).

A central goal of evolutionary biology is to understand the genetic and developmental underpinnings of morphological variation. While much progress has been made at the tissue and organ level, the evolution of cell shape is still poorly understood. Our research aims to identify the molecular changes that have led to the evolution of cell shape using the single-celled trichomes of the mustard family, Brassicaceae, as a model. Plant trichomes are epidermal hair cells that have an adaptive role in defense from herbivores and protection from excessive solar radiation and desiccation. The genus Physaria (tribe Physarieae) displays elaborate stellate (star-shaped) trichomes that evolved from a dendritic (tree-shaped) ancestral condition. The ancestral, dendritic shape is also seen in the model species, Arabidopsis thaliana. We used the wealth of information available from studies of A. thaliana trichome development to identify two intriguing candidate genes for trichome shape evolution, STICHEL (STI) and BRANCHLESS TRICHOME (BLT). Both genes are involved in A. thaliana trichome branch initiation, and we hypothesize that the evolution of stellate trichomes in Physaria entailed changes in the expression or protein function of STI and BLT homologs. Concordant with this hypothesis, Physaria homologs of both genes show accelerated evolution and elevated dN/dS ratios. To further test this hypothesis, we are using bidirectional, interspecific transformation experiments. We will present data on the status of these interspecies transformation experiments, along with comparative developmental analyses of dendritic and stellate trichomes.

Broader Impacts:

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

Keywords:
Brassicaceae
trichome development
trichome evolution
Physarieae
STICHEL
BRANCHLESS TRICHOME.

Presentation Type: Oral Paper:Papers for Topics
Session: 47
Location: Jasperwood/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 3:45 PM
Number: 47009
Abstract ID:331
Candidate for Awards:Katherine Esau Award