The enormous diversity of floral morphology exhibited by angiosperms is due to variation in many different aspects of floral development, including merosity, phyllotaxy, organ fusion, floral symmetry, floral organ identity and floral organ elaboration. The developmental genetic basis for this variability is only beginning to be explored. One question that has not been addressed is how new organ identity programs evolve. In this context, we have undertaken a study of the basal eudicot model Aquilegia (columbine) with a particular focus on modifications of floral organ identity. Aquilegia is exceptionally well suited for investigations of the evolution of floral developmental genetic pathways due to its evolutionary history, intriguing floral morphology and position as an emerging genetic model. The flowers of Aquilegia exhibit three main innovative features relative to those of the core eudicot models: morphologically distinct petaloid sepals, the petal spur with its associated nectary, and the presence of staminodia between the fertile stamens and carpels. Our previous studies suggest that the Aquilegia homologs of the core eudicot ABC class genes have undergone complex patterns of subfunctionalization and possibly neofunctionalization following Ranunculid-specific gene duplication events. We are now working to extend these studies to include targeted functional knock-downs of all of the floral organ identity gene homologs. In addition, large scale EST sequencing in Aquilegia has made it possible to apply genome-level techniques to the question of how this genus has evolved both novel floral organ types and novel organ elaborations. This continued research has the potential to advance our understanding of both the conservation of the ABC program and the mechanisms by which it has been modified over evolutionary time. In addition, continued studies of Aquilegia will facilitate its development as a new model species and allow us to move beyond an Arabidopsis-based candidate gene approach. Ultimately, the experiments described here will lay the foundation for a global approach to studying the evolution of a novel floral organ identity program.
The specific aims of this project are:
1. To analyze the functions of select floral organ identity gene homologs in Aquilegia using Virus Induced Gene Silencing (VIGS).
2. To use Illumina-based comparisons to investigate the differences between the stamen vs. staminodium and sepal vs. petal developmental programs.
3. To characterize new candidate loci derived from Aim 2 using in situ hybridization and VIGS-based functional assays.
Faye was a postdoc on an NSF-funded project
Faye completed her research in 2010 and joined the research program at the Arnold Arboretum as the Laboratory Manager of the new Weld Hill facility.
My work has been largely focused on Aims 2 and 3 above, including extensive optimization required to perform laser microdissection (LCM) of developing staminodia and stamens using the Zeiss PALM MicroBeam system. This work is now complete and we are in the process of analyzing Illumina sequencing data from both LCM captured material and homeotic mutants.
Aquilegia floral organs
LCM of Aquilegia floral primordia