Research
Shoot apical meristem and leaf development in ferns
Ferns are a diverse group of vascular plants with a great deal of morphological variation in shoot and leaf architecture. Understanding the morphogenesis and structure of the apical meristems of ferns is necessary in order to understand organ evolution and to generate a basic working model for fern development. This can provide a framework for comparative developmental studies that will be central to developing and testing theories of land plant morphology and evolution. The aim of this study is to investigate and comprehensively document the cellular patterns of shoot meristems and leaf primordia across a number of fern species. We hope to provide key developmental information relevant not only to ferns and their closest relatives, but also to provide a comparative foundation for the formulation of developmental models of vascular plant morphology. |
Meristem structure and organization in gymnosperms
Understanding the apical meristem and its developmental influence on the sporophyte has always been a particular goal of plant morphologists. Much of our understanding of meristem structure and organization comes from angiosperms, yet little is known of the gymnosperm meristem form. In this study we examined over 70 species of gymnosperms from all 4 lineages, cycads, Ginkgo, conifer and Gnetales in order to encompass the full diversity and variation in gymnosperm meristems. We found that the growth of the meristem operates within a predictable cellular framework that generates a pattern consistent for all gymnosperms and allows meristem structure to be predicted based on size and shape. The model proposed shows that meristem size and shape is a flexible character and that variation in cellular patterns across different gymnosperms appears related to meristem geometry with little correlation to phylogenetic relationships. |
The role of LEAFY in maintaining stem cell activity in the model fern Ceratopteris richardii
Understanding how genes evolve to promote innovation is a key question in the study of evolution and development. Flowers represent a classic example of evolutionary innovation, one that propelled angiosperms into one of the most notable adaptive radiations of all times. LEAFY (LFY) is a key regulator of flower meristem identity, controlling flower organ identity gene expression in all angiosperms examined. LFY homologs have been found across land plants and in their closest algal relatives, and the conservation of LFY throughout land plants suggests that LFY must have important ancestral function(s) outside of flower development, but relatively little is known about what these might be. Together with Andrew Plackett and Jane Langdale (University of Oxford), this project examines LFY function in the model fern Ceratopteris richardii. |
Petal development in Aquilegia
The model plant Aquilegia produces elongated, three-dimensional petal spurs that fill with nectar to attract pollinators. The petal spur is a valuable system to investigate the interacting roles of cell division and cell elongation to produce complex three-dimensional organs. Transcriptomic studies on the petal spur revealed the upregulation of a known response transcription factor to the plant hormone Brassinosteroid (BR). In Arabidopsis and rice, brassinosteroids have been shown to regulate a wide range of developmental processes, including cell elongation. These data suggest that BR signaling may play a critical role in the switch from cell division to cell elongation that leads to the formation and length of the petal spur in Aquilegia. In this study we are investigating the role of AqBEH4 in the Aquilegia petal spur using a combination of gene expression studies, hormone applications and gene silencing. |