Carnivorous pitcher plants are a fascinating example of adaptation to nutrient-poor soils. Remarkably, the pitcher insect trap evolved three times independently in plants. How did the pitcher evolve from a flat leaf? Did each separate evolution of the pitcher involve the same genetic changes, or do they represent completely different ways of making a similar structure? To address these questions, this study will apply genetic findings from model plants to test hypotheses of the genetic changes responsible for the evolution of the carnivorous pitcher from a flat leaf. This research will evaluate expression patterns and silencing of genes known to be involved in leaf formation and compare their role in the three groups of pitcher plants.
This research will provide research-based training for high school and undergraduate students with diverse backgrounds. Furthermore, the ability of these plants to excite public interest will aid in the communication of both scientific principles and the findings of this study through various media formats. This study has possible benefits for the application of biotechnology. The establishment of a method for silencing genes, as proposed for the study of leaf development in pitcher plants, could help advance protein harvesting technology and gene discovery in plants of agronomic importance.
Overview Carnivorous pitcher plants are a fascinating adaptation made even more fascinating by the fact that the pitcher trap evolved three times independently in distantly related flowering plants. Did each new occurrence of the pitcher involve the same genetic changes, or do they represent completely different ways to make a similar structure? This study applied genetic findings from model plants to test hypotheses of the genetic changes responsible for the origin of the carnivorous pitcher from a flat leaf. With molecular tools, this research evaluated the expression and silencing of genes of interest to help answer these questions. Advancing genetic research into carnivorous plants and their origin has possible benefits beyond basic plant biology, with implications for biotechnology and medicine. The genetic network studied here involves components promising for medical use in humans. Furthermore, the development of a method for turning off genes in a pitcher plant could help advance protein-harvesting technology and gene discovery. The ability of carnivorous plants to excite interest outside of science provided opportunities for communication of general scientific principles to the public through various media outlets. This research also involved research-based training for high school and undergraduate students with diverse backgrounds. Research Findings The main goal of this project was to find the genetic changes responsible for the evolution of the pitcher trap in carnivorous plants. This PhD dissertation research was focused around the fact that carnivorous plant traps have evolved separately multiple times in plant evolution, and all instances are structural adaptations to leaf organs. An important first step to better understand the genetic evolution of leaves was accomplished by establishing the evolutionary history of two interacting genes that control leaf development in all land plants. An expanded view of those interacting genes was then studied in the genome of the carnivorous plant Utricularia gibba. We found that specific subsets of these genes were more numerous and possibly responsible for forming the intricate trap of this species. Surprisingly, we also found a subset that may be responsible for controlling root development, a function that was previously not well understood. Another goal of the project was to produce a laboratory technique for testing the function of genes in carnivorous pitcher plants. Many experiments were carried out during this project that have helped inform ways to reach this objective. An international collaboration with a biotechnology company was forged to facilitate the development of this technique. Public Outreach This research project provided the opportunity for public education and outreach from elementary through high school to post-secondary levels as well as activities at the Florida Museum of Natural History. A presentation on plant form and function with an emphasis on carnivorous plants and a hands-on creative activity was developed for demonstration at two local elementary schools. High school students in a summer research program and multiple undergraduate college students also aided the laboratory and computational research activities of this project, thus exposing young adults from diverse backgrounds to the scientific method, biological concepts, and possible career paths.
