New perspectives on conventional ideas about root system architecture and morphology
Open Access
- Author:
- Hanlon, Meredith
- Graduate Program:
- Plant Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 03, 2017
- Committee Members:
- Kathleen Marie Brown, Dissertation Advisor/Co-Advisor
Kathleen Marie Brown, Committee Chair/Co-Chair
Jonathan Paul Lynch, Committee Member
Yinong Yang, Committee Member
Gabriele Brigitte Monshausen, Outside Member - Keywords:
- auxin
phosphorus
lateral roots
roots
rice
root hairs - Abstract:
- Roots grow outwardly and downwardly into the soil to extract water and nutrients to fuel plant growth. The environment in which they grow, soil, obscures our view of them, making roots more difficult to observe and study than their verdant, above-ground counterparts. To facilitate the study of roots, scientists have developed systems to allow us to see roots, from high-tech imaging devices to simple, gel or solution based systems that are devoid of soil and the environment in which roots evolved to grow. Understanding and improving root growth will allow for the development of more efficient lines of plants. Improving plant nutrient acquisition by optimizing a root system is of increasing importance as population grows and the world is tasked with producing more food. Climate change, drought, and decreased availability of fertilizers make will continue to make this task more difficult in future years. To understand and ultimately improve root growth, scientists have simplified questions into testable hypothesis that rely on controlled conditions, repeatable experiments, and model systems. Though this has accelerated our rate of discovery, the impact of these discoveries has yet to be made in our food and agricultural systems. To have an impact beyond that of just basic discovery, an ambitious goal on its own, we must ensure that the systems that we use and the questions that we ask mimic a realistic environment and target the areas which we can improve. Work in plant biology is largely dominated by research on the model organisms, Arabidopsis thaliana, and, within that work, focused on gene discovery. As we learn more about the complexity of phenotypic control, the simple line connecting genotype to phenotype has evolved into a complex network of regulation and interaction. My research is on three independent projects. First, I examined the lateral root growth angle of the model plant Arabidopsis. Though we know much about how the primary root develops, we know little about lateral root growth and how these organs maintain outward growth. Our assumptions into this process have been drawn based upon what we know about the primary root. Second, I developed a system by which we can closely mimic the phosphorus limiting growth conditions of soil in an agar-based growth medium. This work refutes many of the discoveries made about plant phosphate responses based solely upon work using Arabidopsis. Lastly, I examined the control of root hair formation in rice. Root hair formation is a well understood process in Arabidopsis; however, my results show that these systems are not conserved in rice.