The purpose of this project is to investigate how individual genes of a model organism, the plant Arabidopsis thaliana, contribute to its ability to survive drought conditions. As the world's population continues to climb and agricultural resources are at a premium, the need to develop crops becomes paramount. Understanding the molecular mechanisms that have evolved that enable plants to survive drought will prove to have increasing importance as global weather patterns continue to become more uncertain. Arabidopsis thaliana was selected for several reasons: 1) Its genome has been fully sequenced; 2) There are well-established stocks of mutants with individual genes knocked out or enhanced; 3) It has a rapid generation time (seed to seed); 4) Large quantities of plant materials can be grown under laboratory conditions; 5) There is a rich literature on its anatomy, physiology and its genetics; 6) It represents a class of plants that may have formed a bridge between ancestral desiccation-tolerant species and the C4 crops that are now largely responsible for feeding the world's human population; and 7) The plant body is small enough to allow the entire plant may be imaged inside an environmental scanning electron microscope. In order to gain a deeper comprehension of how water loss affects cell and cell wall deformation, the individual mechanical contributions that specific cell wall components (lignin, cellulose, xylose, fucose, arabinose, and rhamnose) make to plant survival under drought conditions will be investigated. These findings have the potential to direct future efforts in plant breeding and engineering of more drought-tolerant species.
The funding from this proposal will be used to mentor undergraduate students from Villanova University and Drexel University, as well as through a two-week summer program for local high school teachers.
Over the course of this four-year investigation, we were able to test the general hypothesis that genes responsible for growth and maintenance of plat cell wall tissue are also likely responsible for a plant's ability to survive drought, and that cell wall content and drought tolerance are likely related. We achieved this by first obtaining, then growing several genetic mutants along with controls in both fully hydrated and drought-simulating conditions. In general, we found that plants that were less likely to survive drought were typically those with compromised mechanical properties. Investigators from Villanova University, Drexel University, The University of Montana and University of Cape Capetown as well as a teacher and K12 students from the Missoula County Public School system were involved. Since the investigation was an interdisciplinary endeavor, a variety of techniques were employed including drought simulation in a greenhouse, research into the role that individual genes serve in cellulose and hemicellulose production and maintenance, general mechanics of materials theory, conductivity measurements of control and drought simulated tissue, design, construction and utiilization of a biomechannical tensile tester. We were fortunate to have a very motivated and talented team comprised of a post-doctoral fellow, several graduate students, several undergraduate students, a very bright high school student and a high school teacher. It is our hope that our work can be built upon to gain a more complete body of knowledge of how plant genetics and plant biomechanics can be used as predictors for a plant's ability to survive "Life in Transition."
