Plants use the sun's energy to convert carbon dioxide gas into the organic materials required for life. Key to this primary productivity is the axial extension of plant stems into the atmosphere where leaves can capture sunlight and exchange gases. The same axial growth process drives roots into the soil to find water, nutrients and a stable footing for the organism. This project is focused on elucidating the molecular mechanisms by which seed plants execute this axial growth plan at a cellular level. Seed plants have taken one of the major polymer systems found in all eukaryotic cells, the microtubules, and repurposed them as patterning agents. The plant cell creates specific patterns of microtubules just underneath the cell's membrane that act as templates for the construction of the fibrous walls created on the outside of the cell. It is the cell wall that ultimately gives the plant its structure and rigidity. The finely detailed nanofabrication of the plant cell wall underlies the ability of all seed plants to extend axially up into the sunlight or down into the soil. This work employs modern molecular genetic techniques and advanced cell biological methods in the Arabidopsis model system with the aim of discovering what genes are specifically required for organizing the microtubule arrays for axial cell growth.
Broader impacts The basic science being performed impacts several areas of practical and commercial interest. Crop plant plot density is directly dependent upon the axial growth habit (e.g. corn or soybean fields). This work will further elucidate the genes involved in mechanical extension of the hypocotyl during seed germination, a critical period in crop plant development. This work provides valuable information about plant microtubule dynamics, a common herbicide target, and the patterning of cellulose polymers in the cell wall, the major biofuels feedstock. This project provides advanced training for a post-doctoral fellow and two (sequential) graduate students. The training will include exposure to leading-edge imaging technologies and integrated mathematical modeling. At least 2 undergraduate students will be working on this project as part of their undergraduate honors thesis requirements. Specialized techniques developed for acquisition and analysis of live-cell image data are being presented as technical reports and in seminars to advance the field.
