Project Title:
Determining gravitropic sensitivity: a mathematical approach

Project Description (short):
See below.

Skills needed:
The biology student will be expected to perform bench experiments on plant growth and imaging. The student should be a careful observer, detail oriented, well organized, reliable, hard-working, and good at or willing to learn time management in planning and carrying out experiments in a timely manner. Knowledge of plant physiology and cell biology is beneficial.

The mathematics student will be expected to use material through Calculus III and Linear Algebra, and will need to be able to use a programming language to test candidate mathematical algorithms in application.

Start Date:
January 2007

End Date:
December 2008

Mentors:
Prof. John Ma (Biology), johnma@truman.edu
Prof. Todd Hammond (Mathematics), thammond@truman.edu

Current Students:

• Bo Forrester (Mathematics & Computer Science)
• Yu-yu Ren (Biology)

Past Students:

• Chris Hassett (Mathematics & Computer Science)
• Jacob Henderson (Biology)

Accomplishments:

• Hassett, Chris and Henderson, Jacob. "The Effect of Age on Gravity Perception in Flax Roots: A Mathematical Approach." Poster at the 2007 Joint meeting of the Society for Mathematical Biology and the Japanese Society for Mathematical Biology. San Jose, California. July 31 - August 3, 2007.
• Henderson J, Hassett C, Ma Z, Hammond T (2008) The effect of age on gravity perception in flax roots: a mathematical approach. Abstract for 2008 Student Research Conference (21st Annual Undergraduate and 6th Annual Graduate Research Conference, April 3, 2008), Kirksville, MO.
• Yu-yu Ren and Bo Forrester. 'Determining the Correlation between Temporal Changes in Gravitropism and Auxin Sensitivity in Flax (Linum usitatissimum) Roots: A Mathematical Approach' Poster at annual meeting of the Society for Mathematical Biology. Fields Institute, University of Toronto, Canada. July 2008.
• Ren Y, Forrester B, Ma Z, and Hammond T "Determining the Correlation between Age-related Changes in Gravitropism and Auxin Sensitivity in Flax (Linum usitatissimum) Roots with a Mathematical Image Analysis Algorithm." 2009 Student Research Conference (22nd Annual Undergraduate and 7th Annual Graduate Research Conference, April 7, 2009), Kirksville, MO.
• Ma Z, *Forrester B, *Ren Yu-yu, and Hammond T (2009) A Computer-Assisted Mathematical Image Analysis Method for Quantifying Gravitropic Curvature in Plant Roots. Submitted to the Bulletin of Mathematical Biology. 2009.

About Prof. John Ma:
Dr. Ma was born and raised in Nanjing, China. He completed his undergraduate study in Plant Nutrition and Soil Chemistry in Nanjing Agricultural University, then moved to the U.S. and obtained his M.S. from the University of Hawaii at Manoa, and his Ph.D from the Penn State University in Plant Biology. He joined Truman biology faculty in 2005. His research interests include gravitational biology, plant stress physiology and adaptation to the environment, plant mineral nutrition, root biology, and biological modeling.

Dr. Ma enjoys music, movies, and anything related to art. He also likes to read books on history when he has time.

About Prof. Todd Hammond:
Todd was born in Berkeley, California, and proceeded to do both his undergraduate and his graduate work in mathematics at the University of California there, where both his parents and one grandmother graduated before him. During this time he also did software development at Lawrence Berkeley National Laboratory, both at the Real Time Systems Group there and also in contract work for the Department of Energy. Although he made a conscious decision to focus on mathematics rather than computer science, his work with computers has colored his interests in mathematics as well. In particular, a primary research interest of his is in computability theory, an area, which among other things studies mathematical algorithms. In recent years, he has become especially interested in the more applied aspects of mathematical algorithms. Other interests include the history of mathematics (and of computer science), ethnomathematics, and mathematics education. He met his wife during a four year post-doctoral position at the University of Chicago (partially funded by the National Science Foundation), and happily became a midwesterner. He joined Truman in 1994.

Project Description (long):
The ability of plants to establish an upright architecture is dependent on the sensing of and response to gravity, and is critical to their growth, development, and productivity. In roots of higher plants, gravity sensing occurs in specialized sensory cells in the center of the root cap (Juniper et al., 1966; Volkmann and Sievers 1979; Sack 1991; Blancaflor et al., 1998; Ma and Hasenstein 2006). Root gravity sensing and signaling is thought to be regulated by interactions among various cellular structures, such as statoliths, ER, vacuoles, and actin cytoskeleton (Sack, 1997; Zheng and Staehelin, 2001).

To better understand the cellular components and the interactions involved in gravity sensing, it is important to determine the gravitropic sensitivity and response under a variety of physiological and/or environmental conditions. For this purpose, accurate measurement of root curvature is necessary. In this project, we will continue to improve the algorithm we developed from last summer for quantification of root angle change from time-lapse images. It is anticipated that the root curvature algorithms will use techniques developed in the study of Bézier curves such as those of Prautzsch et al., 2002. We also expect to benefit from the experience gained by a STEP project by Theo Elkow in summer 2005 (unpublished). In the interest of the widest possible dissemination of the ideas and methods of this project, it is the intention that any software written in the course of this project will be made publicly available under open source license(s) such as the GPL (Gnu Public License) and/or LGPL (Library Gnu Public License). The successful completion of the project should provide an important analytical tool for use in future experiments in determining the cellular components of the gravisensing structure, and in efforts in quantification of complex biological growth patterns.

• Blancaflor E B, Fasano J M, Gilroy S (1998) Mapping the functional roles of cap cells in the response of Arabidopsis primary roots to gravity. Plant Physiol. 116: 213-222.
• Juniper B E, Groves S, Landau-Schacher B (1966) Root cap and the perception of gravity. Nature 209: 93-94.
• Ma Z, Hasenstein KH (2006) The onset of gravisensitivity in the embryonic root of flax. Plant Physiology 140: 159 – 166.
• Prautzsch H, Boehm W, Paluszny M (2002) Bézier and B-Spline Techniques. Springer-Verlag, Berlin. ISBN 3-540-43761-4.
• Sack F D (1991) Plant gravity sensing. Int Rev Cytol 127: 193-252.
• Sack F D (1997) Plastids and gravitropic sensing. Planta 203, S63-S68.
• Volkmann D, Sievers A (1979) Graviperception in multicellular organs. In Encyclopedia of Plant Physiology, Vol. 7 (W. Haupt and M. Feinleib, eds), pp. 573-600. Springer-Verlag, Berlin. ISBN 3-540-08776-1.
• Zheng HQ, Staehelin LA (2001) Nodal endoplasmic reticulum, a specialized form of endoplasmic reticulum found in gravity-sensing root tip columella cells. Plant Physiol. 125: 252-265.