Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Xylomic And Genomic Approaches To Understanding Root To Shoot Signaling And Root Growth Maintenance In Maize Under Drought

Daniel P. Schachtman¹ , Jason Q.D. Goodger¹ , Hans J. Bohnert² , Georgia Davis³ , Yajun Wu⁴ , Robert E. Sharp³ , Gordon K. Springer³ , Henry T. Nguyen³

¹  Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO 63132

²  Department of Plant Biology, and Department of Crop Sciences, U. Illinois, Urbana IL 61801

³  Departments of Agronomy and Computer Science, U. Missouri, Columbia, MO 65211

⁴  Department of Plants, Soils and Biometeorology, Utah State University, Logan, Utah

Maize roots send chemical signals to leaves at early stages of drought and these signals lead to slower growth and reduced transpiration. While maize leaves stop growing as drought becomes more severe, roots have a remarkable ability to maintain growth. Both maintenance of root growth and root to shoot signaling are important physiological processes that allow maize to adapt to soil water deficits. Little is known about the molecular mechanisms that determine these physiological processes.
Kinematic studies revealed different responses of cell elongation to water deficit in distinct regions of the growth zone of the maize primary root. Based on these findings, we studied the transcriptome of maize roots under water deficient using ESTs and SAGE analysis. Results from studies on the changes in gene expression that occur in four regions of the root tip: 0-3, 3-7, 7-12, and 12-20 mm will be described.
The comprehensive analysis of xylem sap provides another important approach for investigating relationships between root-derived signals in plants and their effect on transpiration and growth. Xylomics, encompasses the determination of proteins, peptides, hormones, sugars and ions present in extracted xylem sap. The development of xylomics for maize will be described as well as our use of this approach to gain a better understanding of root to shoot signaling in maize plants subjected to water stress. Progress on gene profiling of maize roots using oligo arrays will also be described in relationship to changes in xylem sap composition.
(Funding from NSF Plant Genome DBI-0211842 is gratefully acknowledged).