Principle Investigators

Melvin Oliver, Texas Tech

Jeffrey Boore, Lawrence Berkeley National Laboratory
Elizabeth Bray, University of California, Riverside
Thomas Girke, University of California, Riverside
Karen Koster, University of South Dakota
Brent Mishler, University of California, Berkeley
Robert Sharp, University of Missouri Columbia
Steven Tanksley, Cornell University
Jian-Kang Zhu, University of Arizona: Senior-Personnel

Desiccation Tolerance Explained

Power Point Presentation (9MB)
(saving to hard drive first recommended - PC's right click and "save", Mac's< Option> click and save)
  Tortula ruralis:
dried (top); rehydrated (bottom)

Project Summary

The molecular mechanisms that regulate water-deficit tolerance are of major economic importance impacting crop production. Equally important, these mechanisms are fundamental to the processes that enable plants to survive on dry land. Studies comparing molecular responses of a plant species to water deficit with control conditions have netted a catalog of genes that are induced by water deficit. However, we have not gained an understanding of the responses that permit tolerance of, or preserve productivity under, water deficits. Combining a molecular and evolutionary approach, the "Plants Without Water" Genomics Project will address these questions:

  • What are the cellular-level processes of plant adaptation to water deficits in vegetative and reproductive structures?

  • What homologies can be found among the genes that control these processes?

  • What, if any, is the functional and evolutionary relationship between water-deficit responses and desiccation-tolerance?

  • To what extent is seed desiccation-tolerance related to vegetative desiccation-tolerance found in primitive land plants and in some derived seed plants?

  • To the extent that non-tolerant seed plants retain at least some of the array of genes responsible for desiccation-tolerance in their ancestors, how might this enhance the possibility of genetically engineering dehydration-tolerance

"Plants Without Water" will combine phylogenetic, gene expression and function studies to generate a molecular picture of mechanisms that control adaptation to dehydration and the evolutionary link between desiccation tolerance and water-deficit tolerance in modern crops. We will generate, sequence, and annotate deep EST samples from a set of ten plants that differ in tolerance to water deficits, from sensitive to mild stress to tolerant to desiccation (including selective seed ESTs). Phylogenetic comparisons of EST data sets will be used to infer evolutionary relationships and identify potential genes central to the development of stress tolerance in all species or novel to tolerant species. Unigene sets for each species will serve as the basis for microarray expression studies to provide a dynamic picture of each stress response.

Using this information, we will identify a set of target genes that will be functionally dissected using transgenic technology in our model crop, tomato. Since the plant hormone ABA has had a fundamental role in the development of desiccation tolerance, we will transgenically manipulate ABA biosynthesis and signal-transduction pathways to evaluate the role of ABA in the adaptation process. Over-expression and knockout lines will be rigorously tested at the physiological level for water-deficit tolerance in whole plants and seeds. This project will generate large EST and expression pattern data sets across diverse genera for comparative study of dehydration tolerance in crops. Libraries and microarrays will be archived as a public resource. Informatics efforts will be co-ordinated with ongoing plant genome projects providing a large phylogenetic centered database for comparisons between vegetative and developmental gene expression. The EST database will provide annotated links to established genomic and functional information for Arabidopsis, maize, and rice. "Plants Without Water" will generate new hypotheses for the functions of genes involved in water-deficit responses and provide novel strategies for improving water-deficit tolerance in major crops.

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