Minisymposium 8: Water & Salinity
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M0804: Genetic analysis of drought tolerance
Drought is a common adverse environmental condition that seriously affects crop productivity worldwide. However, deciphering drought tolerance mechanisms has been a challenge to plant biologists. To develop new methods to study drought tolerance mechanisms, we searched for novel phenotypes that are conferred by drought stress. In both model plants and crop plants, we identified a root response, termed drought rhizogenesis, as a developmental adaptation to drought stress. Genetic screens using Arabidopsis were devised and the DIG (for Drought-Induced rhizoGenesis) loci that control drought rhizogenesis were defined. Characterization of the dig mutants revealed that these mutants also exhibit altered drought stress tolerance, indicating that drought rhizogenesis is intimately linked to drought adaptation of the entire plants and can be used as a trait for researchers to access the elusive drought tolerance machinery. Our work thus established a strategy to directly identify drought tolerance determinants. Molecular cloning of several DIG loci revealed that certain chloroplast-targeted proteins are of critical importance to drought tolerance. Furthermore, cell metabolites are found to function as signals in regulating drought stress response and drought tolerance. Our study suggests that that there are multiple mechanisms for drought adaptation, which is consistent with the notion that plant drought tolerance is a complex and multigene trait. Discovery of these novel drought tolerance determinants will be very useful to understand drought tolerance mechanisms and to breed or bioengineer drought resistant crop plants. Supported by USDA-NRI (grant no. 2005-35100-15275 to L.X.).
