Submitted to: Plant-Soil Interactions at Low pH
Publication Type: Proceedings
Publication Acceptance Date: 9/30/1996
Publication Date: N/A
Interpretive Summary: Large areas of land within the U.S. and over 40% of the world's arable lands are acidic. In these acid soils, aluminum (Al) toxicity is the primary factor limiting crop production. There is considerable genetic variation in sensitivity to Al between different plant species and genotypes, yet the genetic and molecular basis for Al tolerance is still poorly understood. We need a more complete understanding of the molecular genetics of Al toxicity and tolerance if we are going to be able to develop more Al resistant crop plants. In order to increase our understanding of this topic, we have screened mutagenized populations of Arabidopsis thaliana (a model plant system for molecular and genetic research) and isolated families of Al sensitive and tolerant mutants. We showed that at least 8 different recessive genes conferred Al sensitivity, while we isolated a number of Al tolerant mutants that were controlled by two different dominant genes. We have characterized the nature of these mutant and showed that all of the tolerant mutants excluded toxic Al from the growing root, while some of the sensitive mutants accumulated more toxic Al in the root tip. The significance of these findings are that they provide information about the genetic complexity of Al toxicity and tolerance, and set the stage for future work aimed at cloning the genes associated with Al tolerance. The cloning of these genes should greatly increase our chances of altering or introducing genes into crop plants that confer an increased ability for those plants to grow on acidic, Al toxic soils.
Technical Abstract: Arabidopsis mutants with altered Al sensitivities have been isolated with the goal of identifying genes important for Al resistance and toxicity. By screening in a high-Al environment, 7 Al resistant (alr) mutants were isolated. The alr mutants were semidominant and constitute at least 2 unique loci in Arabidopsis. Nine Al-sensitive mutants (als) were also isolated. Complementation analysis revealed that of the nine als mutants, represent unique loci, indicating that Al sensitivity is genetically complex in Arabidopsis. The characterization of mutants with altered Al sensitivity will provide greater insights into mechanisms of Al toxicity and resistance on a molecular and biochemical level.