Salinity, freezing and osmotic stresses are major limiting factors for plant life and agriculture. Naturally-adapted plants are able to grow in environments that eliminate all crops and most other plant species; hence, these are potential models for determining critical mechanisms of tolerance. Thellungiella halophila (salt cress) is an extremophile that can complete its life cycle in seawater concentrations of NaCl and is capable of tolerating freezing temperature extremes. Salt cress provides the ideal salt/osmotic and freezing tolerant genetic model system because it is closely related to the Arabidopsis thaliana and has other attributes of a genetic model, e.g. small plant size, high seed yield, short life cycle and a small genome. Simple and efficient transformation through floral dipping has been achieved. Salt and freezing tolerance genes will be identified from salt cress through loss-of-function genetic analyses by generating and screening T-DNA insertion lines. Mutants will then be screened from the insertion lines and the corresponding tolerance genes cloned via a TAIL PCR, or a plasmid rescue approach. The broader impact of the project includes functional demonstration of how a halophyte and cryophyte genetic model system that is a relative of Arabidopsis can be exploited as a genetic resource to cope with the yield-reducing effects of osmotic, ionic and freezing stresses. The molecular genetic resources will be made available to the entire plant biology community through the ABRC at Ohio State University. There will be continued emphasis on undergraduate student training through "hands on" participation in research.
