Why Sequence Thellungiella halophila?

The build-up of salt in agricultural soils is a widespread problem that limits the growth and yield of important crop species worldwide. With few exceptions, crop plants are glycophytes, unable to adapt to the ionic, osmotic, and oxidative stresses induced by elevated levels of salt in the soil. Halophytes are plants that are capable of maintaining growth in extremely saline environments. Sequencing of Thellungiella halophila, a halophytic relative of both the genetic model Arabidopsis thaliana (Arabidopsis) and agriculturally important members of the genus Brassica (e.g., Oilseed Rape) will be critical for understanding the molecular mechanisms underlying halophyte success during growth in salt and discovery of the associated determinants. Achieving these goals will be an essential part of strategies to engineer and breed more salt-tolerant crop plants.

The genome sequence of T. halophila will be a critical resource for the fields of stress biology, evolutionary biology, and comparative genomics. A number of T. halophila genes induced by exposure to salt have no known function or low sequence similarity with those previously described for its glycophytic relative, Arabidopsis. In addition, more than half the genes induced by salt have been shown to be regulated differently between T. halophila and Arabidopsis. These results indicate that T. halophila has evolved a high degree of salt tolerance independently of Arabidopsis and that it will be an invaluable source of salt tolerance determinants for transfer to crop plants. Because T. halophila is also cold tolerant, its importance as a model for abiotic (non-biological) stress will extend beyond salinity. Based on its relationship to Arabidopsis and the Brassica, sequence information for T. halophila also will inform studies of genetic variation within the Brassicaceae and add to existing annotation projects in Arabidopsis. Sequencing the T. halophila genome is therefore aligned with the Department of Energy’s mission to support scientific innovation that will advance the national, economic, and energy security of the United States.

Principal Investigators: Karen S. Schumaker and Rod A. Wing (Univ. of Arizona) and Thomas Mitchell-Olds (Duke Univ.).