Abstract
To dissect mechanisms of tolerance to abiotic stresses, such as salt, drought and low temperature, in monocot plants, we have analyzed rice as a model monocot by molecular genetic approach. We identified three rice salt sensitive (rss) mutants among Tos17-retrotransposon insertional lines. The causative gene for rss1, which exhibits hyper-sensitivity to salt, high osmotic stress, and low temperature, was isolated and revealed to encode a novel protein without any functionally characterized domains. Interestingly, RSS1 homologues are conserved among monocots, primitive angiosperms and gymnosperms, but have not yet been found in dicot plants. Upon salt stress, rss1 displays aberrant root branching and disorganized structures in meristems. Expression of RSS1 was detected preferentially in young tissues, including meristems and primordia of leaves and roots. These results suggest that RSS1 is involved in a novel mechanism for abiotic stress tolerance. Further characterization of RSS1 and identification of RSS2 and RSS3 genes are ongoing.
