Generation of chimeric repressors that confer salt tolerance in Arabidopsis and rice

We show here that transgenic Arabidopsis plants that expressed chimeric repressors derived from the AtMYB102, ANAC047, HRS1, ZAT6 and AtERF5 transcription factors were tolerant to treatment with 400 mM NaCl, which was lethal to wild-type plants. The transgenic plants grew well, without any apparent differences from the wild-type plants under normal growth condition. The transgenic lines expressing the AtMYB102, ANAC047 and HRS1 chimeric repressors germinated in the presence of 225 mM NaCl, while those expressing the ZAT6 and AtERF5 did not. However, the latter lines were tolerant to osmotic stress and germinated in the presence of 600 mM mannitol, suggesting a link between responses to salt and osmotic stress. Expression of the AtMYB102, ANAC047, ZAT6 and AtERF5 genes was induced by salt treatment, while that of HRS1 was repressed. HRS1 has transcriptional repressive activity and appears to suppress the expression of factors that negatively regulate salt tolerance. Microarray analysis revealed that the levels of expression of DREB1A, DREB2B and several genes for ZAT transcription factors rose 10-to 100-fold in the AtMYB102 chimeric repressor line under both normal and stress conditions. Elevated expression of DREB- and ZAT-related genes might be involved in the salt tolerance of the AtMYB102 chimeric repressor line. Transgenic rice plants expressing chimeric repressors derived from Os02g0325600 and Os03g0327800, rice homologues of HRS1 and ANAC047, were tolerant to salinity stress demonstrated by suppression of growth inhibition and ion leakages. Expression of a chimeric repressor provides an effective strategy for enhancing tolerance of plants to abiotic stress.