Loss of the R2R3 MYB, AtMyb73, causes hyper-induction of the SOS1 and SOS3 genes in response to high salinity in Arabidopsis

Environmental stressors, including high salt, drought, and low or high temperatures, are often associated with significant losses in agricultural productivity. Plants have evolved a diverse array of signaling pathways to modulate their development in response to various environmental challenges. Here, we report the characterization of a member of the R2R3-MYB transcription factor family, AtMyb73. The expression of AtMyb73 was up-regulated by salt stress but not by other stresses. The maximum level of AtMyb73 expression occurred at 6 h of 300 mM NaCl treatment. Under salt stress, atmyb73 ko mutant plants exhibited higher survival rates compare to wild type (Col-0) plants. Using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis, we determined that the accumulation of salt overly sensitive (SOS) transcripts, SOS1 and SOS3, was higher in atmyb73 ko and atmyb73 eko plants than in wild type plants in response to 300 mM NaCl treatment. These results indicate that AtMyb73 is a negative regulator of SOS induction in response to salt stress in Arabidopsis thaliana.