A little membrane protein with 54 amino acids confers salt tolerance in rice (Oryza sativa L.)

The plasma membrane is critical in sensing, interpreting, and transducing environmental signals. In the present study, we characterized an Oryza sativa salt-responsive little protein 1 (OsSRLP1) in rice, which encodes a plasma membrane localized protein containing 54 amino acid residues. Expression of OsSRLP1 was detected in various rice tissues and was significantly induced by low temperature, drought, and salt. Overexpression of OsSRLP1 in rice improved free proline content and modulated ion balance under salt stress, which resulted in enhanced salt tolerance. Compared to wild-type rice, overexpression of OsSRLP1 inhibited seed germination under normal conditions. Interestingly, OsSRLP1 expression was up-regulated in ABL5-Like1 deficiency mutant abl1 compared to wild-type rice under salt treatment. Moreover, it was observed that overexpression of OsSRLP1 led to the dwarfism phenotype, which was correlated to the OsSRLP1 expression level in transgenic rice. In conclusion, OsSRLP1 is a little membrane protein conferring salt tolerance by modulating the ion balance and proline accumulation in rice.