Engineering drought and salt tolerance in plants using SodERF3, a novel sugarcane ethylene responsive factor

The ability of plants to tolerate salt and drought conditions is crucial for agricultural production worldwide. The increased understanding of the regulatory networks controlling drought stress response has led to practical approaches for engineering salt and drought tolerance in plants. By a single-pass sequencing of randomly selected clones from a λ ZAP-cDNA library generated from ethephon-treated young sugarcane leaves, we identified an expressed sequence tag encoding a putative protein with a DNA-binding domain that is typically found in EREBP/ AP2-type transcription factors. The full-length cDNA clone, named SodERF3 (EMBL accession number AM493723) was further isolated from the excised library. SodERF3 encodes a 240 amino acid DNA-binding protein that acts as a transcriptional regulator of the Ethylene Responsive Factor (ERF) superfamily, but also contains a C-terminal short hydrophobic region resembling an ERF-associated amphiphilic repression-like motif, typical for class II ERFs. This protein binds to the GGC box, and its deduced amino acid sequence contains an N-terminal putative nuclear localization signal. SodERF3 is induced in sugar cane leaves by ethylene, abscisic acid, salt stress and wounding as judged by Northern and Western blots assays. Greenhouse grown transgenic tobacco plants (Nicotiana tabacum L. cv. SR1) expressing SodERF3 were found to display increased tolerance to drought and osmotic stress without any visible phenotypic change in growth and development. According to our results SodERF3 will be a valuable tool to assist the manipulation of plants to improve their stress tolerance.