Arabidopsis DEAR1, an EAR-motif-containing transcriptional repressor of DREB protein regulate cold responses and pathogen-resistance

Abstract

To examine mechanisms involved in cold stress response, FOX hunting system was used to isolate Arabidopsis gain-of-function mutants. The isolated overexpressor (DEAR1ox), which shows constitutive cell death on rosette-leaves and accelerated leaf senescence, is caused by over-expression of the DEAR1 (DREB and EAR motif protein 1) gene encoding transcriptional repressor that contains a the DREB domain and EAR motif.
Expression of DEAR1 was induced by cold treatment. Transcriptional repression of the cold inducible genes in the DEAR1ox results in reduction of freezing tolerance. Expression of DEAR1 was also enhanced by pathogen infections. The DEAR1ox showed transcriptional promotion of PR genes and highly accumulation of endogenous SA, indicating that the SA-dependent defense pathway is activated in the DEAR1ox, leading to the HR-like cell death phenotype.
These results indicate that the DEAR1 is a key regulator for cross-talk between biotic (pathogen-resistance) and abiotic (freezing tolerance) stress responses.