Ectopic expression of AtICE1 and OsICE1 transcription factor delays stress-induced senescence and improves tolerance to abiotic stresses in tobacco

Inducer of CBF Expression 1 (ICE1) is an upstream regulator of cold-responsive genes in Arabidopsis thaliana and various crop plants. The ice1 mutant is impaired in expression of several transcription factors (TFs) and other genes involved in abiotic stress signaling, suggesting a role beyond cold tolerance. In this study, we examined the abiotic stress responses of transgenic Arabidopsis thaliana constitutively over-expressing AtICE1. These transgenic plants exhibited enhanced tolerance to NaCl and methyl viologen (MV)-induced oxidative stresses. To confirm this enhanced tolerance of ICE1 in a heterologous system, transgenic tobacco over-expressing AtICE1 and OsICE1 were developed. ICE1 over-expressing tobacco transgenic exhibited tolerance to NaCl- and PEG-induced stresses at seedling stage. The tobacco transgenic plants exhibited tolerant phenotype under the situations that mimicked natural drought condition. The improved drought tolerance observed in this study is linked to the maintenance of cell membrane stability and inhibition of stress-induced senescence. Higher expression of homologs of ICE1 target genes such as COR47, HVA22, ERD10, HSF1, EREBP3 and reduced expression of WRKY6, a positive regulator of senescence, indicated that ICE1 expression activated diverse cellular tolerance mechanisms. The study demonstrated that ICE1 is an important positive regulator of cellular tolerance mechanisms associated with multiple abiotic stress response.