BrRZFP1 a Brassica rapa C3HC4-type RING zinc finger protein involved in cold, salt and dehydration stress

Abstract

C3HC4-type RING zinc finger proteins are known to be essential in the regulation of plant processes, including responses to abiotic stress. Here, we identify, clone and examine the first C3HC4-type RING zinc finger protein (BrRZFP1) from Brassica rapa under stress conditions. Phylogenetic analysis of BrRZFP1 revealed strong sequence similarity to C3HC4-type zinc finger proteins from Arabidopsis that are induced by abiotic stresses. Diverse environmental stresses, including salt and cold, were found to induce BrRZFP1 transcripts greater than eightfold in B. rapa. Additional strong induction was shown of the stress hormone abscisic acid, together suggesting that BrRZFP1 could play a role as a general stress modulator. Similar profiles of induction for each of these stresses was found in both root and shoot tissues, although at much higher levels in roots. Constitutive expression of BrRZFP1 in Nicotiana tabacum was conducted to further analyse how changes in gene expression levels would affect plant stress responses. BrRZFP1 overexpression conferred increased tolerance to cold, salt and dehydration stresses. This was observed in several assays examining growth status throughout development, including increased germination, fresh weight and length of shoots and roots, as well as enhanced chlorophyll retention. These results suggest that the transcription factor BrRZFP1 is an important determinant of stress response in plants and that changes in its expression level in plants could increase stress tolerance.