NAC056 transcription factor confers freezing tolerance by positively regulating the expression of CBFs and NIA1 in Arabidopsis

Abstract

It is well known that freezing stress can seriously affect the growth and development of plants. However, the mechanisms of these effects and plant response to freezing stress need to be further explored. Here, we identified a NAC family transcription factor (TF) NAC056 that can promote freezing tolerance. The NAC056 mRNA level was obviously induced by freezing stress in roots. We showed that the nac056 mutant compromised freezing tolerance. NAC056 acts positively in response to freezing by directly promoting the key CBF pathway genes. Interestingly, we found that the CBF1 regulates nitrate assimilation by regulating the nitrate reductase gene, NIA1, in plants, therefore, NAC056-CBF1-NIA1 form a regulatory module for the assimilation of nitrate and the growth of roots under freezing stress. In addition, 35S::NAC056 transgenic plants promoted freezing tolerance. The cbfs triple mutant could partly reverse the 35S::NAC056-induced freezing tolerance. Thus, NAC056 confers freezing tolerance through the CBF pathway. Therefore, NAC056 mediates the response of plants to balance plant growth and freezing stress tolerance.