Induction of BAP1 by a Moderate Decrease in Temperature Is Mediated by ICE1 in Arabidopsis

Temperature variations at the nonextreme range modulate various processes of plant growth, development, and physiology, but how plants perceive and transduce these temperature signals is not well understood. Moderate cooling from 28 degrees C to 22 degrees C induces transcription of a number of genes in salicylic acid-dependent and -independent manners. Here, we report the study of the transcriptional control of the BON1-ASSOCIATED PROTEIN1 (BAP1) gene that is responsive to a moderate decrease of temperature as well as to many environmental stimuli. Using reporter genes under the control of series of regions of the BAP1 promoter, we identified a 35-bp fragment that is necessary and sufficient for the BAP1 transcript induction by a moderate cooling. This fragment also confers an induction of BAP1 by cold and reactive oxygen species-generating paraquat. Furthermore, the INDUCER OF CBF EXPRESSION1 (ICE1) protein that is involved in transcriptional control of cold responses is found to bind to a MYC element in this promoter and is required for the cooling induction of BAP1. The ice1 mutant has a low induction of BAP1 and enhanced resistance to a bacterial pathogen. Thus, responses to a moderate decrease in temperature may utilize components in the cold response as well as a potentiating signaling involving salicylic acid.