RCD1-DREB2A interaction in leaf senescence and stress responses in Arabidopsis thaliana.

Transcriptional regulation of gene expression is one major determinant of developmental control and stress adaptation in virtually all living organisms. In recent years numerous transcription factors controlling various aspects of plant life have been identified. The activity of transcription factors needs to be regulated to prevent unspecific, prolonged or inappropriate responses. The transcription factor DREB2A (DEHYDRATION-RESPONSIVE ELEMENT BINDING 2A) has been identified as one of the main regulators of drought and heat responses, and it is regulated through protein stability. In the present paper we describe evidence that the interaction with RCD1 (RADICAL-INDUCED CELL DEATH 1) contributes to the control of DREB2A under a range of conditions. The interaction is mediated by a novel protein motif in DREB2A and a splice variant of DREB2A which lacks the interaction domain accumulates during heat stress and senescence. In addition RCD1 is rapidly degraded during heat stress, thus our results suggest that removal of RCD1 protein or the loss of the interaction domain in DREB2A appears to be required for proper DREB2A function under stress conditions.