Transcription factor CaNAC1 regulates low-temperature-induced phospholipid degradation in green bell pepper

摘要

Phospholipids constitute the main component of biomembranes. During low-temperature storage and transportation of harvested bell peppers (Capsicum annuum), chilling injury participates in their decay. A primary cause of this chilling injury is phospholipid degradation. In this study, three genes encoding phospholipase D (PLD) were identified from bell peppers and their activities were examined under cold stress. Low temperature (4 degrees C) induced strong accumulation of the CaPLD alpha 4 transcript, suggesting that it is associated with the phenomenon of phospholipid degradation and destruction of cell membranes. Low temperature also significantly induced increased amounts of NAM-ATAF1/2-CUC2 (NAC) domain transcription factors. CaNAC1 was found to interact with the promoter of CaPLD4 in a yeast one-hybrid screen. Electrophoretic mobility shift and ss-glucuronidase reporter assays demonstrated that CaNAC1 binds to the CTGCAG motif in the CaPLD alpha 4 promoter, thereby activating its transcription and controlling phospholipid degradation. The ubiquitination sites of the CaNAC1 protein were characterized by liquid chromatography-tandem mass spectrometry. We conclude that CaNAC1 is a transcriptional activator of CaPLD alpha 4 and suggested that it participates in the degradation of membrane lipids in bell peppers when they are stored at low temperature.