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 °C) induced strong accumulation of the CaPLDα4 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 CaPLDα4 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 CaPLDα4 and suggested that it participates in the degradation of membrane lipids in bell peppers when they are stored at low temperature.

中文翻译：

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转录因子CaNAC1调节青椒中低温诱导的磷脂降解。

磷脂是生物膜的主要成分。在低温下储存和运输收获的甜椒（辣椒）时，冷害会导致其腐烂。这种冷害的主要原因是磷脂降解。在这项研究中，从甜椒中鉴定了三个编码磷脂酶D（PLD）的基因，并在冷胁迫下检查了它们的活性。低温（4°C）诱导CaPLDα4转录物强烈积累，表明它与磷脂降解和细胞膜破坏现象有关。低温还显着诱导了数量增加的NAM-ATAF1 / 2-CUC2（NAC）域转录因子。发现CaNAC1与CaPLD4的启动子在酵母单杂交筛选中相互作用。电泳迁移率变化和β-葡糖醛酸糖苷酶报道基因分析表明，CaNAC1与CaPLDα4启动子中的CTGCAG基序结合，从而激活其转录并控制磷脂的降解。CaNAC1蛋白的泛素化位点通过液相色谱-串联质谱法进行了表征。我们得出的结论是，CaNAC1是CaPLDα4的转录激活因子，提示当它们在低温下储存时，它参与甜椒中膜脂质的降解。