Identification of a nuclear transcription factor-Y (NF-Y) gene family in pepper and analysis of a CaNF-YC1-CaTIFY7-CaCBF1a/b transcription factor module under cold stress

Pepper is a popular crop, and its preference for a warm environment means that the frequent occurrence of extreme cold weather worldwide has increased the urgency to breed cold-tolerant vegetable varieties. The exploration of cold-tolerant genes has become a key research focus. However, research on transcription factors that regulate low-temperature tolerance in pepper plants remains limited. In this study, whole-genome analysis of the nuclear transcription factor Y (NF-Y) family was performed, revealing cold stress induction and transcription activation activity of CaNF-YC1. Silencing CaNF-YC1 increased the H₂O₂ content and decreased the activities of the POD, SOD, and CAT enzymes under cold stress, significantly reducing the plants' low-temperature tolerance. Conversely, overexpression of CaNF-YC1 enhanced pepper plants’ tolerance to low-temperature stress. RT-qPCR, yeast one-hybrid, and analysis of GUS/LUC reporter genes in tobacco demonstrated that the CaNF-YC1 transcription factor activates expression of CaCBF1a and CaCBF1b by binding to their promoters. Yeast and tobacco assays revealed that the CaNF-YC1-CaTIFY7 complex finely regulates activation of the CaCBF1a and CaCBF1b promoters. The results indicate a crucial role for the CaNF-YC1-CaTIFY7-CaCBF1a/b molecular module in regulating core factors of low-temperature signaling in peppers.