Overexpression of transcription factor SlNAC35 enhances the chilling tolerance of transgenic tomato

The NAC (NAM, ATAF1/2, and CUC2) transcription factor family participates in responses to various kinds of environmental stimuli in plants. However, the roles of NAC protein in cold resistance, especially in the cold resistance of tomatoes, are not completely understood. This study examined the roles of a tomato (Solanum lycopersicum) NAC transcription factor (SlNAC35) in resisting chilling using transgenic tomatoes. GUS staining and expression analysis revealed that SlNAC35 expression was induced at 4 °C, thereby suggesting its involvement in plant responses to chilling stress. Moreover, transgenic lines over-expressing SlNAC35 exhibited high chlorophyll content, fresh mass, and low accumulation of reactive oxygen species and membrane damage under chilling stress. These results indicated that SlNAC35 overexpression enhanced the chilling tolerance of transgenic tomatoes. High expressions of cold tolerance markers SlCOR518 and SlCOR413IM1 were observed under chilling stress in transgenic lines. This observation suggested that SlNAC35 overexpression enhanced the chilling tolerance of transgenic lines by involving the c-repeat binding factor-cold stress response (CBF-COR) signaling pathway and by regulating SlCOR expression.