Transcription factor PtNAC101 negatively regulates the lignin synthesis and salt tolerance in Populus trichocarpa

NACs are one of the largest transcription factor families in plants and play an important role in coping with abiotic stress. A novel NAC domain containing transcription factor, PtNAC101, was isolated from Populus trichocarpa. Specific expression analysis found that PtNAC101 was expressed at the highest level in the xylem, and was induced by salt stress. PtNAC101 localized to the nucleus and had the transcriptional activation activity. Functional studies found that PtNAC101 overexpression weakened the tolerance of Populus trichocarpa to salt stress, and significantly reduced the activities of enzymes related to antioxidant such as POD, SOD and CAT in vivo. In addition, the lignin content in the PtNAC101 overexpression lines was lower than that of WT under salt stress, and the genes related to lignin synthesis were down-regulated by PtNAC101. Taken together, these results suggest that PtNAC101 was a repressor of lignin biosynthesis and may play a negative regulatory role in the salt stress response.