Picea wilsonii NAC Transcription Factor PwNAC30 Negatively Regulates Abiotic Stress Tolerance in Transgenic Arabidopsis

NAC (NAM, ATAF1/2, and CUC2) transcription factors play important roles in the process of abiotic stress response in plants. However, little is known about the functional roles of NACs in Picea (P.) wilsonii. In this study, we functionally characterized a novel P. wilsonii NAC transcription factor PwNAC30 by heterologous expression in Arabidopsis. The results showed that PwNAC30 is mainly localized in the nucleus by transient expression in Nicotiana benthamiana and can function as a nuclear localization transcription factor. β-Glucuronidase (GUS) staining in transgenic Arabidopsis (PwNAC30-promoter-GUS) confirmed the expression pattern of PwNAC30 throughout the plant development process, which is expressed in most of the plant tissues except stamens and petals. Overexpression of PwNAC30 in Arabidopsis significantly repressed the tolerance of seedlings and mature plants to both drought and salt stresses, while exerting no influence on growth and development of plants. The accumulation of reactive oxygen species (ROS) was significantly increased in transgenic plants, and the expression of some stress-responsive genes was obviously inhibited in PwNAC30 overexpression lines. Our study reveals that PwNAC30 functions as a negative regulator of plant tolerance to drought or salt stress, which provides new insights into abiotic tolerance mechanisms in woody plants.