Find in Library

To elucidate the function of the cold-resistance regulatory gene <i>FmNAC1</i> from <i>Fraxinus mandshurica</i> Rupr., this study identified the role that overexpression of the <i>FmNAC1</i> gene plays in tobacco growth and cold-stress regulation. The cloned <i>FmNAC1</i> gene from <i>F. mandshurica</i> is 891 bp in length and encodes 296 amino acids. Our subcellular localization analysis confirmed that <i>FmNAC1</i> is primarily located in the nucleus and functions as a transcription factor. <i>FmNAC1</i> is responsive to cold and NaCl stress, as well as to the induction of IAA, GA, and ABA hormone signals. To further elucidate its function in cold resistance, four transgenic tobacco lines expressing <i>FmNAC1</i> (<i>FmNAC1-OE</i>) were generated through tissue culture after the Agrobacterium-mediated transformation of wild-type (WT) <i>Nicotiana tabacum</i> L. These <i>FmNAC1-OE</i> plants exhibited accelerated growth after transplantation. When exposed to low-temperature conditions at −5 °C for 24 h, the rates of wilting and yellowing of the <i>FmNAC1-OE</i> plants were significantly lower than those of the WT tobacco plants. Additionally, the membrane integrity, osmotic regulation, and reactive oxygen species (ROS)-scavenging abilities of the <i>FmNAC1-OE</i> tobacco lines were better than those of the WT plants, indicating the potential of the <i>FmNAC1</i> gene to improve plant cold resistance. The gene expression results further revealed that the <i>FmNAC1</i> transcription factor exhibits regulatory interactions with growth-related genes such as <i>IAA</i> and <i>AUX1</i>; cold-resistance-related genes such as <i>ICE</i>, <i>DREB</i>, and <i>CBF1</i>; and genes involved in the clearance of reactive oxygen species (ROS), such as <i>CAT</i> and <i>SOD</i>. All of this evidence shows that the <i>FmNAC1</i> transcription factor from <i>F. mandshurica</i> plays a key role in contributing to the enhancement of growth, cold resistance, and ROS clearance in transgenic tobacco plants.