Growth and Salt Tolerance of Tobacco Hairy Roots with Constitutive Expression of the TaNAC69 Gene

Bread wheat ( Triticum aestivum L.) is one of the most important cereals and staple food crops worldwide and is grown quite often in arid regions of the world where water shortages and salinity cause serious crop losses. The TaNAC69 gene of bread wheat encodes one of the most important transcription factors involved in the regulation of resistance to water deficit caused by drought and hypothermia, but the role of this gene under salinity is poorly understood. This study aimed to clone the TaNAC69 gene of bread wheat in a binary vector with the 35S CaMV promoter and to create hairy roots (HRs) of Nicotiana tabacum L. with constitutive expression of the TaNAC69 gene to assess the effectiveness of the target genetically engineered construct under salinity. As the result of Agrobacterium-mediated transformation of tobacco leaf discs using Agrobacterium rhizogenes, 15 lines of HR cultures were created, in six of which the presence and high level of expression of the target gene were proven. Tobacco HRs with constitutive expression of the TaNAC69 gene were characterized by faster growth rates, greater branching, and higher fresh and dry weights when exposed to 150 mM NaCl than control tobacco HRs without the target gene. Analysis of the antioxidant system revealed increased activity of the enzymes guaiacol peroxidase and glutathione-S-transferase, higher content of proline and water-soluble sugars, and higher total antioxidant capacity in HR with the TaNAC69 gene compared to the untransformed control. The TaNAC69 with the 35S CaMV promoter construct can be recommended for the genetic transformation of crops to increase their resistance to abiotic stresses.