Improving Yield and Nitrogen use Efficiency in Wheat by Overexpressing TaNAC2-5A Transcription Factor

TaNAC2-5A is a transcription factor that is part of the NAC family, which is associated with the regulation of plant growth and the response to stress factors, especially in terms of available nitrate. This research is focused on investigating the effect of TaNAC2-5A expression on wheat yield and nitrogen use efficiency of a local wheat variety. A genetic construct for TaNAC2-5A was designed based on a modified wheat transformation vector pSB219, tested in N. tabacum and used for Agrobacterium-mediated transformation of wheat. Transformed wheat plants (T₀) were tested for transgene with PCR until the T₂ generation. Subsequently, the verified plants were evaluated for transgene expression with RT-PCR and qRT-PCR six weeks after germination. The qRT-PCR results revealed that transgenic lines of TaNAC2-5A expressed higher levels of the transcription factor in comparison with the parental line of FSD-2008. The L3 line (NAC2-4 event) indicated 2.25 times higher expression. In agronomic evaluations, the transgenic L3 line was associated with 17.18% higher 1000 grain weight and better root architecture parameters including length, surface area and projected area, suggesting that there is improved nutrient absorption. Also, transgenic lines showed large differences (p ≤ 0.05), in total chlorophyll, protein and sugar contents compared to controls. These findings demonstrate that the constitutive expression of TaNAC2-5A improves wheat yield, root development, and nutrient uptake efficiency, which is beneficial in making high-yield, fertilizer-efficient wheat varieties, thereby having the potential to contribute positively towards food security.