Nitrogen stress-induced TaDof1 expression in diverse wheat genotypes and its relation with nitrogen use efficiency

Nitrogen (N) uptake and nitrogen utilization are two major components of nitrogen use efficiency (NUE), where N-utilization is a function of N-assimilation and N-remobilization. Transcription factor Dof1 regulates Carbon (C) metabolism in the TCA cycle and also controls the NUE in the plant by ensuring optimum C-skeleton supply for N-assimilation. In this study, four diverse wheat genotypes were selected based on their varied response to N stress in a field experiment conducted during 2012–2013. These genotypes are subjected to N-stress in Pots in the next two consecutive years (2014, 2015), where N stress level on year 2 (2015) was higher than year 1 (2014). Expression of Tadof1 was studied in leaf tissue from two growth stages, 30 (stage 1) and 60 (stage 2), days after sowing. TaDof1 expression was found upregulated during year 1 and gradually down-regulated at stage 2 of year 2 when the N-stress was maximum. HS-277, an Efficient NUtE genotype, shows relatively highest TaDof1 expression under limited N-stress; however, the downregulation was also maximum under severe stress. In optimum N supply, GS2 (Glutamine synthetase) and NADH-GOGAT (Glutamate synthase) activity increased in wheat leaves when the plants grew up from stage 1 to stage 2. However, the activity reduced significantly under severe N-stress in the low NUtE genotypes, Sujata and VL-401. Our result shows that role of TaDof1 varies among the wheat genotypes, and this variation is probably one of the factors affecting N-assimilation and ultimately yield as well as NUE.