Variability of nitrogen uptake and assimilation among N-efficient and N-inefficient wheat (Triticum aestivumL.) genotypes

Abstract

Ten genotypes of wheat (Triticum aestivum L.) were grown for 20 days in complete nutrient solution with 1 mM (nitrogen-insufficient), 4 mM (nitrogen-moderate) and 10 mM (nitrogen-sufficient) nitrogen (N) levels, and nitrogen efficiency (NE) was analyzed. Of these 10 genotypes, VL829 was identified as the most N-efficient, while HUW234 the most N-inefficient. To find out the physiological basis of this difference, we investigated the possible role of NO 2À 3 influx across the root cell plasma membrane in conferring NE by measuring the short-term NO 2À 3 uptake in selected 10 genotypes. Uptake experiments revealed the presence of two separate nitrate transporter systems mediating high-and low-affinity nitrate uptake. Interestingly, the nitrate uptake by the roots of VL829 is mediated by both high-and low-affinity nitrate transporter systems, while that of HUW234 by only low affinity nitrate transporter system. The study suggests that root NO 2À 3 uptake rate may play an important role in conferring N-efficiency of wheat genotypes under N-limiting condition. Also the activities and expression levels of nitrate assimilatory enzymes in N-efficient and N-inefficient wheat genotypes showed that nitrate reductase (NR) and glutamine synthetase (GS) play important roles in N assimilation under low-nitrogen conditions.

Biochemical and physiological characterization for nitrogen use efficiency in aromatic rice genotypes

“…Hakeem et al (2012) reported that high NUE genotypes showed more NR activity and consistent even with increase in N levels where as NR activity was increased with increase in N levels in low NUE genotypes. High NUE genotypes have low threshold level for NR activity and hence there was no change in NR activity with increase in N levels (Anjana et al, 2007;Chandna et al, 2012).…”

Phosphorus Deficiency in Plants: Responses, Adaptive Mechanisms, and Signaling

“…Plants allocate new biomass to the organs used for acquiring the scarce resources to adjust the ionic imbalance (Marschner 1995 ). Many studies have focused on the relationships between nutrition, plant growth, and development and have explained the mechanisms of ion transport and the biochemical pathways infl uenced by mineral scarcity (Hermans et al 2006 ;Chandna et al 2012 ;Hakeem et al 2012a , b ). Although understanding about the molecular and physiological processes involved in sensing, signaling, and allocation of defi cient nutrients is poor, but with onset of microarray technologies to study gene expression, study of transcriptional changes associated with mineral imbalance has become easier (Hammond et al 2004 ).…”

The Effects of N Input Level on N Uptake, N Remobilization and Agronomic Traits Under Deficit Irrigation Condition in Winter Wheat

“…The biochemical parameters associated with internal N assimilation affect the N physiological efficiency in plants and N storage in grains (Chandna et al, 2012;Zhang et al, 2015). The activities of NR, NIR, and GS, the critical enzymes involving internal N assimilation efficiency, regulate the NUE behaviors of plants (Oaks, 1994;Truax et al, 1994;Esen et al, 2015).…”