Transcription Analysis of Genes Encoding the Wheat Root Transporter NRT1 and NRT2 Families During Nitrogen Starvation

In the present study, nitrogen (N) starvation for 8 days significantly inhibited the growth of wheat seedlings as manifested by decreased plant height, shoot fresh weight, and shoot dry weight, although it stimulated root growth. The nitrate and protein contents were markedly reduced and the oxidative stress marker, malondialdehyde content, was markedly increased in the leaves and roots of wheat seedlings during N starvation. The genes encoding the NRT1 and NRT2 families in bread wheat (Triticum aestivum L.) were identified, and their transcription levels were measured using quantitative real-time polymerase chain reaction in the roots of N-starved wheat seedlings. N starvation significantly enhanced the transcription levels of TaNRT1.1 at 2 and 4 days; TaNRT1.3 at 2, 4, and 6 days; TaNRT1.4 at 2 days; TaNRT1.7 and TaNRT1.8 at 2 days; TaNRT2.1 and TaNRT2.2 at 2 days; and TaNRT2.3 at 2 and 4 days. However, the TaNRT1.5 and TaNRT2.4 genes were greatly inhibited at all sampling time points after N starvation, whereas the TaNRT1.2 and TaNRT2.5 genes were dramatically induced. The functions of these transporters in N starvation of wheat seedlings based on these expression profiles are herein discussed.