Figure 10.

Model diagram of effects of low NO₃⁻ on Shannong–1(S) and Maotao (M). Depicted on the left is the pathway involved in nitrogen metabolism in S, and depicted on the right is the pathway involved in nitrogen metabolism in M. Under low-concentration KNO₃ treatment, the NRT2.1 protein in S participated in the transport of NO₃^– in a certain way. After NO₃^– enter the cell of S, it promoted the expression of multiple transcription factors such as co-like and NAC, and also inhibited the expression of some transcription factors such as B3, C2H2. Changes in the expression level of these transcription factors increased the expression of multiple genes in the nitrogen metabolism pathway, including PpNRT2.1, PpNR, PpGS, etc. In M, low-concentration KNO₃ treatment did not make the expression of PpNRT2.1 change, so it was uncertain whether NRT2.1 protein is involved in the transport of NO₃^–. After NO₃^– enter the cell of M, it promoted the expression of some transcription factors such as C2H2 and ERF, while inhibited the expression of TCP and Thrihelix transcription factors. Changes in the expression of these transcription factors made the expression of PpNRT5.6, PpNRT5.9, PpGDH2 and other genes change. Arrow: positively, T-bar: negatively, dashed arrow: regulation by some means.