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. Author manuscript; available in PMC: 2022 Oct 6.
Published in final edited form as: Annu Rev Cell Dev Biol. 2021 Aug 5;37:341–367. doi: 10.1146/annurev-cellbio-010521-015047

Figure 1.

Figure 1

Carbon, nitrogen, and phosphorus are essential nutrients that control integrated signaling networks in plants. (a) Sugars are generated by photosynthesis from source leaves and translocated to sink organs. Nitrate (NO −3) and phosphate (PO 3-4) are acquired by roots from the soil and transported to shoots. (b) Glucose-sensor HXK1 and energy sensors TOR and SNRK1 respond to different concentrations of sugars. NRT1.1 is a nitrate transceptor and mediates nitrate-activated CPK-NLP signaling to induced PNRs. Phosphate is taken up by PHT1 and converted to InsP8, which is sensed by SPX to repress PHR1 in PSRs. Other TFs also regulate PNR and PSR. (c) ❶ (Top) HXK1-mediated growth promotion in adult Arabidopsis plants and (bottom) growth arrest in seedlings on high glucose in WT and hxk1 plants. ❷ WT, snrk1, and SNRK1-OX plants. ❸ WT and conditional tor seedlings. ❹ Seedlings supplied with KCl (control) and different nitrogen sources, NH4+, Gln, and NO3−. ❺ Seedlings grown in the medium with (+) or without (−) Phosphate (Pi). Abbreviations: CPK, CALCIUM DEPENDENT PROTEIN KINASE; Glc, glucose; Gln, glutamine; HXK1, HEXOKINASE1; InsP8, inositol phyrophosphate; NLP, NIN-LIKE PROTEIN; OX, overexpression; P, phosphorylation; PHR1, PHOSPHATE STARVATION RESPONSE1; PHT1, PHOSPHATE TRANSPORTER1; PNR, primary nitrate response; PSR, phosphate-starvation response; SNRK1, SNF1-RELATED PROTEIN KINASE1; SPX, SYG1/Pho81/XPR1; T6P, trehalose 6-phosphate; TF, transcription factor; TOR, TARGET OF RAPAMYCIN; WT, wild type.