Table 2.

Transcriptional changes on the cellular hallmarks of N starvation

Trend	Pathway	Representative examples	Timestamp
Up	Pentose phosphate pathway	Glucose-6-phosphate dehydrogenase	18 min
	Purine catabolism	Xanthine dehydrogenase Adenosine deaminase	18–30 min
	Urea metabolism	Carbamoyl phosphate synthetase Ornithine transcarbamylase Agmatine deiminase Allophanate hydrolase Urea carboxylase	24–30 min
	Glutamine metabolism	Glutamine synthetase	30 min
	Polyamines oxidation	Copper amine oxidase	18 min–2 h
	TAG biosynthesis	Diacylglycerol acyltransferase	24–45 min
Down	FA β-oxidation	Acyl-CoA oxidases 2,4 dienoyl-CoA reductase	24 min
	Purine and pyrimidine biosynthesis	Adenylosuccinate synthase Uridine 5′-monophosphate synthase	24 min
	FA biosynthesis	3-ketoacyl-CoA-synthase Biotin synthase Acetyl-CoA carboxylase, 3-ketoacyl-ACP reductase	24–45 min
	Translation	Translation initiation factors Translation elongation factors Release factors	24 min–4 h
	Amino acid biosynthesis	Threonine deaminase Shikimate dehydrogenase Dihydrodipicolinate synthase 3-Phosphoglycerate dehydrogenase	24–30 min
	Protein folding	Chaperonins	45 min
	Calvin cycle	Triose phosphate isomerase Transketolase Ribose-5-phosphate isomerase	45 min
	Carbon concentrating mechanism	Malate dehydrogenase	45 min
	Polyamines biosynthesis	Ornithine decarboxylase Adenosylmethionine decarboxylase Spermidine synthase	45 min–4 h
	Glycerolipid metabolism	Phosphatidate cytidylyltransferase Glycerol-3-phosphate acyltransferase	45 min–4 h
	Chlorophyll biosynthesis	Chlorophyll synthase Geranylgeranyl diphosphate synthase Geranylgeranyl reductase Uroporphyrinogen decarboxylase	60 min–4 h
	Two-component peroxide-detoxifying system	NADPH-dependent thioredoxin reductase 2-Cys peroxiredoxin Peroxidase	2 h
	Photosynthesis	Ferredoxin Photosystem I and II proteins ATP synthase Cytochrome b6f complex subunits PsbP	2–8 h
	Glutathione-ascorbate cycle	Ascorbate peroxidase Prohibitin, thioredoxin	4 h
	Glycolysis	Glyceraldehyde-3-phosphate Dehydrogenase	4 h

Summary of key cellular pathways differentially regulated with representative transcript examples. Timestamp and direction of regulation (trend) are indicated