Fig 7. Transcript levels of genes encoding either urea cycle enzymes or enzymes in linked pathways determined at 400 ppm and 100 ppm CO₂ and standardized to PP2A.

Data are the mean of five biological replicates ± SD. Significance was tested according to the two-tailed Student's t-test (* p<0.05). Values were expressed as log₂ ratios to allow this test. ARGAH, arginine amidohydrolase; ASL, argininosuccinate lyase; ASSY, argininosuccinate synthetase; CARA, carbamoyl phosphate synthetase A;CARB, carbamoylphosphate synthetase B; NAGS2, N-acetyl-L-glutamate synthase 2; δOAT, ornithine-δ-aminotransferase; OTC, ornithine transcarbamylase; P5CS1, pyrroline-5-carboxylate synthetase; PRODH, proline dehydrogenase.