Analysis of the expression of MtGS1a , MtGS1b and MtGS2a during a diurnal cycle. Leaf samples were collected 30 minutes before or after the transition day/night and night/day and every 4 hours over a period of 24 hours. A. The graphic represents the quantification of MtGS1a, MtGS1b and MtGS2a transcripts by qRT-PCR, normalized to the housekeeping gene MtElf1-α, and the determination of total GS activity in the leaves. B. Western blot analysis using the Anti-Glnγ antibody. Equal amount of protein (30 μg) was loaded on the gel. Results are representative of two independent experiments, each using three biological replicates.