Figure 3.

Growth Performances of pgrl1 and Wild-Type C. reinhardtii Lines Cultivated Photoautotrophically in Liquid or Solid Media.

(A) and (B) Growth performances were analyzed in liquid cultures using 1-liter photobioreactors operated as turbidostats. Cell density was measured using an absorption probe and maintained at a constant level (≈1.5 × 10⁶ cells mL⁻¹) by injection of fresh medium. Growth rates were measured in LL (120 μmol photons m⁻² s⁻¹) or HL (500 μmol photons m⁻² s⁻¹) in cells grown in the presence of 2% CO₂-enriched air (A) or air (B). Wild-type progenitor line (dark bars); pgrl1 mutant (white bars). Shown are means ± sd (n = 7 in [A] or n = 3 in [B]).

(C) and (D) Growth on solid medium was assessed by plating serial (1/10) dilutions of an algal culture (initial culture concentration 10⁶ cells mL⁻¹) on a minimal medium under constant LL (50 μmol photons m⁻² s⁻¹) or HL (200 μmol photons m⁻² s⁻¹) in the presence of air enriched with 2% CO₂ (C) or air (D). Shown are representative cultures out of three biological repeats showing similar effects.

(E) to (H) Growth performances of pgrl1 and the wild type in response to LL to HL switch. The culture was maintained at a low cell density (≈4 × 10⁵ cells mL⁻¹) by injection of fresh medium during a 48-h period at 50 μmol photons m⁻² s⁻¹. When indicated by arrows, light intensity was increased to 800 μmol photons m⁻² s⁻¹. The injection of fresh medium was stopped and the OD₈₈₀ increase recorded. Wild-type line ([E] and [F]); pgrl1 ([G] and [H]). Transients shown are representative of three independent experiments.

(I) and (J) Growth performances of pgrl1 and wild-type lines under fluctuating light. Low cell density (≈4 × 10⁵ cells mL⁻¹) cultures were performed at 50 μmol photons m⁻² s⁻¹ (LL) or under a 50/800 μmol photons m⁻² s⁻¹ (5 min/1 min) fluctuating light regime (LL+1’LP). Wild-type progenitor line (dark bars) and pgrl1 (white bars). Shown are means ± sd (n = 2).