Figure 2.

Contribution of MGDG to the accumulation of Pchlide and carotenoids in etiolated seedlings. A, Pchlide content in 4-d-old etiolated seedlings of amiR-MGD1 grown under −DEX and +DEX conditions. Total and nonphotoactive Pchlide were extracted before and after flash treatment, respectively. Data are means ± se from 12 (L4w) or 15 (L4g) independent experiments. The amount of photoactive Pchlide was estimated by subtracting the amount of nonphotoactive Pchlide from total Pchlide. B, Pchlide content in 4-d-old etiolated L4w seedlings treated with DEX at different times after seeding. L4w plants were treated with DEX from the beginning of seeding (+DEX), 1 d after seeding (1-d DEX), or 2 d after seeding (2-d DEX). Seedlings grown in the absence of DEX were analyzed as the untreated control (−DEX). Data are means ± se from seven to 12 independent experiments. Different letters indicate significant differences (P < 0.05, Tukey-Kramer multiple comparison test). C, Pchlide accumulation in etiolated amiR-MGD1 L4w seedlings grown for 2 to 5 d under −DEX and +DEX conditions. Data are means ± se from six to 12 independent experiments. D, Immunoblot analysis of total LPOR proteins (∼37 kD) in 4-d-old etiolated seedlings of amiR-MGD1 L4w. As a loading control, Ponceau-stained proteins between ∼25 and ∼50 kD blotted onto a membrane are shown. Representative data from three biologically independent experiments are shown. E, Total carotenoid content in 4-d-old etiolated seedlings of amiR-MGD1 L4w. Data are means ± se from eight independent experiments. In A, C, and E, asterisks indicate significant differences from the −DEX control (**, P < 0.01; and ***, P < 0.001, Student’s t test).