Fig. 3.

Reduced NtLCYB expression causes decreases in plant growth, pigment content, and gene expression in tobacco plants. (A) Side and top view from 4-week-old RNAi and wild type plants. Scale bar: 10 cm. (B) NtLCYB expression levels measured by qPCR. (C–G) Pigment content (carotenoids and chlorophylls) measured by UPLC. (H–L) Gene expression analysis of carotenoid and carotenoid-related pathways measured by qPCR. The expression of Actin as a stable reference gene was used for normalization. A general decrease in transcript abundance of all three lines for the majority of the genes involved in carotenoid, MEP, chlorophyll, and GA pathways was observed. Decrease in transcript accumulation of genes encoding LHC subunits and enzymes involved in tetrapyrrole biosynthesis was observed. Columns and bars represent the means and SEM for the qPCR (three biological replicates and three technical replicates) and UPLC (five biological replicates). Unpaired two-tailed Student’s t-test was performed to compare transgenic lines with the wild type. Letters represent statistical differences among the lines. *P<0.05, **P<0.001, ***P<0.0001. ABA, abscisic acid; Car, carotenoids; Chl, chlorophyll; GA, gibberellins; LHCs, light harvesting complex; MEP, 2-C-methyl-D-erythritol 4-phosphate; WT, wild type; Xan, xanthophylls.