Figure 4.
Age‐dependent senescence in wild‐type (wt) and GR2 RNAi (igr2‐7, igr2‐9, and igr2‐14) plants (A) Morphologies of leaves. Bars = 5 mm. (B, C, D, and E) Measurements of chlorophyll content, Fv/Fm, malondialdehyde (MDA) content, and membrane ion leakage. (F, G) Expression of the senescence‐related marker genes, SAG12 and SAG13. Transcript levels were determined by real‐time PCR using ACT2 as an internal control. For SAG13, the relative transcript levels detected at day 35 in igr2‐9 plants were assigned a value of 1 after normalization to ACT2 transcript levels. For SAG12, the relative transcript levels detected at day 40 in the igr2‐9 plant were assigned a value of 1 after normalization to ACT2 transcript levels. The fourth rosette leaves from wt and RNAi plants grown in soil were sampled at the indicated days after emergence. The values are means ± SD of three independent experiments.