Fig. 3. Dark-induced senescence in detached wild-type and mutant leaves. (A) Chlorophyll levels in detached leaves following an 8 day incubation in the dark. Black bars represent chlorophyll levels just after detachment and white bars represent chlorophyll levels of leaves incubated in the dark for 8 days. Error bars indicate s.d. (n=6). (B) Time course of chlorophyll loss in Columbia and arf2-8 plants. Black circles indicate chlorophyll levels of Columbia leaves and white circles indicate arf2-8 leaves. (C) Northern blot analysis of gene expression in detached leaves. Leaves from Columbia and arf2-8 plants were detached, placed in darkness for various time periods, and then used for chlorophyll measurement or RNA extraction. Error bars indicate s.d. (n=6).