Figure 5.

CCH mRNA was up-regulated during leaf senescence. The fifth and sixth leaves of Arabidopsis plants (ecotype Ler) were removed at 16, 23, or 28 DAG, and total RNA was extracted and used for RNA-blot analysis (leaf photographs are representative of leaves at each time point). RNA blots were created with equal amounts of each RNA sample, as determined by spectrophotometry and ethidium bromide staining. Equal loading was confirmed by detection of 18S rRNA with a radiolabeled probe. RNA blots were probed with [³²P]ATP-labeled cDNA probes for 18S rRNA (control for equal loading on the RNA blot), CCH cDNA, chlorophyll a/b-binding protein (CAB), and the senescence-associated gene (SAG 12).