Northern-blot analyses of AtACX3, AtSACX, PED1, and ICL in different Arabidopsis tissues. Each lane was loaded with 10 μg of total RNA isolated from the following Arabidopsis tissues. Lane 1, 6-d-old etiolated cotyledons; lane 2, 6-d-old light-grown green cotyledons; lane 3, rosette leaves; lane 4, senescing rosette leaves; lane 5, cauline leaves; lane 6, stem; lane 7, flowers. Blots were probed with: AtACX3, Arabidopsis ACX3; AtSACX, Arabidopsis SACX (Hayashi et al., 1999); PED1, Arabidopsis thiolase (Hayashi et al., 1998b); ICL, B. napus ICL (accession no. Y13356). The ethidium bromide-stained ribosomal RNA bands are shown as a loading control.