Fig. 7. GRAM RNA expression in a periclinal chimera. In situ hybridisation with either a full-length GRAM cDNA probe (A,C,E) or a transcribed region of GRAM downstream from the transposon insertion in gram-3 (3' probe; B,D,F). Both probes detect wild-type GRAM transcripts (A,B). Transcripts from gram-3 are detected, at a reduced level, by the full-length probe (C) but not the 3' probe (D). In the phenotypically wild-type shoot of a periclinal chimera, the full-length probe detects GRAM transcripts in all cell layers of developing leaves (E) whereas the 3' probe detects a high level of transcripts only in the epidermal cell layer (F), indicating that the shoot carries a GRAM⁺ revertant allele in the epidermal, L1 cell layer. Each row shows adjacent sections from the same shoot apex and the sections in each column were probed together on the same microscope slide.