Figure 5.

mRNA expression in chloroplasts and polysome association of chloroplast mRNA. A, Northern-blot analysis of transcripts in wild-type (WT) and hcf243 plants. Transcripts of psbA, psbB, psbC, and psbD genes were detected by probing the filter with the appropriate gene-specific probes. B, Polysome association in wild-type and hcf243 plants of mRNAs encoding the chloroplast proteins (psbA, psbB, psbC, and psbD). Total extracts were prepared and separated on Suc gradients. Ten fractions of equal volume were collected from the top to the bottom of the Suc gradients, and northern-blot analysis was performed on equal proportions of the RNA purified from each fraction. rRNAs were detected by ethidium bromide staining.