Fig. 4.

rRNA processing is affected in clpr2-1 seedlings. To determine whether the clpr2-1 mutant showed any defects in 70 S chloroplast rRNA processing and ribosome assembly, rRNA populations from stages 1.07 or 1.08 and stage 1.14 clpr2-1 and wt plants were determined. A, sucrose density centrifugation and RNA analysis by ethidium bromide staining. The two cytosolic 18 and 25 S rRNAs are clearly visible in 40 and 60 S particles and assembled 80 S particles. Two additional, high molecular mass bands (between the 18 and 25 S bands) are visible in the clpr2-1 seedlings and represent unprocessed rRNA species. B, Northern blot analysis of total RNA extracted from wt and clpr2-1 seedling leaves. RNA was blotted to membrane and stained by methylene blue or analyzed with specific probes against chloroplast ribosomal RNA molecules derived from genes rrn23, rrn4.5, rrn16, and rrn5 as indicated above each panel. RNA species accumulating in clpr2-1 are indicated by asterisks and arrows.