PLASTID DEVELOPMENT IN IOJAP‐ AND CHLOROPLAST MUTATOR‐AFFECTED MAIZE PLANTS

Plastids affected by either iojap or chloroplast mutator fail to green, and altered plastids are maternally transmitted to subsequent generations. The ultrastructure of iojap ‐affected plastids indicates that these plastids contain no ribosomes and are capable of supporting little internal membrane organization in either light or dark‐grown plants. Chloroplast mutator ‐affected plastids of light‐grown plants contain some organized internal membrane structures. In dark‐grown plants, chloroplast mutator ‐aftected plastids contain a crystalline prolamellar body, numerous vesicles, and osmiophilic granules. The chloroplast mutator ‐affecled etioplasts display an abnormal distribution of lamellar membranes; these membranes, rather than radiating in a spokelike pattern from the prolamellar body, are condensed into a portion of the organelle. Light causes disruption of the prolamellar body in chloroplast mutator ‐affected plastids without promoting the organization of a normal thylakoid membrane system. The effects of iojap and chloroplast mutator are cell autonomous and apparently influence the individual plastid, as evidenced by the persistence of heteroplastidic cells containing normal and affected plastids.