Sensitivity of the chloroplast division cycle to chloramphenicol and cycloheximide in cultured spinach leaves

Abstract

In cultured spinach leaf tissue a single cycle of chloroplast division (i.e. a doubling of chloroplast numbers), and its associated chloroplast DNA (cp DNA) synthesis is insensitive to chloramphenicol (CAP), but inhibited by cycloheximide (CHI). The chloroplast doubling takes approx. 24 h. CAP is taken up by the tissue and acts on the chloroplast as it inhibits greening after a 24 h incubation, and has no effect on cell size. Both inhibitors clearly inhibit chloroplast division and cp DNA synthesis after 48 h, possibly as a consequence of a general effect on chloroplast development. It is postulated that both chloroplast division and cp DNA synthesis are initiated in response to cytoplasmic factors with the chloroplast constriction mechanism residing in the chloroplast itself.