This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (22) Citing Articles via Google Scholar Google Scholar Articles by Rebeiz, C. A. Articles by Rebeiz, C. C. Search for Related Content PubMed PubMed Citation Articles by Rebeiz, C. A. Articles by Rebeiz, C. C. Agricola Articles by Rebeiz, C. A. Articles by Rebeiz, C. C.

Articles

Biosynthesis and Accumulation of Microgram Quantities of Chlorophyll by Developing Chloroplasts in Vitro¹

^a Department of Pomology, University of California, Davis, California 95616

Developing chloroplasts were incubated under conditions previously shown to induce protochlorophyll and chlorophyll biosynthesis, as well as chloroplast maintenance and partial differentiation in vitro. In the presence of air, -aminolevulinic acid, coenzyme A, glutathione, potassium phosphate, methyl alcohol, magnesium, nicotinamide adenine dinucleotide, and adenosine triphosphate, microgram quantities of chlorophyll accumulated after 1 hour of incubation. Part of the chlorophyll was not extractable in organic solvents; it is referred to as bound chlorophyll. The amount of bound chlorophyll depended on the degree of cotyledon greening at the time of plastid isolation. Etioplasts with or without a lag phase of chlorophyll biosynthesis synthesized nonphototransformable protochlorophyll and smaller amounts of extractable chlorophyll. As the greening of excised cotyledons progressed, more of the chlorophyll became bound before and after in vitro incubation. It is suggested that this increase in the fraction of bound chlorophyll reflects the biosynthesis of membrane-bound chlorophyll receptor sites. In the absence of cofactors, chlorophyll biosynthesis was blocked and porphyrins accumulated, indicating damage of the chlorophyll biosynthetic chain. It is concluded that chlorophyll accumulation constitutes a potentially convenient tool for the study of thylakoid membrane biogenesis in vitro.

¹ This work was supported in part by Research Grant GB 8546 from the National Science Foundation and by funds from the Illinois Agricultural Experiment Station.