The time-course of accumulation of two membrane proteins during fruit ripening was examined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis and western blots in tissue extracts of Capsicum annuum L., vars Emerald Giant, Albino, and DNAP VS-12. The proteins, named ChrA and ChrB, were previously shown to occur specifically in chromoplasts. Fruit development was divided into five stages based on changes in color.
MATERIALS AND METHODS
Plant MaterialFruits of Capsicum annuum L., vars Emerald Giant, Albino, and DNAP VS-12 were grown in the greenhouse. Fruits were harvested and the proteins extracted on the same day. In analyzing the molecular genetics of chromoplast development, it is useful to consider chr2 and we have undertaken a program for the isolation of members ofthe set. For reasons cited earlier (2), we have chosen to work with the bell pepper Capsicum annuum L.From the available data it appears unlikely that chr genes will be found in the plasmid genome (2,3,7,8,11,12). Plant breeders, however, have identified a number of genes that are probably chr. C. annuum has four Mendelian loci that affect chromoplast development in mature fruit (5) and two other loci that affect chromoplast development in immature fruits (10). Our strategy has been to isolate chromoplast-specific proteins and, through these, to isolate chr genes.We previously reported the specific accumulation of a 58-kD and a 35-kD protein in chromoplasts of C. annuum (4).