Abstract
Plastids are cell organelles that have essential biosynthetic and metabolic activities. To understand the basic mechanism of plastid differentiation from chloroplast to chromoplast, we prepared and analyzed proteins from various types of plastid in"Micro-Tom"tomato fruits at four developmental stages (Mature Green, Yellow, Orange, Red) using shotgun proteomics. The plastids were isolated from tomato fruits by Nycodenz density gradient centrifugation. We identified approximately 440 plastid proteins using a LC-MS/MS. The plastid proteins with the greatest numbers are detected at the orange stage. It is thought that plastids at the orange stage are in possession of both chloroplast and chromoplast functions, and have active proteins related to metabolic production including photosynthetic proteins and carotenoids.
When we compared the chromoplast proteome data in "Micro-Tom"with the data in a bell pepper, we found 42 common proteins.
We observed that approximately 50% of the chromoplast proteins are involved in the metabolic process according to GO. We suggest that chromoplast is involved in production and accumulation of various metabolites.
