Chromoplasts and leucoplasts are members of a dynamic group of plant cell organelles called plastids. Plastids have distinct and specialized metabolisms and structures. Yet these organelles originate from the same precursor structure, proplastids, and are interconvertible depending on the environment and requirements of the plant cell. It is interesting that plastids are theorized to have been free-living procaryotic organisms that became involved in a symbiotic relationship with primitive plants millions of years ago.
Plastids have their own circular DNA that replicates and is similar to present day procaryotes.
Chloroplasts are the most familiar plastids. These contain the green photosynthetic pigments, chlorophyll, used by plants to harvest energy from the sun. Amyloplasts are storage organelles. Starch that is stored on a permanent basis, more than a few hours, is found in these plastids. Chromoplasts are found in many flower petals and fruits.