Chromoplasts are formed either from chloroplast or from leucoplast. For e.g. green tomatoes and chillies turn red on ripening due to the formation of the red pigment called lycopin replacing the cholorophyll. Yellow pigment carotene is developed in the carrot by replacing leucoplast.
Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant. Chloroplasts capture light energy from the sun to produce the free energy stored in ATP and NADPH through a process called photosynthesis.
Chromoplasts (/"KRŌM-ə-plasts"/) are plastids, other than chloroplasts, that produce and store pigments. Found in flowers, leaves, roots and ripe fruits, they contain carotenoids (lipid-soluble pigments ranging from yellow to red in color), which lend color to the plant tissues containing them.
Gerontoplast development is generally seen to be the process of grana being unstacked, loss of thylakoid membranes, and large accumulation of plastoglobuli. Transformation of chloroplasts to gerontoplasts. The term gerontoplast was first introduced in 1977 to define the unique features of the plastid formed during leaf senescence.