Abstract
The ultrastructural reversion of chromoplasts to chloroplasts in regreening Valencia oranges is described. During reversion of chromoplasts to chloroplasts the grana-fretwork system is evidently built up from small vesicles which pinch off from the inner plastid membrane. As the chromoplast regreens, the large osmiophilic globules become reduced in size and number, and there may be a utilization of the lipid material of these globules during the formation of the internal membrane system. It is suggested that irreversible senescences of the chromoplasts probably is dependent on changes in the plastid membrane.
