Unusual Ultrastructural Features of the Chloroplast-Chromoplast Transformation in Solanum luteum Fruit

Abstract

The ultrastructure and pigment composition have been followed in the plastids of the ripening fruits of yellow- and orange-fruited cultivars of S. luteum. Chloroplasts of green fruit transform into globular chromoplasts containing large plastoglobules, phytoferritin deposits, and lamellae. Ripe yellow fruit retain some chlorophyll, and have carotenoids typical of photosynthetic tissue. Ripe orange fruit contain ¿-carotene and lutein and their 5,6-epoxy derivatives, and also cis-lutein, neoxanthin, and a trace of neochrome. The ultrastructure of some of the transforming chloroplasts of this fruit is similar to that of plastids from the xan-a*63 barley mutant in that they containextensive lamellar tubules. The unusual ultrastructure of the plastoglobules and the formation of 'thylakoid centres' are discussed.