Pigment Composition and Plastid Structure in Leaves of Carotenoid Mutants of Maize

In monogenic, recessive chloroplast mutants of maize which contain chlorophylls, and lycopene or ζ-carotene but no normal carotenoids, great variability in the size of plastids was associated with a number of ultrastructural abnormalities. In the mutant accumulating lycopene some plastids contain dense bundles of lamellae, whereas the chloroplasts of the ζ-carotene mutant show poor thylakoid development. Neither of the mutants was able to form normal grana. A comparison of chlorophyll/carotenoid ratios in different chloroplast fractions of normal and mutant leaves showed that plastids of small size and delicate structure contain relatively less chlorophyll than fully differentiated chloroplasts.