CHROMOPLAST ULTRASTRUCTURE AS AFFECTED BY GENES CONTROLLING GRANA RETENTION AND CAROTENOIDS IN FRUITS OF CAPSICUM ANNUUM

Plastids in the fruits of isogenic lines of pepper (Capsicum annuum) were examined by electron microscopy with reference to four genotypes determining the carotenoid composition and the colors red, yellow, brown, and green of the ripe fruit. One gene pair (y⁺/y) influences carotenoid content and the other pair (cl⁺/cl) controls the chlorophyll. The retention of the grana and chlorophyll in the ripe fruits of the brown and green phenotypes is correlated with the cl cl genotype. The y⁺ gene increases the total carotenoids and promotes the formation of red pigments. Giant grana were found in the yellow and green phenotypes, but during ripening these disappeared in the yellow. Unusual dichotomous and concentric grana were observed in the green. Globule-associated carotenoids forming fibrillar crystalloids were present in all color types, although to a lesser degree in the yellow fruit. Membrane-associated carotenoids occurred only in the yellow and green phenotypes.