Pigment and Plastid Ultrastructural Changes in Kumquat ( Fortunella margarita) «Nagami» during Ripening

The oval kumquat (Fortunella margarita) «Nagami» is a citrus relative belonging to the Ru- taceae family. Pigment changes in the whole fruit were investigated at four stages of ripening. During ripening the chlorophylls gradually decreased, disappearing completely in the ripe fruits. The total carotenoid content decreased from 18.7 ¿ig/g to 14.6 /¿g/g and then increased to a level of 38.6 /ig/g in the ripe fruit. The chloroplast carotenoid pattern of the unripe fruit changed gradually into a complex chromoplast pattern in which epoxides predominated, as found in citrus. The major pigment was violaxanthin followed by cryptoxanthin accompanied by its numerous epoxides. The third major pigment was citraurin, a C3o븅apocarotenal so far found only in citrus, especially in flavedo of Citrus reticulata and considered genus specific. Uncommon and characteristic of Fortunella margarita is its capacity to synthesize citraurin both in pulp and peel. The ultrastructural changes involved the chloroplast-chromoplast transformation. Unusual ultrastructural features which may be unique to Fortunella are observed.