Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 1998
Publication Date: N/A
Interpretive Summary: Flavonoids are important secondary metabolites. They have been reported as having a wide variety of physiological effects in both animals and plants, serving as enzyme activators and inhibitors, metal chelators, antioxidants, free radical scavengers, transcription regulators, phytohormones and also are mutagenic, anti-mutagenic, carcinogenic, anti-carcinogenic, cytotoxic, anti-neoplastic, anti-inflammatory, and anti-allergenic substances. This study clearly shows that flavonoid chemical composition may be regulated by the chromosome composition of the tree. This study will aid in future breeding programs aimed at improving fruit flavonoid composition.
Technical Abstract: Diploid Citrus paradisi Macf. (grapefruit) cultivars (cvs.) were found to consistently contain higher levels of Brix %, acidity (i.e., citric acid/ml), and Brix/acid ratios in the juice than their tetraploid counterparts. In contrast, higher levels of narirutin, naringin, and neohesperidin were found in the fruit juices of tetraploid cvs. In naringin-dominate grapefruit leaf types such as "Hall" and "Seedy Marsh," naringin levels were higher in tetraploid leaves than in diploid leaves. "Hall" leaves had less narirutin but more neohesperidin in tetraploid leaves than in diploid leaves. However, in "Seedy Marsh" leaves the opposite occurred. Neohesperidin-dominate leaf type, "Imperial," and "Royal" cvs. have higher neohesperidin levels in tetraploid leaves than in diploid leaves while exhibiting less narirutin levels in tetraploid leaves than in diploid leaves. Triploid progeny expressed variable levels of flavonoids, some are several fold over that found in their diploid and tetraploid parents.