Variation in Key Flavonoid Biosynthetic Enzymes and Phytochemicals in 'Rio Red' Grapefruit (Citrus paradisi Macf.) during Fruit Development.
In the current study, the phytochemical contents and expression of genes involved in flavonoid biosynthesis in Rio Red grapefruit were studied at different developmental and maturity stages for the first time. Grapefruit were harvested in June, August, November, January, and April and analyzed for the levels of carotenoids, vitamin C, limonoids, flavonoids, and furocoumarins by HPLC. In addition, genes encoding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and 1,2-rhamnosyltransferase (2RT) were isolated, and their expression in grapefruit juice vesicles was studied. Fruit maturity had significant influence on the expression of the genes, with PAL, CHS, and CHI having higher expression in immature fruits (June), whereas 2RT expression was higher in mature fruits (November and January). The levels of flavonoids (except naringin and poncirin), vitamin C, and furocoumarins gradually decreased from June to April. Furthermore, limonin levels sharply decreased in January. Lycopene decreased whereas β-carotene gradually increased with fruit maturity. Naringin did not exactly follow the pattern of 2RT or of PAL, CHS, and CHI expression, indicating that the four genes may have complementary effects on the level of naringin. Nevertheless, of the marketable fruit stages, early-season grapefruits harvested in November contained more beneficial phytochemicals as compared to mid- and late-season fruits harvested in January and April, respectively.
Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University , College Station, Texas 77845, United States.
Priyanka R
PR
Chaudhary
Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University , College Station, Texas 77845, United States.
Haejeen
H
Bang
Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University , College Station, Texas 77845, United States.
Guddadarangavvanahally K
GK
Jayaprakasha
Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University , College Station, Texas 77845, United States.
Bhimanagouda S
BS
Patil
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D001205:Ascorbic Acid / Q000032:analysis; D002338:Carotenoids / Q000032:analysis; D032083:Citrus paradisi / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D044950:Flavanones / Q000032:analysis; D005419:Flavonoids / Q000032:analysis / Q000096:biosynthesis; D005638:Fruit / Q000737:chemistry*; D000067030:Fruit and Vegetable Juices / Q000032:analysis; D011564:Furocoumarins / Q000032:analysis; D018506:Gene Expression Regulation, Plant; D006602:Hexosyltransferases / Q000378:metabolism; D019753:Intramolecular Lyases / Q000235:genetics* / Q000378:metabolism; D036701:Limonins / Q000032:analysis; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics* / Q000378:metabolism; D064209:Phytochemicals / Q000032:analysis / Q000096:biosynthesis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
D044950:Flavanones; D005419:Flavonoids; D011564:Furocoumarins; D036701:Limonins; D064209:Phytochemicals; D010940:Plant Proteins; D002338:Carotenoids; C119641:poncirin; D000217:Acyltransferases; C020141:flavanone synthetase; D006602:Hexosyltransferases; C493952:flavonoid 1-2 rhamnosyltransferase; D010650:Phenylalanine Ammonia-Lyase; D019753:Intramolecular Lyases; C019865:chalcone isomerase; C005274:naringin; D001205:Ascorbic Acid
1; 2-rhamnosyltransferase; Citrus paradisi; chalcone isomerase; chalcone synthase; flavonoids; phenylalanine ammonia-lyase