A novel bud mutation that confers abnormal patterns of lycopene accumulation in sweet orange fruit (Citrus sinensis L. Osbeck)

Abstract

A novel, pleiotropic sweet orange (Citrus sinensis L. Osbeck) mutant, 'Hong Anliu', is described. This mutation causes carotenoid accumulation, high sugar, and low acid in the fruits. Gas chromatographic analysis revealed that high sugar and low acid in the fruit were caused by the accumulation of sucrose and the deficiency of citric acid. The dominant carotenoid accumulated in albedo, segment membranes, and juice sacs is lycopene, which can reach levels that are a 1000-fold higher than those in comparable wild-type fruits. This mutation does not affect the carotenoid composition of leaves. Carotenoid concentration and biosynthetic gene expression of albedo, segment membranes, and juice sacs were dramatically altered by the mutation. Lycopene accumulation in the juice sacs was regulated by co-ordinate expression of carotenoid biosynthetic genes. However, in albedo and segment membranes, the expression of downstream carotenogenic genes seems to be feedback induced by lycopene accumulation. This implies that there must be at least two modes regulating lycopene accumulation in 'Hong Anliu' fruit. Taken together, these results suggest that massive amounts of lycopene might be synthesized in the juice sacs and then transported to the segment membrane and the albedo, which leads to lycopene accumulation there.

A Comprehensive Analysis of Chromoplast Differentiation Reveals Complex Protein Changes Associated with Plastoglobule Biogenesis and Remodeling of Protein Systems in Sweet Orange Flesh

“…RNA was extracted from segment membranes and juice of cv Anliu and cv Hong Anliu fruits as described by Liu et al (2007). RNA quality and quantity measurement, first-strand complementary DNA synthesis, and real-time reverse transcription (RT)-PCR were performed according to Cao et al (2012).…”

Branch girdling at fruit green mature stage affects fruit ascorbic acid contents and expression of genes involved inl-galactose pathway in citrus

“…and actin-R (5?-ATCTGCTG-GAAGGTGCTGAG-3? ), cited from Liu et al (2007), were used as the internal control to normalize the expression level of the target gene among different samples. Two technical replicates of each PCR reaction for every sample of each biological replicate was run on a 96-well plate (Shangyu Yite Plastic Co, China).…”

Presence of Two Variants of Lycopene β-Cyclase Gene in Genomes of Citrus and its Relatives

“…However, like Honganliu sweet orange (17), the lycopene accumulation in the flesh might be caused by the downregulation of LCYb and/or LCYe, or other genes encoding enzymes with lcYb catalyzation ability. Cycb in tomato is a case in point, which encodes a protein showing a similar sequence to capsanthin capsorubin synthase (21), Alquezar et al (3) recently emphasized its lcYb activity in Star Ruby grapefruit.…”

“…According to our previous report, due to lycopene accumulation pink or red-fleshed fruits are found common in citrus, such as cara cara navel orange (26) and honganliu sweet orange (17). Honganliu sweet orange is the pinkfleshed bud mutation of Anliu sweet orange, while Cara cara navel orange is probably originated from Washington navel orange (23).…”

“…Honganliu sweet orange is the pinkfleshed bud mutation of Anliu sweet orange, while Cara cara navel orange is probably originated from Washington navel orange (23). efforts have been made to elucidate the mechanisms underlying lycopene and other specific carotenoid accumulation in citrus fruits to enhance citrus fruit carotenoids production (2,16,17,20,25,26). lycopene accumulation in Star Ruby grapefruit during fruit maturation was associated with a substantial reduction in the expression of both lycopene β-cyclase 2 and β-carotene hydroxylase genes, and the former (15) reported that the carotenoid profiles of fruit of Cara cara navel orange were irrelevant to changes in regulation of LCYb at the transcriptional level.…”