Identifying a Carotenoid Cleavage Dioxygenase (CCD4) Gene Controlling Yellow/White Fruit Flesh Color of “Piqiutao” (White Fruit Flesh) and Its Mutant (Yellow Fruit Flesh)

Abstract

To better understand the fruit flesh coloration mechanism of peach (Prunus persica), the composition and accumulation of carotenoids were compared, the expression profile of key genes involved in carotenoid biosynthetic and catabolic pathways was performed, and the differentially expressed genes were identified using "Piqiutao" (white fruit flesh) and its mutant yellow "Piqiutao" at different fruit development stages. The results showed that the total carotenoid content in yellow "Piqiutao" was remarkably higher than that of "Piqiutao," and the accumulation of β-cryptoxanthin, α-carotene, and β-carotene was significantly different, which was most likely caused by the differential expression of CCD4. Therefore, CCD4 may be an essential gene that causes the yellow fruit flesh of yellow "Piqiutao." However, the coding region sequence of CCD4 was entirely identical, and the intron was inserted by a retrotransposon in "Piqiutao" and its mutant, indicating that the expression difference was not caused by the sequence mutation and retrotransposon insertion.

The transcription factor complex CmAP3-CmPI-CmUIF1 modulates carotenoid metabolism by directly regulating the carotenogenic gene CmCCD4a-2 in chrysanthemum

“…Carotenoids are cleaved by carotenoid cleavage dioxygenases (CCDs), and these enzymes are generically divided into five subfamilies: NCED (nine-cis-epoxycarotenoid dioxygenase), CCD1, CCD4, CCD7, and CCD8 [ 47 ]. A large number of studies have reported that the differential expression of CCD1s and CCD4s results in differences in carotenoid content in various plant species and cultivars, such as the different colored fruits of peach ( PpCCD4 [ 8 , 48 ]) and summer squash ( CpCCD4a and CpCCD4b [ 49 ]) and the different colored flowers of chrysanthemum ( CmCCD4a [ 9 ]), osmanthus ( OfCCD4 [ 10 ]), oncidium ( OgCCD1 [ 50 ]), and daffodil ( NpCCD4 [ 51 ]).…”

Down-regulation of NCED leads to the accumulation of carotenoids in the flesh of F1 generation of peach hybrid

“…revealed the differences in the expression patterns of the CCD4 gene between the white-fleshed ‘Piqiutao’ and its yellow-fleshed mutant. The yellow-fleshed peach mutant had a significantly lower expression level of CCD4 than white-fleshed ‘Piqiutao’, resulting in its yellow flesh phenotype ( Wen et al., 2020 ). In this study, the transcriptome analysis of BF1 and HF1 revealed that CCD8 is probably the gene in the CCD family that affects the flesh color of the F 1 hybrid generation.…”

“…For example, CCD4-catalyzed degradation of carotenoids affects the color of fruit flesh and flower. Several studies have demonstrated that inactivation or decreasing the expression of CCD4 could result in the accumulation of carotenoids in peach flesh ( Brandi et al., 2011 ; Adami et al., 2013 ; Falchi et al., 2013 ; Ma et al., 2014 ; Bai et al., 2016 ; Wen et al., 2020 ). NCED has been isolated from a variety of species, and it lower expression level can impede the breakdown of carotenoids, leading to changes in plant color ( Rodrigo et al., 2006 ; Jiang et al., 2019 ; Lana et al., 2020 ; Yungyuen et al., 2021 ).…”

The Genetic Components of a Natural Color Palette: A Comprehensive List of Carotenoid Pathway Mutations in Plants

“…CCD4 in flowering plants is mainly active in chromoplasts, where it determines coloration in petals and fruits by degrading carotenoid pigments. Knockout mutants of CCD4 in ipomea, chrysanthemum, and brassica caused white petals to turn pale-yellow/yellow, and in peach, they caused a change from white to yellow-fleshed fruits ( Adami et al, 2013 ; Ma et al, 2014 ; Zhang et al, 2015 ; Jo et al, 2016 ; Watanabe et al, 2018 ; Wen et al, 2020 ). In Arabidopsis, ccd4 and ccd1 mutants increased seed carotenoid levels, mainly in lutein, neoxanthin, and violaxanthin, with a more pronounced effect in ccd1 mutants ( Gonzalez-Jorge et al, 2013 ).…”