Disruption of a CAROTENOID CLEAVAGE DIOXYGENASE 4 gene converts flower colour from white to yellow in Brassica species

Abstract

SummaryIn Brassica napus, yellow petals had a much higher content of carotenoids than white petals present in a small number of lines, with violaxanthin identified as the major carotenoid compound in yellow petals of rapeseed lines.Using positional cloning we identified a carotenoid cleavage dioxygenase 4 gene, BnaC3.CCD4, responsible for the formation of flower colour, with preferential expression in petals of white-flowered B. napus lines. Insertion of a CACTA-like transposable element 1 (TE1) into the coding region of BnaC3.CCD4 had disrupted its expression in yellow-flowered rapeseed lines.a-Ionone was identified as the major volatile apocarotenoid released from white petals but not from yellow petals. We speculate that BnaC3.CCD4 may use d-and/or a-carotene as substrates.Four variations, including two CACTA-like TEs (alleles M1 and M4) and two insertion/deletions (INDELs, alleles M2 and M3), were identified in yellow-flowered Brassica oleracea lines. The two CACTA-like TEs were also identified in the coding region of BcaC3.CCD4 in Brassica carinata. However, the two INDELs were not detected in B. napus and B. carinata. We demonstrate that the insertions of TEs in BolC3.CCD4 predated the formation of the two allotetraploids.

Carotenoids from fruits and vegetables: Chemistry, analysis, occurrence, bioavailability and biological activities

“…Plastid-localized carotenoid cleavage dioxygenase (CCDs) possibly play A C C E P T E D M A N U S C R I P T (Bruno, Beyer, & Al-Babili, 2015). In Brassica species, disruption of a CCD 4 gene converts flower colour from white to yellow (Zhang et al, 2015). Various classes of CCDs are identified in plant, which catalyze the important steps in biosynthesis of apocarotenoid, carlactone, strigolactones, abscisic acid and many other flavor and aroma compounds.…”

Synthesis and reactivity of a 4His enzyme model complex

“…3 illustrates selected molecular orbitals: HOMO, HOMO-1, LUMO, and LUMO+1 for 1 . It is found that the highest occupied molecular orbital (HOMO, β-412) is largely distributed over the d xz /d yz orbital while the HOMO−1 (α-416) is associated with the d x 2 -y 2 and nitrogen sp 2 orbital in an antibonding fashion. The lowest unoccupied molecular orbital (LUMO, β-413) is primarily distributed over ring unhybridized p orbitals and to a lesser extent the d xz /d yz orbital while the LUMO+1 (β-414) consists of unhybridized p orbitals.…”

“…Scaling and absorption corrections were applied using SADABS 29 multi-scan technique, supplied by George Sheldrick. The structures are solved by the direct method using the SHELXS-97 program and refined by least squares method on F 2 , SHELXL-2014 30 , which are incorporated in OLEX2. 31 All non-hydrogen atoms were refined anisotropically.…”

“…1 In plants, carotenoids carry out a variety of critical functions. They operate as accessory light-harvesting components (antenna complex) 2, 3 of photosynthetic systems, light induced antioxidants (brought about by the low-lying triplet state poised to quench triplet chlorophyll and singlet oxygen 4 ), membrane fluidity regulators, pigments (yellow to red-orange; important in attracting pollinators) 2 for leaves, vegetables, and fruits. 5 Along with carotenoids being essential in plants, carotenoid-derived products serve as important sources of bioactive compounds called apocarotenoids.…”

“…6 In animals, carotenoids yield essential precursors necessary for vision, embryonic development, cellular homeostasis, and immunity (Vitamin A). 2, 8, 9 Carotenoid Cleavage Dioxygenases (CCDs) are enzymes possessing a nonheme site and are found in all life forms. CCD processes carotenoids and related substrates.…”