The carotenoid cleavage dioxygenase (CCD) subfamilies
1 and 4 (CCD1, CCD4) target 9,10 and/or 9′,10′
double bonds of C40-carotenoids to form important
volatile C13-apocarotenoids. CCD1 transcript levels correlate
with the emission of b-ionone in petunia flowers
(Simkin et al., 2004).