White interrupts the carotene biopath prior to formation of the lycopene precursors but after the gene that produces green when ripe. The interesting thing about white is that the entire carotene biopath - including both lycopene and carotene - is still present and can produce pigments with a simple modification such as grafting onto a rootstock that has the correct gene. This is why a cross of white X green often produces a red fruited F1. This also explains certain published examples of graft translocation triggering changes in fruit phenotype.
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