Carotenoids and epoxide cycles in mature-green tomatoes.

The concentration of total xanthophylls in maturing tomato fruit (Lycopersicon esculentum Mill. cv. Moneymaker) passed through a minimum during the period comprising the mature-green and breaker stages. This period marked a rapid decrease in chlorophyll and preceded the accumulation of lycopene and its colorless precursors, phytoene and phytofluene. An epoxide cycle was found to operate in the mature-green fruit, as evidenced by the increase in concentration of zeaxanthin at the expense of violaxanthin upon illumination of the fruit with visible light, whereas in the dark, the reverse process occurred. A second epoxide cycle of lesser amplitude was observed between lutein and lutein monoepoxide.