The Effect of Light and of 2-(4-chlorophenylthio)-triethylamine hydrochloride on Chlorophyll and Carotenoid Contents of Mung Bean Seedlings

Carotenogenesis in mung been seedlings has been shown to beunder phytochrome control. Dark-grown seedlings contain moreindividual carotenoids than light-treated ones, but total carotenoidsare greatly increased by light. As expected, chlorophyll wassynthesized after a lag period on transferring etiolated seedlingsto the light, and there was an increase in total chlorophylland a parallel increase in total carotenoids. CPTA 2-(4-chlorophenylthio)-triethylamine hydrochloride]-treatedseedlings showed a decrease in both total carotenoids and totalchlorophylls. The usual effect of CPTA was also observed withmung bean seedlings, namely that lycopene, normally absent,appeared and increased to 17 per cent of total carotenoids afteran eight-day treatment. A cis-lycopene, possibly poly-cis-lycopene,was observed for the first time in CPTA-treated tissues. Onlyin the presence of CPTA but not on its removal was it possibleto show an inverse relationship between ß-caroteneand lycopene. This suggests that CPTA may not act as a cyclaseinhibitor in green tissues, cyclase being the enzyme/s involvedin the cyclization of carotenes. Phaseolus aureus Roxb., mung bean, carotenes, lycopene, xanthophylls, chlorophyll, 2-(4-chlorophenylthio)-triethylamine hydrochloride