Accumulation of alpha-Tocopherol in Senescing Organs as Related to Chlorophyll Degradation

alpha-Tocopherol (alpha-T) has been identified, using gas chromatography-mass spectroscopy and (1)H- and (13)C-nuclear magnetic resonance, in senescing leaves of Melia azedarach L. The content of alpha-T increased concomitantly with the breakdown of chlorophyll in senescing Vinca and Melia leaves. An increase in alpha-T was found also in detached Melia leaves, senescing in either light or darkness and in senescing, ethylene-treated orange leaves and fruit. The possibility that phytol, which is released from chlorophyll by chlorophyllase is utilized for the biosynthesis of alpha-T is discussed. Senescing leaves of the low chlorophyllase plants, parsley and tobacco, did not contain alpha-T in measureable amounts.