INDUCTION OF BROWNING OF MALE FLOWERS OF CRYPTOMERIA-JAPONICA BY TREATMENT WITH FATTY-ACIDS - MECHANISM AND THE ROLE OF TRANS-2-HEXENAL

The effect of treatment with fatty acids on the browning of male flowe rs of Cryptomeria japonica and its mechanism were studied with emphasi s on the role of trans-2-hexenal, The effect of treatment with fatty a cids on the browning of male flowers was the highest when fatty acids were applied at the end of August, decreasing month by month thereafte r in parallel with the seasonal changes in lipoxygenase activity. tran s-2-Hexenal, which is formed from linolenic acid in a reaction catalyz ed by lipoxygenase (EC 1.13.1.13), stimulated the evolution of ethylen e and acetaldehyde in male flowers predominantly, with resultant enhan cement of the activity of phenylalanine ammonia-lyase (EC 4.3.1.5), an d the browning of male flowers. A possible biochemical pathway for bro wning of male flowers of Cryptomeria japonica is discussed.