抄録
The contents of wall-bound hydroxycinnamic acids and their dimers were compared between elongated and non-elongated cells of suspension-cultured Mentha. Wall-bound peroxidase activity was also investigated. The main hydroxycinnamic acids esterified to these two kinds of cell walls were ferulic and caffeic acids. Eleven dehydrodicaffeic acid isomers and six dehydrodiferulic acid isomers formed through C-C and C-O-C coupling processes, were detected by GC-MS from the extracts released from the walls of non-elongated cells. On the other hand, only four dehydrodicaffeic acid isomers and three dehydrodiferulic acid isomers were found in the walls of elongated cells. Amounts of monomers of ferulic and caffeic acids and their 5,5′-dehydrodimers in non-elongated cell walls were about ten and twenty times higher, respectively, than those in the elongated cell walls. There was a close correlation between the amount of 5,5′-dehydrodimers and activity of wall-bound peroxidase in non-elongated and elongated cells. The level of 5,5′-dehydrodimers accumulated at a higher rate than monomers in non-elongated cell walls. These results suggest that the dimerization of ester-linked ferulic and caffeic acids by peroxidase and the increase in amounts of their 5,5′-dehydrodimers are important factors in the cessation of cell elongation in Mentha suspension culture.
