PLANT PHYSIOLOGY , Vol 111, Issue 3 941-946, Copyright © 1996 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Changes in Dehydrodiferulic Acids and Peroxidase Activity against Ferulic Acid Associated with Cell Walls during Growth of Pinus pinaster Hypocotyl
M. Sanchez, M. J. Pena, G. Revilla and I. Zarra
Laboratorio de Fisiologia Vegetal, Facultad de Biologia, Universidad de Santiago, E-15706 Santiago de Compostela, Spain
Hydroxycinnamic acids associated with hypocotyl cell walls of dark-grown
seedlings of Pinus pinaster Aiton were extracted with 1 N NaOH and
identified by gas chromatography-mass spectrometry. The main
hydroxycinnamic acid found was ferulic acid. Diferulic acid dehydrodimers
were also found, with the 8,8-coupled isomer (compound 11) being the
dehydrodiferulate present in the highest amount. However, the 5,5-coupled
isomer, commonly referred to referred to as diferulic acid, was not
detected. Two truxillic acids,
4-4[prime]-dihydroxy-3-3[prime]-dimethoxy-[alpha]-truxillic acids I and II,
were tentatively identified. The 8,8-coupled dehydrodiferulic acid
(compound 11) was the phenolic acid that showed the most conspicuous
changes with hypocotyl age as well as along the hypocotyl axis. Peroxidase
activity against ferulic acid was found in the apoplastic fluid as well as
being ionically and covalently bound to the cell walls. The peroxidase
activity increased with hypocotyl age as well as from the subapical toward
the basal region of the hypocotyls. A key role in the cell-wall stiffening
of 8,8 but not 5,5 dimerization of ferulic acid catalyzed by cell-wall
peroxidases is proposed.
