| Research Abstract |
The mechanism of the induction of phenolic amide compounds (PAC) in potato tissues by β- 1,3-glucooligosaccharide was investigated.
a) Laminarin is a β-1,3-glucooligosaccharide of seaweed origin, which has PAC-inducing activity. The structure of laminarin was analyzed using ^<13>C-NMR, ESI-mass, and chemical methylation techniques.
b) The PAC-inducing activity of other commercially available β-1, 3-glucans was examined. Zymosan, a water insoluble fraction of yeast cell wall, which has been shown to activate the mammalian immune system, also had a PAC inducing activity in potato. Laminariheptaose, a liner β-1, 3-glucoheptasaccharide, had the weak elicitor activity, and the importance of the β-1, 3-linkage in the saccharide structure for the activity was suggested.
c) A liner β-1, 3-glucooligosaccharide without β-1,6-branch was prepared in order to evaluate the effect of β-1, 6-branch in the saccharide on the PAC inducing activity. Hydrolysis of curdran (liner β-1, 3-glucopolysaccharide) successfully afforded the liner β-1,3- glucooligosaccharide with suitable DP.Its elicitor activity was examined in detail.
d)Absolute structure of N-p-Coumaroyloctopamine, which represents the most part of PAC in potato, was determined to be S.
e) Activity of four PAC-biosynthesis-related enzymes, PAL, 4CL, THT and TyrDC, was transiently up-regulated in a concerted manner by the β-1,3-glucan elicitor treatment.
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