Inhibition of gibberellin-induced elongation growth of rice by feruloyl oligosaccharides.

The biological activity of cell wall-derived feruloyl oligosaccharides was investigated using a modified micro-drop bioassay. A feruloyl arabinoxylan trisaccharide (FAXX) and a feruloyl arabinoxylan tetrasaccharide (FAXXX) were found to inhibit the gibberellin-induced elongation of dwarf rice (Oryza sativa L., cv, Tan-ginbozu) that had been treated with uniconazole (S-3307), an inhibitor of the biosynthesis of gibberellins. An arabinoxylan trisaccharide (AXX) was ineffective. The growth-inhibitory effect of feruloyl oligosaccharides depended on their feruloyl and glycosyl moieties. The amount of esterified diferulic acid residues in the cell walls of the second leaf sheath of rice seedlings that had been treated with FAXX was almost same as that of controls. Feruloyl oligosaccharides did not inhibit the incorporation of [14C]leucine into acid-precipitable proteins by suspension-cultured maize cells, whereas cinnamic acid and its derivatives strongly inhibited such incorporation.