Abstract
A highly methyl esterified linear α-(1→4)-linked polygalacturonide, isolated from a water extract of seeds of Ficus awkeotsang Makino, was used for the study of elicitor-active oligosaccharides on host-parasite interactions in higher plants. Oligogalacturonides (OLGAs), obtained from awkeotsang polygalacturonide or low methyl esterified apple pectin by treatment with the purified endo-pectate lyase (EC 4.2.2.2) of Ermnia carotovora, were found to induce glyceollin accumulation in soybean cotyledons. The de-esterified awkeotsang-OLGAs was precisely fractionated by anion-exchange chromatography using a QAE-Sephadex A-25 column, and was assayed for the elicitor activity. Among the purified Oligogalacturonides with DP 3 to 12, it was found that 4, 5-unsaturated hexa-a-1, 4-galacturonide of the low molecular elicitor-active Oligogalacturonides (DP 5 to 7) also was a potent elicitor as well as the 4, 5-unsaturated deca-a-l, 4-galacturonide of the high molecular elicitor-active Oligogalacturonides (DP 9 to 11) previously reported by Davis et al.1)
