Saponin-like substances inhibit alpha-galactosidase production in the endosperm of fenugreek seeds. A possible regulatory role in endosperm galactomannan degradation

• Published in: Planta 1993-02, Vol.189 (2), p.207-212
• Main Authors: Zambou, K, Spyropoulos, C.G, Chinou, I, Kontos, F
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; alpha-galactosidase; Biological and medical sciences; biosynthesis; Dehydration; Endosperm; enzyme activity; Enzymes; Ethanol; Fenugreek; Fundamental and applied biological sciences. Psychology; Germination and dormancy; Imbibition; inhibition; Leaching; Plant physiology and development; Saponins; Spermatozoa; Testa; Trigonella foenum-graecum
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/BF00195078

When fenugreek (Trigonella foenum-graecum L.) endosperms plus testa ("endosperms"), which had been isolated from 5-h-imbibed seeds, were incubated for at least 2 h under germination conditions, they leaked substances which, like exogenous abscisic acid (ABA), inhibited the production of fenugreek endosperm alpha-galactosidase. However, unlike ABA, 8 h treatment with these inhibitors had no effect on fenugreek "endosperms" which had been isolated from 15-h-imbibed seeds and leached for 2 h. This indicated that either their inhibitory action was on processes which were related to the production of alpha-galactosidase and had been completed by this time, or that there might be factors present which inactivate these inhibitors. It was also concluded that the action of the "endosperm" leachate could not be attributed to the presence of ABA. The activity of the leachate decreased when it originated from "endosperms" imbibed for periods longer than 25 h and thin-layer chromatography (TLC) of extracts from these "endosperms" showed decreased contents of the leachable inhibitors as imbibition proceeded. From the seed leachate, which had a TLC pattern and inhibitory action similar to that of the "endosperm", were isolated three substances which, when applied to "endosperms", inhibited the production of alpha-galactosidase activity. According to their chromatographic behaviour and their reaction with specific reagents, there are strong indications that these substances are saponins. These diffusible saponin-like substances were located in both endosperm and perisperm and their physiological role is discussed.