, Volume 187, Issue 1, pp 67–74 | Cite as

Control of mannose/galactose ratio during galactomannan formation in developing legume seeds

  • Mary Edwards
  • Catherine Scott
  • Michael J. Gidley
  • J. S. Grant Reid


Galactomannan deposition was investigated in developing endosperms of three leguminous species representative of taxonomic groups which have galactomannans with high, medium and low galactose content. These were fenugreek (Trigonella foenum-graecum L.; mannose/galactose (Man/Gal) = 1.1), guar (Cyamopsis tetragonoloba (L.) Taub.; Man/Gal = 1.6) and Senna occidentalis (L.) Link. (Man/Gal = 3.3), respectively. Endosperms were analysed at different stages of seed development for galactomannan content and the levels, in cell-free extracts, of a mannosyltransferase and a galactosyltransferase which have been shown to catalyse galactomannan biosynthesis in vitro (M. Edwards et al., 1989, Planta 178, 41–51). There was a close correlation in each case between the levels of the biosynthetic mannosyl- and galactosyltransferases and the deposition of galactomannan. The relative in vitro activities of the mannosyl- and galactosyltransferases in fenugreek and guar were similar, and almost constant throughout the period of galactomannan deposition. In Senna the ratio mannosyltransferase/galactosyltransferase was always higher than in the other two species, and it increased substantially throughout the period of galactomannan deposition. In fenugreek and guar the galactomannans present in the endosperms of seeds at different stages of development had the Man/Gal ratios characteristic of the mature seeds. By contrast the galactomannan present in Senna endosperms at the earliest stages of deposition had a Man/Gal ratio of about 2.3. During late deposition this ratio increased rapidly, stabilising at about 3.3, the ratio characteristic of the mature seed. The levels of α-galactosidase in the developing endosperms of fenugreek and guar were low and remained fairly constant throughout the deposition of the galactomannan. In Senna, α-galactosidase activity in the endosperm was low during early galactomannan deposition, but increased subsequently, peaking during late galactomannan deposition. The developmental patterns of the α-galactosidase activity and of the increase in Man/Gal ratio of the Senna galactomannan were closely similar, indicating a cause-and-effect relationship. The endosperm α-galactosidase activity in Senna was capable, in vitro, of removing galactose from guar galactomannan without prior depolymerisation of the molecule. In fenugreek and in guar the genetic control of the Man/Gal ratio in galactomannan is not the result of a post-depositional modification, and must reside in the biosynthetic process. In Senna, the Man/Gal ratio of the primary biosynthetic galactomannan product is controlled by the biosynthetic process. Yet the final Man/Gal ratio of the galactomannan in the mature seed is, to an appreciable extent, the result of galactose removal from the primary biosynthetic product by an α-galactosidase activity which is present in the endosperm during late galactomannan deposition.

Key words

Alpha galactosidase Cell wall storage polysaccharide Cyamopsis Galactomannan (biosynthesis) Senna Trigonella 







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  1. Dawson, R.M.C., Elliott, D.C., Elliott, W.H., Jones, K.M. (1982) Data for biochemical research. Clarendon Press, OxfordGoogle Scholar
  2. Dea, I.C.M., Morrison, A. (1975) Chemistry and interactions of seed galactomannans. Adv. Carbohydr. Chem. Biochem. 31, 241–312PubMedGoogle Scholar
  3. Dea, I.C.M., Morris, E.R., Rees, D.A., Welsh, E.J., Barnes, H.A., Price, J. (1977) Associations of like and unlike polysaccharides: mechanism and specificity in galactomannans, interacting bacterial polysaccharides and related systems. Carbohydr. Res. 57, 249–272Google Scholar
  4. Edwards, M., Dea, I.C.M., Bulpin, P.V., Reid, J.S.G. (1985) Xyloglucan (amyloid) mobilisation in the cotyledons of Tropaeolum majus L. seeds following germination. Planta 163, 133–140Google Scholar
  5. Edwards, M., Bulpin, P.V., Dea, I.C.M., Reid, J.S.G. (1989) Biosynthesis of legume-seed galactomannans in vitro. Cooperative interactions of a guanosine 5′-diphosphate-mannose-linked (1→4)-β-d-mannosyltransferase and a uridine 5′-diphosphate galactose-linked α-d-galactosyltransferase in particulate enzyme preparations from developing endosperms of fenugreek (Trigonella foenum-graecum L.) and guar (Cyamopsis te tragonoloba [L.] Taub.). Planta 178, 41–51Google Scholar
  6. Mallett, I., McCleary, B.V., Matheson, N.K. (1987) Galactoman nan changes in developing Gleditsia triacanthos seeds. Phyto chemistry 26, 1889–1894Google Scholar
  7. McCleary, B.V. (1983) Enzymic interactions in the hydrolysis of galactomannan in germinating guar: the role of exo-β-mannanase. Phytochemistry 22, 649–658Google Scholar
  8. Reid, J.S.G. (1985) Cell wall storage carbohydrates in seeds. Biochemistry of the seed “gums” and “hemicelluloses”. Adv. Bot. Res. 11, 125–155Google Scholar
  9. Reid, J.S.G., Bewley, J.D. (1979) A dual role for the endosperm and its galactomannan reserves in the germinative physiology of fenugreek (Trigonella foenum-graecum L.), an endospermic leguminous seed. Planta 147, 145–150Google Scholar
  10. Reid, J.S.G., Meier, H. (1970a) Chemotaxonomic aspects of the reserve galactomannans in leguminous seeds. Z. Pflanzen physiol. 62, 89–92Google Scholar
  11. Reid, J.S.G., Meier, H. (1970b) Formation of reserve galactoman nan in the seeds of Trigonella foenum-graecum. Phytochemistry 9, 513–520Google Scholar
  12. Reid, J.S.G., Meier, H. (1973) Enzymic activities and galactoman nan mobilisation in germinating seeds of fenugreek (Trigonella foenum-graecum L. Leguminosae). Secretion of α-galactosidase and β-mannosidase by the aleurone layer. Planta 112, 301–308Google Scholar
  13. Saeman, J.F., Buhl, J.L., Harris, E.E. (1945) Quantitative sacchari fication of wood and cellulose. Ind. Eng. Chem. Anal. Ed. 17, 35–37Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Mary Edwards
    • 1
  • Catherine Scott
    • 1
  • Michael J. Gidley
    • 2
  • J. S. Grant Reid
    • 1
  1. 1.Department of Biological and Molecular Sciences, School of Natural SciencesUniversity of StirlingStirlingUK
  2. 2.Colworth HouseUnilever Research LaboratoriesSharnbrookUK

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