Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-26T18:30:44.372Z Has data issue: false hasContentIssue false
  • English
  • Français

Phytochrome promotion of mannan-degrading enzyme activities in the micropylar endosperm of Datura ferox seeds requires the presence of the embryo and gibberellin synthesis

Published online by Cambridge University Press:  19 September 2008

R. A. Sánchez  and
L. de Miguel
R. A. Sánchez*
Affiliation:
IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Avda San Martin 4453, 1417 Buenos Aires, Argentina
L. de Miguel
Affiliation:
IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Avda San Martin 4453, 1417 Buenos Aires, Argentina
*
*Correspondence
Get access Rights & Permissions [Opens in a new window]

Abstract

It has been shown that endosperm weakening, a necessary step in the light induction of germination in Datura ferox seeds, is related to the hydrolysis of cell wall mannose polysaccharides. It is demonstrated that the activities of two enzymes involved in mannan degradation (β-mannanase and β-mannosidase) are strongly promoted in the micropylar endosperm, after Pfr formation but long before radicle protrusion. An increase in enzyme activities occurred in dissected seed parts at similar rates to those in whole seeds, but only when at least a portion of the embryonic axis was present during incubation. De-embryonation of seed parts prevented the Pfr-induced increase in hydrolase activities. Exogenous GA3 promoted mannan-degrading enzyme activities both in the micropylar region of far red-treated whole seeds and those of isolated and deembryonated endosperm sections. The response to Pfr and GA3 was far more pronounced in the micropylar portion than in the rest of the endosperm. Pfr promotion of hydrolase activities and germination was blocked by paclobutrazol, an inhibitor of gibberellin synthesis. A close correlation was found between β-mannanase activity measured 45 h after Pfr formation and germination scored 24 h later. These results support the hypothesis that in D. ferox, endosperm softening is promoted by Pfr via the production in the embryonic axis of a factor, probably a gibberellin, which moves to the endosperm where it stimulates cell wall-mannan hydrolytic enzyme activities.

Keywords

PhytochromeDatura feroxendosperm softeninggerminationmannanasemannosidase
Type
Physiology
Information
Seed Science Research , Volume 7 , Issue 1 , March 1997 , pp. 27 - 34
Copyright
Copyright © Cambridge University Press 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bewley, J.D. and Black, M. (1982). The physiology and biochemistry of seeds in relation to germination. Vol. 2., New York, Springer Verlag.CrossRefGoogle Scholar
Bewley, J.D. and Halmer, P. (1980/1981). Embryo-endosperm interactions in the hydrolysis of lettuce seeds reserves. Israel Journal of Botany 29, 118–132.Google Scholar
Dahal, P.J., Nevins, D.J. and Bradford, K.J. (1996). Endosperm cell wall sugar composition and sugars released during tomato seed germination. Plant Physiology 111 (Supplement), 160.Google Scholar
Dutta, S., Bradford, K.J. and Nevins, D.J. (1994). Cell-wall autohydrolysis in isolated endosperms of lettuce (Lactuca sativa). Plant Physiology 104, 345–352.CrossRefGoogle ScholarPubMed
Groot, S.P.C. and Karssen, C.M. (1987). Gibberellins regulate seed germination in tomato by endosperm weakening: a study with gibberellin-deficient mutants. Planta 172, 525–531.CrossRefGoogle Scholar
Groot, S.P.C., Kieliszewska-Rokicka, B., Vermeer, E. and Karssen, C.M. (1988). Gibberellin-induced hydrolysis of endosperm cell walls in gibberellin-deficient tomato seeds prior to radicle protrusion. Planta 174, 500–504.CrossRefGoogle ScholarPubMed
Halmer, P., Bewley, J.D. and Thorpe, T.A. (1975). Enzyme to break down lettuce endosperm cell wall during gibberellin-and light-induced germination. Nature 258, 716–718.CrossRefGoogle Scholar
Hatfield, R.D. and Nevins, D.J. (1986). Characterization of the hydrolytic activity of avocado cellulase. Plant and Cell Physiology 27, 541–552.Google Scholar
Hilhorst, H.W.M. (1995). A critical update on seed dormancy I. Primary dormancy. Seed Science Research 5, 61–74.CrossRefGoogle Scholar
Ikuma, H. and Thimann, K.V. (1963). The role of seed coats in germination of photosensitive lettuce seeds. Plant and Cell Physiology 4, 169–185.Google Scholar
Karssen, C.M. (1994). Hormonal regulation of seed development, dormancy and germination studied by genetic control. pp. 333–350in Kigel, J. and Galili, G. (Eds.) Seed development and germination. New York, Basel, Hong Kong, Marcel Dekker, Inc.Google Scholar
Mella, R.A., Maldonado, S. and Sánchez, R.A. (1995). Phytochrome-induced structural changes and protein degradation prior to radicle protrusion in Datura ferox seeds. Canadian Journal of Botany 73, 1371–1378.CrossRefGoogle Scholar
Nomaguchi, M., Nonogaki, H. and Morohashi, Y. (1995). Development of galactomannan-hydrolysing activity in the micropylar endosperm tip of tomato seed prior to germination. Physiologia Plantarum 94, 105–109.CrossRefGoogle Scholar
Pavlista, A.D. and Haber, A.H. (1970). Embryo expansion without protrusion in lettuce seeds. Plant Physiology 46, 636–637.CrossRefGoogle ScholarPubMed
Psaras, G., Georghiu, K. and Mitrakos, K. (1981). Red-light induced endosperm preparation for radicle protrusion of lettuce embryos. Botanical Gazette 142, 13–18.Google Scholar
Sánchez, R.A. and de Miguel, L. (1985). The effect of red light, ABA and K+ on the growth rate of Datura ferox embryos and its relations with the photocontrol of germination. Botanical Gazette 146, 472–476.CrossRefGoogle Scholar
Sánchez, R.A. and de Miguel, L. (1992). Phytochrome-induced germination, endosperm softening and embryo growth potential in Datura ferox seeds: sensitivity to low water potential and time to escape to FR reversal. Journal of Experimental Botany 43, 969–974.Google Scholar
Sánchez, R.A., Sunell, L., Labavitch, J. and Bonner, B.A. (1990). Changes in endosperm cell walls of two Datura species before radicle protrusion. Plant Physiology 93, 89–97.CrossRefGoogle ScholarPubMed
Soriano, A., Sánchez, R. and Eilberg, B.A. (1964). Factors and processes in the germination of Datura ferox L. Canadian Journal of Botany 42, 1189–1203.CrossRefGoogle Scholar
Toyomasu, T., Tsuji, H., Yamane, H., Nakayama, M., Yamaguchi, I., Murofushi, N., Takahashi, N. and Inoue, Y. (1993). Light effects on endogenous levels of gibberellins in photoblastic lettuce seeds. Journal of Plant Growth Regulation 12, 85–90.CrossRefGoogle Scholar
Watkins, J.T. and Cantliffe, D.J. (1983). Mechanical resistance of the seed coat and endosperm during germination of Capsicum annuum at low temperature. Plant Physiology 72, 146–150.CrossRefGoogle ScholarPubMed