Planta

, Volume 201, Issue 2, pp 128–137

Purification, characterization and physiological role of sucrose synthase in the pea seed coat (Pisum sativum L.)

  • A. Déjardin
  • C. Rochat
  • S. Maugenest
  • J. -P. Boutin
Article

DOI: 10.1007/BF01007697

Cite this article as:
Déjardin, A., Rochat, C., Maugenest, S. et al. Planta (1997) 201: 128. doi:10.1007/BF01007697

Abstract

The seed coat is a maternal organ which surrounds the embryo and is involved in the control of its nutrition. This study with pea (Pisum sativum L.) was conducted to understand more fully the sucrose/starch interconversions occurring in the seed coat. The concentrations of soluble sugars, the starch content, and the activities of the sucrose-metabolizing enzymes, sucrose synthase (Sus; EC 2.4.1.13), alkaline and soluble acid invertase (EC 3.2.1.26) and sucrose-phosphate synthase (SPS; EC 2.4.1.14) were compared at four developmental stages during seed filling. Among the four enzymes, only Sus activity was very high and strongly correlated with the starch concentration in the seed coat. Sucrose synthase catalyses the cleavage of sucrose in the presence of UDP into UDP-glucose and fructose. Sucrose synthase was purified from pea seed coats in a three-step protocol, consisting of diethylaminoethyl-Sephacel chromatography, gel filtration and affinity chromatography. The enzyme was characterized at the biochemical and molecular levels. Sucrose synthase exhibits biochemical properties which allow it to function in the direction of both sucrose cleavage and synthesis. The mass-action ratio of its four substrates was close to the theoretical equilibrium constant at the four developmental stages we studied. A labelling experiment on seed coats has shown that Sus activity is reversible in vivo and can produce 37% of neosynthesized sucrose in the seed coat cells (minimum value). It is concluded that Sus could play a central role in the control of sucrose concentration in the seed coat cells in response to the demand for sucrose in the embryo during the development of the seed.

Key words

Pisum Seed coat Sucrose Sucrose-metabolizing enzymes Sucrose synthase Starch 

Abbreviations

DEAE

diethylaminoethyl

Ki

inhibition constant

RT-PCR

reverse transcriptase-polymerase chain reaction

UDPGlc

UDP-glucose

Sus

sucrose synthase

SPS

sucrose-phosphate synthase

Copyright information

© Springer-Verlag 1997

Authors and Affiliations

  • A. Déjardin
    • 1
  • C. Rochat
    • 1
  • S. Maugenest
    • 1
  • J. -P. Boutin
    • 1
  1. 1.Laboratoire du Métabolisme et de la Nutrition des PlantesINRAVersailles cedexFrance
  2. 2.Biologie des SemencesINRAVersailles cedexFrance

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