Planta

, 223:90

Fructan:fructan 1-fructosyltransferase, a key enzyme for biosynthesis of graminan oligomers in hardened wheat

Original Article

DOI: 10.1007/s00425-005-0054-6

Cite this article as:
Kawakami, A. & Yoshida, M. Planta (2005) 223: 90. doi:10.1007/s00425-005-0054-6

Abstract

Fructans play important roles not only as a carbon source for survival under persistent snow cover but also as agents that protect against various stresses in overwintering plants. Complex fructans having both ß-(2,1)- and ß-(2,6)-linked fructosyl units accumulate in wheat (Triticum aestivum L.) during cold hardening. We detected fructan: fructan 1-fructosyltransferase (1-FFT; EC 2.4.1.100) activity for catalyzing the formation and extension of ß-(2,1)-linked fructans in hardened wheat tissues, cloned cDNAs (wft3 and wft4) of 1-FFT, and analyzed the enzymatic properties of a wft3 recombinant protein (Wft3m) produced by yeast. Wft3m transferred ß-(2,1)-linked fructosyl units to phlein, an extension of sucrose through ß-(2,6)-linked fructosyl units, as well as to inulin, an extension of sucrose through ß-(2,1)-linked fructosyl units, but could not efficiently synthesize long inulin oligomers. Incubation of a mixture of Wft3m and another recombinant protein of wheat, sucrose:fructan 6-fructosyltransferase (6-SFT), with sucrose and 1-kestotriose produced fructans similar to those that accumulated in hardened wheat tissues. The results demonstrate that 1-FFT produces branches of ß-(2,1)-linked fructosyl units to phlein and graminan oligomers synthesized by 6-SFT and contributes to accumulation of fructans containing ß-(2,1)- and ß-(2,6)-linked fructosyl units. In combination with sucrose:sucrose 1-fructosyltransferase (1-SST; EC 2.4.1.99) and 6-SFT, 1-FFT is necessary for fructan synthesis in hardened wheat.

Keywords

FructanGraminan biosynthesisWinter wheatCold hardeningFructan:fructan 1-fructosyltransferaseTriticum aestivum

Abbreviations

1-SST

Sucrose:sucrose 1fructosyltransferase

1-FFT

Fructan:fructan 1-fructosyltransferase

6-SFT

Sucrose:fructan 6-fructosyltransferase

6G-FFT

Fructan:fructan 6G-fructosyltransferase

FEH

Fructan exohydrolase

HPAEC

High-performance anion exchange chromatography

PAD

Pulsed amperometric detector

DP

Degree of polymerization

Wft1

Wheat fructosyltransferase 1

Wft3

Wheat fructosyltransferase 3

Wft4

Wheat fructosyltransferase 4

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Laboratory of Fungal Disease, Department of Plant PathologyNational Agricultural Research CenterIbarakiJapan
  2. 2.Laboratory of Winter Stress, Department of Low Temperature ScienceNational Agricultural Research Center for Hokkaido RegionHokkaidoJapan