Fructan exohydrolase activity in leaves of Lolium temulentum L.

Authors

  • R. J. SIMPSON,

    1. School of Agriculture and Forestry, The University of Melbourne Parkville, 3052, Australia
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  • R. P. WALKER,

    1. Environmental Biology Department, Welsh Plant Breeding Station, AFRC Institute for Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK
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  • C. J. POLLOCK

    1. Environmental Biology Department, Welsh Plant Breeding Station, AFRC Institute for Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK
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summary

Crude extracts from leaves of Lolium temulentum L. exhibited invertase activity and activity capable of releasing fructost from fructans (fructan exohydrolase; FEH), The optimum pH for FEH activity was between pH 4.8 and 5.5. When shoots of 10-d-old seedlings were induced to accumulate fructans by cooling their roots to 5 °C and exposing them to continuous light, FEH activity declined by at least 50 %, FEH activity increased when the shoots were induced to mobilize the fructans by warming the roots to the ambient temperature (20°C) and darkening the plants. Declining activity coincided with loss of one of at least two FEH isoforms observed after starch gel electrophoresis. Partially purified FEH from leaves of L. temulentum was inhibited when assayed in the presence of 10 HIM sucrose.

Abbreviations
DP

degree of polyerization

FEH

fructan exohydrolase

MTT

3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide

PMS

phenazine methosulphate

TLC

thin-lyer chromatography

Ancillary