CARBOHYDRATE CONTENT AND GLYCOSIDASE ACTIVITIES FOLLOWING COLD HARDENING IN 2 GRASS SPECIES

The freezing resistance of the grass species Phleum pratense L. (timot hy) and Phalaris arundinacea L. increases significantly after cold har dening. The content and composition of soluble carbohydrates were dete rmined in the plants after short day treatment, cold hardening and deh ardening. The amounts of mono-, di- and trisaccharides were reduced du ring the short day treatment, increased during cold hardening and decr eased again during dehardening. The total amounts of soluble carbohydr ates (mono-, di-, tri- and polysaccharides) were the same in hardened and dehardened plants, indicating that during hardening soluble polysa ccharides (fructose polymers, fructans) were converted to mono- and ol igosaccharides. Sucrose increased most after hardening conditions and, in P. arundinacea, a significant increase in 1-F-fructosylsucrose (is okestose) was also observed. Invertase (8-fructofuranosidase, EC 3.2.1 .26) activity increased following cold hardening and decreased followi ng dehardening, while the alpha-galactosidase (EC 3.2.1.22) activity s eemed to increase after dehardening. The glycosidases are probably inv olved in the mobilisation of polysaccharides during cold hardening.