Oxidative burst and expression of germin/oxo genes during wounding of ryegrass leaf blades: comparison with senescence of leaf sheaths.

Two bursts of H(2)O(2) production have been detected by in situ 3,3'-diaminobenzidine (DAB) staining after cutting of Lolium perenne L. leaf blades. The first burst, which occurred immediately after wounding was inhibited by Na-diethydithiocarbamate (DIECA), a Cu/Zn-superoxide dismutase (SOD) inhibitor.

Fructans, but not the sucrosyl-galactosides, raffinose and loliose, are affected by drought stress in perennial ryegrass.

The aim of this study was to evaluate the putative role of the sucrosyl-galactosides, loliose [alpha-D-Gal (1,3) alpha-D-Glc (1,2) beta-D-Fru] and raffinose [alpha-D-Gal (1,6) alpha-D-Glc (1,2) beta-D-Fru], in drought tolerance of perennial ryegrass and to compare it with that of fructans. To that end, the loliose biosynthetic pathway was first established and shown to operate by a UDP-Gal: sucrose (Suc) 3-galactosyltransferase, tentatively termed loliose synthase. Drought stress increased neither the concentrations of loliose and raffinose nor the activities of loliose synthase and raffinose synthase (EC 2.

Fate of fructose supplied to leaf sheaths after defoliation of Lolium perenne L.: assessment by 13C-fructose labelling.

The role of fructans from leaf sheaths for the refoliation of Lolium perenne after severe defoliation was assessed by following the fate of (13)C-fructose supplied to leaf sheaths at the time of defoliation. At the end of the 4 h labelling period on defoliated plants, 77% of the (13)C incorporated was still located in leaf sheaths. Only 4% and 0.