TUNICAMYCIN AND SWAINSONINE STIMULATE LUPINUS-ALBUS L ROOT-GROWTH IN-VITRO

The effects of tunicamycin, an inhibitor of lipid-linked glycosyl tran sfer, and swainsonine, an inhibitor of Golgi mannosidase II, on Lupinu s albus L. root growth in vitro were studied. SDS-PAGE analysis of tot al and endomembrane fraction Con A-binding polypeptides from cultured roots indicated that: (i) tunicamycin effectively prevents N-glycosyla tion of root polypeptides; (ii) swainsonine inhibits Golgi mannosidase II which results in the formation of N-linked oligosaccharides with e xtra mannose residues. Increases in root length of 26% and 20% were ob served when roots were incubated with 5 and 10 mu g/ml tunicamycin, re spectively, during 48 h; after this period their growth rate was inhib ited. Swainsonine also had a stimulating effect on L. albus root growt h during the initial 48 h, for each of the concentrations tested (5, 1 0 and 15 mu g/ml) showing similar effects on growth (30%, 25% and 32%, respectively). During the following 48-h period (up to 96 h) a sustai ned stimulating effect was observed with 5 and 10 mu g/ml swainsonine (29%), while the 15-mu g/ml dose exerted a much higher stimulation (46 %).