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

The effects of tunicamycin, an inhibitor of lipid-linked glycosyl transfer, and swainsonine, an inhibitor of Golgi mannosidase II, on Lupinus albus L. root growth in vitro were studied. SDS-PAGE analysis of total and endomembrane fraction Con A-binding polypeptides from cultured roots indicated that: (i) tunicamycin effectively prevents N-glycosylation of root polypeptides; (ii) swainsonine inhibits Golgi mannosidase II which results in the formation of N-linked oligosaccharides with extra mannose residues. Increases in root length of 26% and 20% were observed when roots were incubated with 5 and 10 mu g/ml tunicamycin, respectively, during 48 h; after this period their growth rate was inhibited. Swainsonine also had a stimulating effect on L. albus root growth during the initial 48 h, for each of the concentrations tested (5, 10 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 sustained 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%).