Saponin distribution in the etiolated leaf tissue and subcellular localization of steroidal saponins in etiolated protoplasts of oat (Avena sativa L.)

Sterols and sterylglycosides of oats (Avena sativa). Distribution in the leaf tissue and medium‐induced glycosylation of sterols during protoplast isolation

“…Concerning the possible reason for the loss of sterols, leakage from the mesophyll cells during isolation could be ruled out, since the recovery of galactolipids was HO-100% and that of saponins 33% (Tab, 2), This latter value is in accordance with earlier results obtained for intact protoplasts Urban 1983, Urban et al, 1983). In contrast to the sterol deficit, the recovery of ASG in isolated protoplasts was up to 134% and that of SG up to 100% of the leaf value (Tab.…”

“…Plantarum 70, 1987 Such a concept would not only be in accordance with the medium-induced glycosyiation, but also with the present view of the intracellular distribution of sterols and sterol glycosyltransferase, Gronewald et al, (1982), Hartmann et al, (1975Hartmann et al, ( , 1977 and Hodges et al, (1972) have all shown that sterols are concentrated in the plasmalemma. Hartmann-Bouillon et al (1979) have also found that the activity of UDP-glucose;sterol glucosyltransferase is concentrated in the same compartment, although other authors (Lercher andWojciechowski 1976, Bowles et al, 1977) have localized the enzyme in Golgi membranes. In our labelling experiments, the label was mainly localized in ASG (Tab, 4); this means that the newly synthesized SG is acylated to a great extent.…”