XYLANASE TREATMENT OF PLANT-CELLS INDUCES GLYCOSYLATION AND FATTY ACYLATION OF PHYTOSTEROLS

Treatment of tobacco suspension cells (Nicotiana tabacum cv. KY 14) wi th a purified beta-1,4-endoxylanase from Trichoderma viride [1 mu g en zyme (ml cells)(-1)] caused a 13-fold increase in the levels of acylat ed sterol glycosides and elicited the synthesis of phytoalexins. A com mercial preparation of xylanase from Trichoderma viride caused an iden tical shift in sterols. In contrast, a commercial xylanase from Aureob asidium pullulans had no effect on the levels of acylated sterol glyco sides, but did elevate the levels of sterol esters. Treatment of the c ells with Cu2+ or Ag+ also evoked a severalfold increase in the levels of acylated sterol glycosides. Analysis of the various sterol lipid c lasses revealed that the large xylanase-induced increase in acylated s terol glycosides occurred at the expense of sterol esters, free sterol s and sterol glycosides. Further analyses revealed that the most abund ant phytosterol in each of the four classes of sterol lipids was beta- sitosterol. Linoleic acid was the most abundant fatty acid in the ster ol eaters, and palmitic and linoleic acids were the most abundant fatt y acids in the acylated sterol glycosides. Glucose was the only sugar moiety in the sterol glycoside and acylated sterol glycoside fractions . The results of the present study demonstrate that xylanase from Tric hoderma viride induces a dramatic shift in the level of acylated stero l glycosides, indicating that endoxylanase was probably the active com ponent in the cellulase enzyme preparations used in our previous study .