Anti-tobacco necrosis virus (tnV) activity of xyloglucan fragments in cucumber cotyledons re-examined

We have previously reported (SUBIKOVA er at., this Journal 101, 128-131, 19 94) chat a mixture of oligosaccharide fragments DP 7-9 (XGOS) prepared by p artial enzymatic hydrolysis of xyloglucan by fungal cellulase induced resis tance against tobacco necrosis virus(TNV) infection in cucumber (Cucumis sa tivus L.) cotyledons. However, re-examination of this effect by using caref ully fractionated and purified XGOS did not confirm these observations. Ins tead, the present results have lead us to a conclusion that the active prin ciple in the previously used relatively crude mixtures of XGOS was a contam inating component(s) originating from the Trichoderma cellulase used to hyd rolyze xyloglucan.