| Popis: |
Summary An elicitor preparation consisting of glycopeptides partially purified from yeast extract and the membrane- perturbing agents chitosan and digitonin were compared with respect to their effects on ethylene biosynthesis, phenylalanine ammonia-lyase (PAL) activity and callose formation in tomato cells. The yeast-derived elicitor strongly induced ethylene biosynthesis and PAL activity. The two responses were closely correlated but independent since exogenous ethylene did not induce PAL and since cobalt ions, although completely inhibiting induction of ethylene biosynthesis, did not affect elicitor-dependent induction of PAL. The yeast-derived elicitor did not induce callose formation. Chitosan and digitonin, on the other hand, strongly induced callose formation and considerably induced PAL activity but stimulated ethylene biosynthesis only weakly. When these compounds were added in combination with yeast-derived elicitor, all responses were fully induced, indicating that none of the stimuli inhibited the response to the others. The induction of ethylene biosynthesis and PAL activity by the various stimuli was completely blocked by the protein kinase inhibitor, K-252a, while induction of callose formation was not inhibited. |
