Changes in phenolic acids and stilbenes induced in embryogenic cell cultures of Norway spruce by two fractions of Sirococcus strobilinus mycelia

Abstract

We examined defence responses in embryogenic cell suspension cultures of Norway spruce (Picea abies [L.] Karst) elicited by intracellular protein and cell wall fractions (PF and WF, respectively) prepared from mycelia of the fungus Sirococcus strobilinus Preuss focusing on changes in (soluble and cell wall-bound) phenolic and stilbene concentrations. Treatment with both preparations induced an increase in the total contents of phenolic acids in Norway spruce cells and variations in the levels of stilbene glycosides. More rapid and intense induction of defence response was observed in cells after WF application. The contents of soluble phenolic acids (especially benzoic acid derivatives) and cell wall-bound phenolic acids (especially ferulic acid) started to increase (relative to controls) within 4 h after the addition of the WF preparation and remained high in elicited cells for 8-12 h. A moderate increase in phenolic acids in cells exposed to the PF preparation was observed within 8 h after application. However, after 24 h of WF treatment a decline of total phenolics was observed, while in PF elicited Norway spruce cells the phenolic content continued to increase. Significantly decreased concentrations of stilbene glycosides, isorhapontin, astringin and piceid, were determined in PF and WF treated Norway spruce cell cultures. The total content of stilbene glycosides decreased within 8 h after WF application to 68% of the amount determined in the control and within 12 h to 73% of the control in PF-treated cells. These results demonstrate that both PF and WF prepared from the Sirococcus strobilinus mycelium elicit changes in the metabolism of phenylpropanoids, which are involved in the defence responses of plants to pathogens.