Induced changes in phenolic acids and stilbenes in embryogenic cell cultures of Norway spruce by culture filtrate of Ascocalyx abietina

The aim of this work was to identify whether the Ascocalyx abietina culture filtrate has the ability to induce changes in the contents of phenolic substances that might be indicative for the disease response of Norway spruce (Picea abies). We focused on the accumulation of soluble and cell wall-bound phenolics, stilbenes as well as extracellular peroxidase activities elicited in the embryogenic cell cultures of Norway spruce by A. abietina culture filtrate. Treatment of spruce cells with fungal culture filtrate (5 and 20% v/v concentrations) evoked an increase in the total contents of phenolic acids (represented by the sum of free, methanol soluble ester- and glycoside-bound phenolics and methanol insoluble cell-wall bound phenolic esters). The challenge with filtrate was in particular manifested in the increase (compared with the control) in the contents of cell wall-bound phenolic acids (by about 100 and 130% in 5 and 20% filtrate, respectively) and soluble phenolic glycosides (by 37 and 65% in 5 and 20% filtrate, respectively) already 6 h after filtrate addition. Significantly decreased concentrations of stilbene glycosides, isorhapontin, astringin and piceid, were determined in filtrate-treated spruce cell cultures 6 and 12 h after filtrate addition. The culture filtrate did not influence significantly the extracellular peroxidase activity 12 h after filtrate addition. Reduced extracellular peroxidase activity at 24 and 48 h in treated cells and decline in the amounts of soluble phenolics coincided with the rate of browning of filtrate-treated cells.