Partial purification and characterization of elicitors for 6-methoxymellein production in cultured carrot cells

6-Methoxymellein production by cultured carrot cells was elicited by the addition of partial hydrolysates of the pectic substances of carrot cells obtained with pectinase or trypsin. The crude elicitor preparations were fractionated by anion exchange and gel filtration chromatography and resolved into several fractions. The elicitors, which had been purified from the pectinase hydrolysate, were almost completely destroyed by a subsequent treatment with pectinase. However, treatment with Pronase E did not have a significant effect on the activity of the same elicitor preparations indicating that the essential constituent of these elicitors is oligouronide. On the other hand, pectic fragments of carrot cells obtained by tryptic digestion contained at least two distinct types of elicitor active component. One of them lost activity after treatment with Pronase E after it was resistant to pectinase. In contrast, the activity of the other elicitor was reduced by pectinase treatment. It is likely that elicitor for phytoalexin production in carrot is not a single molecular species but rather heterogenous pectic fragments containing an essential moiety such as oligouronide or peptide.