An Elicitor of the Hypersensitive Lignification Response in Wheat Leaves Isolated from the Rust Fungus Puccinia graminis f. sp. tritici I. Partial Purification and Characterization

B. Moerschbacher, K. H. Kogel, U. Noll, and H. J. Reisener Institut für Biologie III der RW TH Aachen, W orringer Weg, D-5100 Aachen, Bundesrepublik Deutschland Z. Naturforsch. 41c, 830—838 (1986); received April 4/May 5, 1986 Triticum aestivum, Puccinia graminis f. sp. tritici, Hypersensitive Response, Lignification, Elicitor Several biotic and abiotic elicitors of the hypersensitive reaction in wheat leaves are described. The elicitors induce enhanced activity of phenylalanine ammonia-lyase with subsequent lignifica­ tion, visible as a yellow autofluorescence. The deposited material stains positively with phloroglucinol. DEA E-dextran, epoxystearic acid and chitosan are strong elicitors, while the glucans tested have no activity. A biotic elicitor (genuine Pgr-elicitor) was isolated from the germ tube walls of uredospores of Puccinia graminis f. sp. tritici. The high molecular weight, water soluble elicitor is heat stable and unaffected by mild acid and mild alkaline treatm ents. It seems to be a glycoprotein with the carbohydrate moiety bearing the active residues, as indicated by periodate sensitivity and pro­ tease stability. The carbohydrate moiety consists mainly of glucose with some galactose and mannose. Upon ultrafiltration and gel chrom atography elicitor activity was associated with fractions of molecular weight of more than 100 kD. When injected into the intercellular space of primary wheat leaves, the elicitor induces lignifica­ tion, preceded by an increase in phenylalanine ammonia-lyase activity.