Host-Pathogen Interactions

Abstract

The glucan elicitor isolated from the mycelial wails of Phytophthora megasperma var. sojae, the fungus which causes stem and root rot in soybeans, stimulates the activity of phenylalanine ammonia-lyase and the accumulation of glyceolUn in suspension-cultured soybean cells.

Host-pathogen interactions in plants. Plants, when exposed to oligosaccharides of fungal origin, defend themselves by accumulating antibiotics.

“…17) (5), the hypocotyl assay ( Fig. 18) (5), and the cell suspension-culture assay (20). All three assays give the same results, that is, the activities of the elicitors from different Pms races are identical (7).…”

“…8) 3 h after exposure of the suspension-cultured cells to the elicitor (20). The increase in activity of the phenylalanine ammonialyase in soybean cell suspension cultures treated with elicitors is followed by the accumulation of glyceollin (Fig.…”

“…2). A third assay for elicitors involves the stimulation of the activity of phenylalanine ammonia-lyase and the accumulation of glyceollin in suspension-cultured soybean cells (20). This assay does not depend on wounding of the soybean tissues.…”

“…The elicitor molecules are heterogeneous in size, ranging from a mol wt of -5,000 to -200,000. The elicitor lacks ionizable groups, as the elicitor does not bind to anion and cation exchange columns under a vari- (20). (Fig.…”

“…Indeed, a series of r, commercially available polysaccharides, oligosac--charides, methylglycosides, and simple sugars have been tested for elicitor activity, and, besides laminarin, the only commercially available product found with detectable elicitor activity was nigeran, a mycelial wall glucan from the fungus, Aspergillus niger (20).…”