Abstract
Water-soluble extracellular materials from germlings of Erysiphe graminis f. sp. hordei (a pathogen of barley) suppressed infection by the fungus in barley coleoptiles by 23-54% depending on the concentrations applied. The suppressive activity was associated with a low molecular weight (<10, 000), heat-stable moiety. The extract preparation was separated into five fractions by HPLC. When applied to lower sides of coleoptiles, only one fraction suppressed infection by E. graminis inoculated upper sides of the coleoptiles by about 60%. These suppressive extracts were obtained from conidia and germlings incubated on cellulose membranes 0-12 hr after inoculation, suggesting that conidia of the fungus might constitutively have the elicitor component(s) which could direct barley cells towards the inaccessible state to this fungus.
