Isolation of pathogen-synthesized fraction that elicits phytoalexins in lucerne (Medicago sativa L.).

The production of phytoalexins by lucerne cultivars Dupuits (susceptible to Verticillium wilt) and Maris Kabul (resistant to Verticillum wilt) in response to substances (= elicitors) produced by pathogenic and non-pathogenic isolates of Verticillium albo-atrum was investigated. The elicitors are produced in culture filtrates from log-phase and past log-phase stages. The elicitors were isolated by gel-filtration and found to contain both protein and carbohydrate. They were found to be thermostable and non-dialyzable and proved to be sensitive to protease and sodium hydroxide treatment which suggests that they are glycoproteins. There was no evidence of specificity of the elicitors.