Growth Inhibition of Intact Plants and In Vitro Cultures of Tobacco by Culture Filtrates of Fusarium oxysporum f.sp. nicotianae

The culture filtrate of Fusarium oxysporum was able to induceseveral symptoms on tobacco plants that appeared during theactual pathological condition. Positive correlations were establishedfor the degree of culture-filtrate-induced symptoms developedin a range of tobacco cultivars and those caused by the livepathogen after inoculation into the same cultivars. Effectsof culture filtrate on the growth of intact plants, anthers,leaf discs and cell suspensions were examined to assist in understandingthe cellular basis of pathogenicity. The culture filtrate above25 % (v/v) was found inhibitory to the growth of leaf-disesand plated cell suspensions. No growth occurred above the 50%(v/v) level of the filtrate. Similarly, wilt symptoms were observedon the whole plants when the culture filtrate exceeded 25% (v/v).In vitro androgenesis was inhibited at a much lower concentration(12.5% v/v) of culture filtrate. Fusarium oxysporum f.sp, nicotianae, Nicotiana tabacum, fungal culture filtrate, will disease