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

Abstract

The culture filtrate of Fusarium oxysporum was able to induce several symptoms on tobacco plants that appeared during the actual pathological condition. Positive correlations were established for the degree of culture-filtrate-induced symptoms developed in a range of tobacco cultivars and those caused by the live pathogen after inoculation into the same cultivars. Effects of culture filtrate on the growth of intact plants, anthers, leaf discs and cell suspensions were examined to assist in understanding the cellular basis of pathogenicity. The culture filtrate above 25 % (v/v) was found inhibitory to the growth of leaf-dises and plated cell suspensions. No growth occurred above the 50% (v/v) level of the filtrate. Similarly, wilt symptoms were observed on 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.