Induction of defence responses in cultured tobacco cells by elicitors from Phytophthora nicotanae

Abstract

Black Sbank disease of tobacco, Nicodanae tabacum, caused by Pkytopathora nicotianae, is one of the most eve of soil borne diseases. The present investiption was initiated to study the relative importance of various inducible mechanisms operative in this plant:pathogen interaction. Tobacco cell is culture were treated with beat-released soluble cell-wall elicitors from myceiial walls of the pathogen. The timing and intensity of the induced defence responses of the cells with regard to the synthesis of pbytoalexins, lignin and defence hydrolases were evaluated. An elicitor concentration of 40 μg ml −1 resulted in the optimal induction of sesguiterpenoid pbytoslexin synthesis which was detectable 3–4 hr after elicitation and reached a maximum at 20–28 hr post-elicitation. Increased lignin deposition was detectable 4 hr after elicitation with maximal synthesis between 12 and % hr. Induction of extraceffrdar and cellular β-1,3-glucauases was observed within 4 hr, exhibiting a biphasic response with an initial peak at 8–12 h. Increased cellular and echltimse activities were detected from 8 and 16 hr onwards, respect ively. These results were supported by enzyme staining of electropboretk separated isoforms. The rests obtained indicate that the elicitation of tobacco cells by P. nicotianae derived sigioal molecules exhibits the properties of a multicomponent dynamic system with different protective mechanisms wing complementary roles in the overall expression of the defence response.