The effect of bioagent treatment in plants not inoculated with
a pathogen offers a practical way of immunizing plants against
biotic stress (Jones and Dangl, 2006). In the present study, isolates
vh6 and vh8 were effective in inducing resistance in tomato plants
in the presence of R. solani. Based on the HPLC analysis of phenolic
acids particularly gallic, ferulic, cinnamic, genteisic, chlorogenic and
salicylic acids revealed that isolates vh6 and vh8 which provided
significant protection of tomato plant against the pathogen (Fig. 4)
also showed the highest accumulation of these compounds.