Elicitation of capsidiol synthesis in chilli roots by Trichoderma spp. and induced resistance to root-rot pathogen Rhizoctonia solani.

摘要

The induction of capsidiol accumulation by Trichoderma spp. (T. viride, T. longibrachiatum, T. harzianum and T. aureoviride) was studied in roots of 4 chilli (Capsicum) cultivars susceptible (Selection 5 and California Wonder) or resistant (CA960 and Achari) to R. solani. Seeds were sown in pots with soil that had been inoculated with the Trichoderma sp. (50 g per pot). The resultant 30-day-old seedlings were then inoculated with a sclerotial suspension of R. solani. Root samples were analysed for capsidiol at 24 h after pathogen inoculation. The population of T. viride in California Wonder was the greatest, followed by T. aureoviride on Achari. The Trichoderma spp. significantly reduced the population of R. solani from 47.6-57.7 sclerotia/g of soil in the control to 27.5-33.5 sclerotia/g of soil. All the Trichoderma spp. increased the accumulation of capsidiol in chilli roots, with T. harzianum being the most effective, followed by T. longibrachiatum. The interactions between the Trichoderma sp. and chilli cultivar were significant with regard to R. solani population and capsidiol accumulation. The antifungal activity of capsidiol (0.50, 1.25, 3.75 or 5.0 mM) was evaluated against R. solani in vitro. The inhibition of mycelial growth increased as the capsidiol concentration increased.