PLANT-DISEASE RESISTANCE INDUCING ACTIVITY OF 7-OXOSTEROLS AND 7-HYDROXYSTEROLS

The 7-oxosterols 1-2 and the 7-hydroxysterols 3-6 induce resistance to ward the fungal pathogens Puccinia striiformis West. and Puccinia hord ei Otth in barley and wheat. Primary leaves of the plants were sprayed with solutions of the compounds (10(-4) mol/l in 1% aqu. ethanol) fol lowed, 2 days later, by challenge inoculation with the fungal pathogen s. The results indicate that 7 alpha- and 7 beta-hydroxylated epimers of beta-sitosterol and cholesterol show the highest value of induced r esistance (39-49% reduction of infection sites). No enhanced resistanc e toward the fungi Erysiphe graminis DC f. sp. tritici and hordei and Cochliobolus sativus Ito & Kuribayashi was observed.