Plant Disease Resistance Inducing Activity of 7-Oxo- and 7-Hydroxysterols

The 7-oxosterols 1–2 and the 7-hydroxysterols 3–6 induce resistance toward the fungal pathogens Puccinia striiformis West, and Puccinia hordei 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) followed, 2 days later, by challenge inoculation with the fungal pathogens. The results indicate that 7a- and 7β-hydroxylated epimers of β-sitosterol and cholesterol show the highest value of induced resistance (39-49% reduction of infection sites). No enhanced resistance toward the fungi Erysiphe graminis DC f. sp. tritici and hordei and Cochliobolus sativus Ito & Kuribayashi was observed. © 1995 Verlag der Zeitschrift für Naturforschung. All rights reserved