Resistance against Fusarium Wilt Induced by Non-Pathogenic Fusarium in Ipomoea tricolor

Abstract

The cuttings of morning glory seedlings (Ipomoea tricolor cv. heavenly blue) were susceptible to Fusarium oxysporum f. sp. batatas (PF), and showed the typical fusarium wilt symptom. By using the reduction of chlorophyll content in cotyledons as the quantitative index of the disease symptom, we found that the pretreatment with the non-pathogenic isolate of Fusarium (NPF; F. oxysporum 101–2), which has been practically used as a biological control agent for fusarium wilt of sweet potato, suppresses the symptom significantly. Dead NPF bud-cells could not induce resistance. The supernatant of NPF culture after centrifugation at 15,000 × g for 20 min, also induced resistance. The activity of the supernatant was lost by heating. The factor(s) associated with the induction of resistance was considered to be thermolabile chemical component(s) produced by NPF. This experimental model may be facile and useful for analyzing the chemical basis of the biological interaction among PF, morning glory and NPF. © 2000, Pesticide Science Society of Japan. All rights reserved.