Interaction of Methyl Jasmonate and Ethephon in Gum Formation in Tulip Bulbs

Abstract

Gums are induced by Fusarium oxysporum f. sp. tulipae in tulip bulbs, in which a relatively high level of ethylene is produced. Exogenous ethylene or ethylene-releasing compound (ethephon) also induced gummosis in healthy tulip bulbs but not in other organs, such as stem and leaves. Methyl jasmonate (JA-Me) applied alone a a lanolin paste induced gum formation in tulip bulbs, stem and basal part of leaves. Ethephon applied simultaneously with JA-Me greatly enhanced gum formation in tulip bulbs, independently of the time of the treatment, for example gum production in tulip bulbs treated on September 10, exceeded 153mg of dry weight with JA-Me 1.00/0, 17mg with ethephon 2.00/0 and 1206mg with JA-Me 1 .Oo/o +ethephon 2.00/0. After about 4 months any gununosis was observed in each treatment. These results suggest that the induction and/or the production of gums are regulated by a signal network of methyl jasmonate and ethylene, especially by their cross talk. Interactions between endogenous jasmonate and ethylene and gene(s) expression responsible for gum biosynthesis are also discussed.