One of the early responses of plants to microbes is the induction of ethylene biosynthesis. This and other responses are initiated by components produced by the microbe called "elicitors". One such elicitor, an ethylene biosynthesis-inducing endoxylanase (EIX) from Trichoderma viride, elicits several responses in tomato that are characteristic of a hypersensitive response. The objective of our research is to better understand the role of ethylene in EIX-induced responses. 1-Methylcyclopropene (1-MCP), an inhibitor of ethylene action, is thought to bind to ethylene receptors and thereby block tomatoes from responding to the hormone [E. Sisler, personal communication]. Tomato plants incubated in an atmosphere of 0.1 nL/L 1-MCP prevents the epinastic response seen with tomatoes subsequently incubated in 10 nL/L ethylene without inhibitor. Detached leaves of tomato treated with 1 ug of EIX respond by producing ethylene. Ethylene production by EIX-treated tissues is stimulated several-fold if the tissue is ethylene pretreated (24h) or incubated with 1-MCP. The increased production of ethylene observed in 1-MCP- and EIX-treated tissues may involve the disruption of a feedback-type regulation of one or more steps in the ethylene biosynthesis pathway. In addition to the effect on EIX-induced ethylene biosynthesis, 1-MCP seems to inhibit the onset of tissue necrosis induced by EIX. Further studies with 1-MCP will hopefully clarify the role of ethylene in EIX-induced responses such as necrosis and ethylene biosynthesis.
Use of the ethylene-action inhibitor, 1-methylcyclopropene, to study the role of ethylene in elicitor-induced ethylene biosynthesis in tomato leaves
CARDINALE, Francesca;
1995-01-01
Abstract
One of the early responses of plants to microbes is the induction of ethylene biosynthesis. This and other responses are initiated by components produced by the microbe called "elicitors". One such elicitor, an ethylene biosynthesis-inducing endoxylanase (EIX) from Trichoderma viride, elicits several responses in tomato that are characteristic of a hypersensitive response. The objective of our research is to better understand the role of ethylene in EIX-induced responses. 1-Methylcyclopropene (1-MCP), an inhibitor of ethylene action, is thought to bind to ethylene receptors and thereby block tomatoes from responding to the hormone [E. Sisler, personal communication]. Tomato plants incubated in an atmosphere of 0.1 nL/L 1-MCP prevents the epinastic response seen with tomatoes subsequently incubated in 10 nL/L ethylene without inhibitor. Detached leaves of tomato treated with 1 ug of EIX respond by producing ethylene. Ethylene production by EIX-treated tissues is stimulated several-fold if the tissue is ethylene pretreated (24h) or incubated with 1-MCP. The increased production of ethylene observed in 1-MCP- and EIX-treated tissues may involve the disruption of a feedback-type regulation of one or more steps in the ethylene biosynthesis pathway. In addition to the effect on EIX-induced ethylene biosynthesis, 1-MCP seems to inhibit the onset of tissue necrosis induced by EIX. Further studies with 1-MCP will hopefully clarify the role of ethylene in EIX-induced responses such as necrosis and ethylene biosynthesis.
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