Ethylene as an Effector of Wound-Induced Resistance to Cellulase in Oat Leaves

Peeling the abaxial epidermis from oat leaves (Avena sativa var. Victory) induces the formation of wound ethylene and the development of resistance to cellulolytic digestion of mesophyll cell walls. Ethylene release begins between 1 and 2 hours after peeling in the light or dark. Aminoethoxyvinylglycine (AVG, 0.1 millimolar), CoCl(2) (1.0 millimolar), propyl gallate (PG, 1.0 millimolar) or aminooxyacetic acid (AOA, 1.0 millimolar) inhibits, whereas AgNO(3) stimulates wound ethylene formation. Incubation on inhibitors of ethylene biosynthesis (AVG, CoCl(2), PG, AOA) or action (AgNO(3), hypobaric pressure or the trapping of ethylene with HgClO(4)) also prevents the development of wound-induced resistance to enzymic cell wall digestion. 1-Aminocyclopropane-1-carboxylic acid (ACC, 1.0 millimolar) reverses AVG (0.1 millimolar) inhibition of the development of resistance. Exogenous ethylene partially induces the development of resistance in unwounded oat leaves.These results suggest that peeling of oat leaves induces ethylene biosynthesis, which in turn effects changes in the mesophyll cells resulting in the development of resistance to cellulolytic digestion.