Figure 1.

The generation of H₂O₂ in leaves of tomato plants in response to wounding and wound signals. Fourteen-day-old plants were excised at the base of the stems and supplied with DAB for 8 hr. The plants then were either wounded, supplied with solutions of systemin, OGA, or chitosan in DAB through the cut stems, or exposed to MJ vapors in a closed Plexiglas box as described in Materials and Methods. (A) The time course of H₂O₂ production in tomato leaves in response to wounding. (B) The systemic production of H₂O₂ in leaves of tomato plants wounded only on the lower leaf. (C) The production of H₂O₂ in leaves of tomato plants 4 hr after treatment with systemin (SYS), OGA, chitosan (CHIT), or MJ.