Wound Signal Receptor DNA mRNA Protein synthesis PAL Phenylpropanoid metabolism Receptor DNA mRNA Protein synthesis PAL-IF Preexisting phenolics Vacuole PPO POD Cellular membranes Phenolics Tissue browning Increased permeability
0 20 40 60 80 100 Time Relative values Wound signal PAL activity PAL inactivating factor Phenolic compounds
Heat-shock proteins Heat-shock Protein synthesis “Normal” General “Signal”
Could the linear sequence of metabolic events induced by one stress (e.g., wounding) be redirected by another abiotic stress (e.g., heat-shock)?
PAL Heat-shock proteins Heat-shock Protein synthesis “Normal” Wounding Signal “Signal” General
Heat-shock Wounding (e.g., of lettuce) PAL Phenolics accumulate Few phenolic compounds present Very little browning Normal conditions X Browning Signal No wound signal remaining Synthesis of HSPs Recovery from the heat-shock and resumption of normal protein synthesis
It appears that one stress (heat (heat shock) shock) can redirect and modify the response of another stress (wounding)
Chilling Injury is Another Stress that is Thought to Occur Through a Linear Sequence of Events