Wounding lettuce (Lactuca sativa L., var. Longifolia) leaves induced an eight-fold increase in the activity of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), and the subsequent accumulation of phenolic compounds and tissue browning at 10 C. PAL is a key enzyme in the synthesis of phenolic compounds. A PAL cDNA was previously isolated by reverse-transcription PCR using total RNA from wounded let...