Wound-induced Proteinase Inhibitor in Tomato Leaves

Abstract

Wounding of single leaflets of young tomato (Lycopersicum esculentum var. Bonnie Best) plants causes the release of a proteinase inhibitor inducing factor. This factor is rapidly transported throughout the plant where it causes accumulation of inhibitor I, a potent inhibitor of several serine proteinases from both animals and microorganisms. The wound-induced accumulation of inhibitor I is both light- and temperature-dependent. In total darkness no accumulation results from wounding. The accumulation exhibits a linear dependence upon light up to 300 foot candles. At 600 foot candles and above, the response is maximal. In light the wound response possesses an unusual temperature dependence with an optimum rate of accumulation near 36 C. Below 20 C no accumulation occurs. The over-all process contains two light- and temperature-dependent steps, one involving wounding and transport, the other involving accumulation.