Touch-Sensitive NADH Oxidase Activity of Pea and Cucumber Tendrils and Soybean Hypocotyl Sections

The cell surface reduced nicotinamide adenine dinucleotide (NADH) oxidase activity of soybean stems and of pea and cucumber tendrils responded to touch with a several-fold increase in activity. The increase in NADH oxidase persisted for 20 min or longer, and further touch stimulation during this period did not alter activity. With soybean sections, the specific activities in response to touch approximated those achieved maximally by auxin. Where the NADH oxidase was fully stimulated by 2,4-d, the NADH oxidase failed to respond further to touch. The findings indicate that the NADH oxidase of the plant cell surface is involved in the growth response to touch and in tendril coiling.