Photoacoustic and Photothermal Detection of the Plant Hormone Ethylene

The hydrocarbon ethylene (C₂ H₄ ) is a plant hormone that plays an important role in the regulation of many environmentally and developmentally induced processes, such as stress resistance, seed germination, fruit ripening, senescence, and abscission (1 ). All tissue types and probably all cells of higher plants produce and liberate ethylene (2 ). Many lower plants, such as liverworts, mosses, ferns, lycopods, and horse tails, also are producers of ethylene, although the biosynthetic route seems to be different (2 ,3 ). Tremendous progress has been achieved during the last two decades in the biochemical and molecular characterization of the biosynthetic pathway for ethylene in higher plants (4 ,5 ).