Categories of Petal Senescence and Abscission: A Re-evaluation

In a previous paper (Woltering and van Doorn, 1988, Journal of Experimental Botany39: 1605–1616) we identified three types of flower life cessation: by petal wilting or withering, which was either ethylene-sensitive or insensitive, and by abscission of turgid petals, which was ethylene-sensitive. These categories tended to be consistent within families. Here we re-examine these relationships by testing a further 200 species, and a number of other families. As previously, flowering shoots were exposed to 3 ppm ethylene for 24 h at 20 °C, in darkness. Most monocotyledonous species tested showed ethylene-insensitive petal wilting, although ethylene-sensitive wilting occurred in the Alismataceae and Commelinaceae. Petals of the dicotyledonous species tested were generally sensitive to ethylene, except for a few groups showing wilting (Crassulaceae, Gentianaceae and Fumariaceae, and one subfamily in both the Ericaceae and Saxifragaceae). Petal abscission was generally ethylene-sensitive, but ethylene insensitivity was found in some Tulipa cultivars and three Saxifraga species. In most tulip cultivars tested, the petals wilted and then fell. It is concluded that (a) the response to ethylene is often consistent within either families or subfamilies; and (b) a fourth category, ethylene-insensitive petal abscission, exists both in monocotyledons and dicotyledons.