Jasmonates: Metabolism, Biological Activities, and Modes of Action in Senescence and Stress Responses

First detected as fragrant constituents of the essential oils ofJasminum(Demoleet al.1962) andRosmarinum(Crabalona, 1967), (—)-jasmonic acid (JA) and its methyl ester (JA-Me) became of interest for plant physiologists after the first observations on growth inhibition (Yamaneet al.1980) and leaf senescence promotion (Ueda and Kato, 1980). In recent years many more physiological processes were found to be influenced by these cyclopentanone compounds. Thus, in combination with the ubiquitous occurrence in plants and a low dose — activity relationship, it seems justified to coordinate jasmonates to the “classical” five phytohormone groups, distinguished by the conception of being natural regulators in plant growth and development.