Analysis of Ethylene and ACC in Lichens

Much research has been done on plant hormones in higher plants, where they play a fundamental role in regulating plant growth, development and reproduction (Davies 1995). In addition, in lichens interactions between the mycobiont and the photobiont require regulation (Jahns and Ott 1990). Plant hormones are a group of natural organic substances that affect physiological processes at low concentrations. Auxins, cytokinins, gibberellins, abscisic acid and ethylene, as well as polyamines, jasmonates, salicylic acid and brassinosteroids are biologically effective substances widespread in higher plants. However, information on the role of these substances in algae and fungi is very limited. Plant hormones have been identified in a range of different lichens (Ott and Zwoch 1992). Indole acetic acid (IAA), abscisic acid (ABA) and ethylene have been discovered in several lichen species. For example, IAA and ethylene have been detected in Ramalina duriaei (Epstein et al. 1986, Lurie and Garty 1991), and ABA in Ramalina maciformis (Hartung and Gimmler 1994). Of these plant hormones, only the gaseous substance ethylene has been examined in detail (Garty et al. 1995, Ott and Schieleit 1994, Ott 1993).