Mutualistic relationships

Essential oils are especially important in mutualistic relationships between plants and insects such as pollination and seed and fruit dissemination (37,45,77-79). In these instances essential oil components serve as attractive substances for the plant. These compounds vary widely in composition but contain most of the chemical types described above. In some cases even volatile amines and skatole are involved, as in the pollination of Sauronatum guttatum (Araceae) (80). 

As an adjunct to the concept of co-evolution, the New Function Hypothesis proposed by Clay (1988) suggests that pathogens may evolve towards a mutualistic relationship with their hosts through the appearance of pathogen strains with beneficial... 

Cover photograph 1997 Norbert Wu/www.norbertwu.com. The antarctic red macroalga, Phyllophora antarctica, being held by the sea urchin, Sterchinus neumayeri, in a mutualistic relationship mediated by chemical and physical defenses. See Amsler, C.D., McClintock, J.B., and Baker, B.J., Mar. Ecol. Prog. Ser., 1999, 183, 105, and Chapter 7 in this volume. 

Mutualism is an obligatory relationship between two populations that benefits both. A mutualis-tic relationship requires close physical proximity it is highly specific, as one member cannot be replaced by another related species. A typical example is that of flowers and insects. Insects benefit by obtaining nectar from the flowers, and the plants benefit by being pollinated in the process. In some cases, the mutualistic relationship has become so close that the species involved are no longer... 

Finally, another potential interplay between UVR and viruses occurs when they coexist with their host in a type of mutualistic relationship, where the nucleic acid of the virus is integrated in the genome of the host and is replicated with it (lysogenic state). Ultraviolet C radiation produced by germicidal lamps (max. at 254 nm) has normally been used, among other stressors, to induce the shift from lysogenic to lytic state in a complex mechanism involving the DNA repair SOS system of the host [93]. However, natural or simulated solar UVR seems not to be very efficient in this process [94,95]. 

More recently, Rieper (1976) showed that the growth of a fraction of the bacterial population in the Schlei Fjord (Baltic Sea) is enhanced by actively growing cells of Chlorella spp., whereas other bacteria are inhibited by the same algae at the termination of their spring bloom (Fig. 4). In the late summer a symbiotic or mutualistic relationship exists between other bacteria and the alga Microcystis aeruginosa. 

Essential oils often are important as synomones (compounds that are of benefit to both the sending and receiving organism) in mutualistic relationships between plants and animals (especially insects). Synomones are especially important for pollination and fruit and seed dissemination. 

Several esters of hydroxy fatty acids (such as 3-acetoxy fatty acids) are involved in mutualistic relationships of some plants (such as those of the genus Krameria, Kramericeae) and their pollinating species. D-3-Hydroxydecanoic acid has fungicidal properties (Seigler, 1983). 

Mycorrhiza Mutualistic relationship between a fungus and a plant (tree or crop) wherein the plant gains access to limited soil nutrients from the fungus and the fungus gains energy from the plant. 

Approximately 80% of terrestrial higher plants are involved in mutualistic relationship with mycorrhizal fungi (Smith and Read, 1997 Pamiske, 2008). These interactions, which played a cmcial role for land colonization by plants (Brundrett, 2001), are essential for plant mineral nutrition (Smith et al, 2003). Some evidence indicates that mycorrhizas also have a relevant role in water up-take (Ebel et al, 1994), soil organic matter exploitation (Hodge et al,... 

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