be concentrated when mushrooms are dried or stored in a container.6,14
Ecological roles
of odors Odors can be divided into two
Figure 13A. The strength of the bleachy odor in Inocybe geophylla, and many other Inocybe species, is increased when the stem and cup are crushed. Photo Joseph Nuzzolese.
primary groups; those that signal and affect members of the same species, and those that signal and affect members of different species. Mushrooms give off many odors that are not detectable to our noses but are sensed by plants, animals, insects, bacteria, and other fungi sharing their habitat. Tese volatiles are thought to be a “universal language” in the complex intraspecific and interspecific interactions that help organisms survive.5
Intraspecific
Figure 11. Mycetinis scorodonius gets its specific name from scorodon, the ancient Greek and Roman word for garlic. Photo Andrus Voitk.
Figure 13B. Mycena alcalina complex is also easily recognized for their bleachy odor. Photo Andrus Voitk.
anywhere. And still others may easily detect odors but may not be able to name it, especially if they have not experienced the odor before.12
communicative interactions may be cooperative, competitive, defensive, and pathogenic in nature, but how volatiles are sensed at the cellular level in organisms lacking olfactory organs is not yet fully understood.1,15
Volatiles and interspecific
development Volatiles are important in the early
Tese comments should
not discourage you from using odor as an aid to mushroom identification. Instead, they should help you understand that we do not all sense odors the same and allowances should be made for varying interpretations of a smell. Further complicating mushroom
Figure 12. Cortinarius traganus, commonly found in boreal forests, has an odor resembling over-ripe pears or apples, an important distinction when separating it from its lookalike C. camphoratus. Photo Jim Cornish.
48 FUNGI Volume 14:4 Fall 2021
identification using odor is intraspecific odor variability caused by environmental factors. Te day-to-day strength of any mushroom odor may vary depending on air temperature and humidity as well as nutrient availability, soil temperature, oxygen availability, pH, soil moisture content of the substrate. Odor can also differ within a specimen, being weaker or stronger in either the cap, stem, or gills. Since odor biosynthesis is a resource- consuming process, some mushrooms synthesize or strengthen their odors on demand13
when, for example,
mushrooms are crushed (Fig. 13A). As experienced collectors know, odors can
development of mycelia. When fungal spores germinate, their one or two germ tubes continuously branch to form simple independent mycelia that grow radially through the substrate in search of organic matter. Initially, mycelia emit volatiles to prevent their hyphae from fusing with each other, or with mycelia of other fungi, especially harmful ones. Following initial growth stages, genetically identical mycelia then secrete volatiles to help them locate one another and fuse. What were once individual mycelia becomes a colony capable of transporting nutrients, water and volatiles throughout a complex interconnected network that may grow to be several hectares in area (Fig. 15).16,17
Cooperative
interactions Mushrooms and plants are known
to form complex partnerships. Below ground, hyphae and plant roots exude volatiles that diffuse through air pockets in soils and the detritus layer.18,19 Tis diffusion is an essential form of communication in the mycorrhization
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76
