BSC 314 Lecture Notes - Lecture 47: Sulfur Dioxide, Sulfur, Basidiomycota
27 Jun 2018
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Ecology of Fungi
Wherever there is moisture, moderate temperatures, and a supply of organic food there
are fungi. Since they digest their food outside of their bodies, they literally live within
their food supplies. When the area around them is depleted, they grow into a new
supply. They occur worldwide, although there may be more taxa in the tropics—an
assertion that is difficult to support because while there are an estimated 1.5 million
species of fungi, less than 10 percent of them have been described. About 500 species
are marine; the rest are terrestrial with several thousand described symbionts and plant
and animal pathogens.
Fungi usually are the primary decomposers in their natural habitats and are capable of
digesting a wide array of organic materials—including, unfortunately, some substances
of economic importance to humans. Most are saprobes, but some, like their animal
relatives, attack living prey, a notorious example being the fungus that sets hyphal
traps, ensnares and then digests nematodes. Many fungi are parasitic and the major
pathogens of many crop plants such as corn and wheat.
Symbiotic Relationships
Two important symbioses involve fungi: the mycorrhizae that occur on the roots of
almost all vascular plants and the lichens that have evolved entirely different body forms
from those of their symbionts.
Mycorrhizae
Fungi and the roots of almost all vascular plants form mutualistic associations
calledmycorrhizae (singular, mycorrhiza). The fungus gets its energy from the plant, and
the plant acquires an efficient nutrient absorbing mechanism—the actively growing
hyphae that penetrate regions of the soil untapped by root hairs. Phosphate uptake
especially is increased when mycorrhizae are present.
Two general types of mycorrhizae occur, differentiated by whether the hyphae
livewithin the cortical cells of the roots or remain outside the
cells: endomycorrhizae(endo = within; myco = fungus; rhizae = roots)
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Document Summary
Wherever there is moisture, moderate temperatures, and a supply of organic food there are fungi. Since they digest their food outside of their bodies, they literally live within their food supplies. When the area around them is depleted, they grow into a new supply. They occur worldwide, although there may be more taxa in the tropics an assertion that is difficult to support because while there are an estimated 1. 5 million species of fungi, less than 10 percent of them have been described. About 500 species are marine; the rest are terrestrial with several thousand described symbionts and plant and animal pathogens. Fungi usually are the primary decomposers in their natural habitats and are capable of digesting a wide array of organic materials including, unfortunately, some substances of economic importance to humans. Most are saprobes, but some, like their animal relatives, attack living prey, a notorious example being the fungus that sets hyphal traps, ensnares and then digests nematodes.
