Here at the PDIC we focus on the negative impacts of fungi,
bacteria, nematodes, and viruses on plant health and human well-being. This
tends to overshadow the fact that they do more good than harm in the grand
scheme of things. Since we deal mostly with fungi, I offer several for which we
should be grateful.
Saccharomyces cerevisiae helping in the kitchen. |
Mycorrhizal fungi at work, under the surface. Plant Pathology Department Slide Collection |
Mycorrhizae. When
we look at a plant, we don't usually think about the roots. Even when we do think
about roots, we usually forget that most plants partner-up with certain fungi
that enable them to better extract nutrients from soil. This association is
known scientifically as a "mycorrhiza" (plural
"mycorrhizae"), which is simply Greek for "fungus-root".
Other benefits have been ascribed to this relationship such as increased
resistance to root diseases and other stresses. There are two basic groups: the
ectomycorrhizae and the arbuscular mycorrhizae. The former are
characteristically associated with trees and form a fungal mantle on the
outside of the root, slightly modifying its structure and appearance. Often
these fungi produce mushrooms or puffballs (above or below ground) when it
comes time to reproduce. A good example is the small, reddish Russula mushroom we see popping up each
fall in our area. The arbuscular mycorrhizae form on both herbaceous and woody
plants, and are very inconspicuous. If you aren't a scientist dedicated to
plant roots in some way or another, you probably won't ever notice them. Do
appreciate them, though, as they are close collaborators with the plants we so
value and need.
Brown cubical rot of pine wood, caused by the fungus Meruliporia incrassata. Plant Pathology Department Slide Collection |
Wood decay fungi.
Yes, wood decay fungi are unwelcome when they invade living trees or our homes,
but we’d be in deep trouble without them. They are a critical cog in the carbon
cycle, degrading the cellulose and lignin components of wood. In fact, fungi
are the only organisms in the world that produce the enzymes necessary to break
down lignin. Without them we would be up to our eyeballs in woody debris. There
are a number of spin-off benefits, as well. For example, pulping using these
fungi will be better than current processes in terms of reducing both energy
use and chemical waste.
Fungi with medicinal
applications. We remember with gratitude the mold Penicillium, which brought about the antibiotic revolution. Apart
from the penicillins, the cephalosporin antibiotics can also be traced to a
fungal metabolite. The cholesterol-lowering drugs compactin and lovastatin are
derived from fungal fermentation, although other statin drugs are synthetic or
semi-synthetic. Traditional Chinese medicine makes use of a number of different fungi, some of which may find their way into the western pharmacopeia.
Agriculturally
important fungi. Several fungi such as Beauveria
bassiana and Metarhizium anisopliae
are used as biological insecticides. Some such as Trichoderma harzianum are found in biological fungicides. Also, an
important group of chemical fungicides, the strobilurins, were developed based
on a chemical found in the mushroom Strobilurus
tenacellus.
Farmed, or Farmer? |
Neocallimastix and company. Probably the most obscure group on
the list, it was only within the last forty years that these were recognized as
fungi and not protozoans. This includes genera with such names as Orpinomyces, Piromyces, and Neocallimastix, Once known as the "rumen chitrids", they
are better called "anaerobic gut fungi", "anaerobic zoosporic
fungi", or simply "anaerobic fungi". They work together with
bacteria and protozoans in the digestive systems of many kinds of herbivores to
break down the fibrous diet of these animals. They are found in the rumen of
animals such as sheep and cattle, but have also been found in deer, horses,
kangaroos, even rhinos and elephants. They do a better job than bacteria at breaking down lignocelluloses,
and their rhizoids can get through plant cuticles, which bacteria &
protozoans cannot penetrate. We really should be thinking of cows as farmers, responsible
for a large and diverse population of microbes that convert roughage into materials
that the cows can metabolize.
Strawberry jelly ingredients. Where does the citric acid come from? |
Read on to find out about Insects to Be Thankful For.