The document provides an introduction to the Basidiomycota, including: - Basidiomycota produce sexual spores (basidiospores) on basidia and often form distinctive fruiting bodies (basidiocarps). - Some Basidiomycota like Armillaria ostoyae can form extensive underground networks of mycelium over large areas through dikaryotic growth. - Common mushrooms often emerge in circles known as fairy rings from the expanding mycelial networks. - The document then covers the classification, life cycles, and importance of key groups like rusts and smuts, which include major plant pathogens.

1. M. BARAKAT
2016

2. INTRODUCTION TO THE
BASIDIOMYCOTA
 The Basidiomycota are those organisms
that produce sexual spores (basidiospores)
on basidia often these are borne on
distinctive basidiocarps or basidioma. The
phylum typically has an extended
dikaryophase in which the distribution of
two nuclei to the daughter cells is facilitated
by the formation of a clamp connection,
which is similar to the crozier of the
Ascomycota.

3.  The most notable difference between the
ascomycotes and basidiomycotes is the extended
dikaryotic phase of some of the basiomycotas.
The dikaryon can grow for many years and extend
over many acres. For example, a mycelium of
Armillaria ostoyae, the root rot fungus, covers
about 2,200 acres in the Blue Mountains of
Oregon, making it one of the largest organisms on
earth (confirmed by DNA fingerprinting). Also,
given average growth rates for this species, a
mycelium that large would have to be about 8,000
years old.

6.  The successful mycelium that begins to grow from
a basidiospore is haploid, but likely encounters
another haploid filament fairly quickly. Thus, the
dikaryotic mycelium grows as an expanding circle.
The mycelium also feeds on all available organic
matter and nutrients during its expansion. Thus,
the center of the circle becomes played out, and
the hyphae die. So, older dikaryotic mycelia
expand as a ring, which also is the source of the
basidiocarps. Thus, common mushroom
basidiocarps often emerge in a circle, sometimes
called a fairy ring.

7.  I once had someone call me up about a "mushroom
problem" in his yard. He had mushrooms come up
every year, even though he went out faithfully and
picked them before they could shed their spores.
 I found the fundamental misunderstanding of the
nature of the fungal organism to be very amusing.
 I responded that trying to rid himself of mushrooms
by picking them was like trying to kill an apple tree by
picking the apples.
 I tried gently to convince him that the were not pests
and even served to help his lawn. Unfortunately, he
took a very different message from the one that I
intended.
 I discovered a year later that he had covered his lawn
with fungicide.

10. Life Cycle of (Ustilago maydis).
The smuts have a relatively simple life cycle
compared to that of the rusts (above). A dikaryotic
filament is formed from the fusion of two haploid
spores (spor- ida).
The dikayotic fila- ment infects the host plant (Zea
mays, in this case) and proliferates. Smutted ker-
nels become enlarged and tumor-like.
Fusion of hap- loid dikaryonuclei occurs and then
the kernel be- comes filled with black dip- loid
teliospores. These germinate, undergo mei- osis,
and form haploid sporida.

11.  The basidiomycote fungi range from common
mushroom forms to some of the world's most
important plant pathogens.
 The rusts (Subphylum Urediniomycotina, and
smuts (Subphylum Ustilagomycotina,are the
main groups of plant pathogens, some of
which are of major economic importance.
 The rusts (e.g. wheat rust and white pine
blister rust) alternate between two hosts and
have 5 different kinds of spores in their life
cycles.
 In the case of Puccinia graminis, karyogamy
occurs in the teliospore after which it
undergoes meiosis.

14.  Upon germinating, the haploid filament has four cells,
each of which has one of the meiospores and
releases them as basidiospores.
 After landing on an appropriate host (in this case a
barberry plant), the haploid basidiospore germinates
and begins to grow in the leaf tissue.
 The mycelia of the different mating types develop
clusters of spermogonia and receptive flexuous
hyphae (functional female).
 Fusion of spermagonia and receptive hyphae yield
dikaryotic hyphae, which produce chains of asexual
spores (aeciospores) within aecia.
 The aeciospores germinate if they land on an
appropriate grass (e.g. wheat). Then, the dikaryotic
hypha grows through the wheat, generally killing the
plant.

17.  They erupt on the sides of the infected wheat
stalks with orange-red uredeniospores in uredinia.
 These spores can infect more wheat, which in a
monoculture, can lead to the loss of the entire
crop very quickly. As the wheat plant is dying,
 the dikaryotic filament makes a different kind of
spore, a teliospore. This is the spore that can
remain in the soil, over winter, and then produce
basidiospores in the spring [See the life history
of Puccinia,.
 The smuts (e.g. corn smut and oat smut) infect
single hosts and have much simpler life histories.
However, they are no less devastating to the
crops that they infect.

18.  The Basidiomycotina is the most diverse
subphylum in the Basidiomycota, and the taxa
include common tree ears. jelly fungi, fairy clubs,
bracket fungi, puffballs, gill mushrooms, and
polypores.
 Typically, they can be differentiated on the basis
of their basidiocarps, which show great disparity
in form.
 In general, the basidiospores are the dispersive
spores and they are launched by hydrostatic
pressure between the sterigma and the
basidiospore on the basidium. In these cases,
they are called ballistospores.

19.  However, others have adopted different strategies.
Phallus, for example, emerges as a typical
mushroom, but the cap becomes deliquescent
(gelatinous) with the basidiospores embedded in
the gel. The cap also begins to emit the odor of
rotting meat. Flies that are attracted to the odor
get spores caught on their feet and bodies. Then,
being flies, they might go to feed on dung or
rotting organic matter, perfect growth media for
Phallus.
 Others, like the puffballs, form basidiocarps that
do not open to the outside. The inside of puffball
undergoes autolysis and forms a mass of loose
spores that are shed in puffs when the outer
covering (peridium) is touched.

20.  A single giant puffball can harbor millions of
basidiospores, and the mycelium can
produce several each year for the life of the
mycelium (For the sake of argument, say 10
years). That would be more spores from one
organism than all of the people on earth.
Yet, it might replace itself with only one or
two successful mycelia. This mantra of
"many try, few succeed" is the basis of
natural selection.

21.  Many of the basidiocarps are strikingly beautiful, and
some of them are quite tasty. The polypore, Boletus
eduli, is sometimes called the King of Mushrooms
because of its flavor and texture.
 The champignon, Agaricus bisporus, is the most
common table mushroom in the US, and almost half of
them are grown in Pennsylvania. Hunting for wild edible
mushrooms can be fun and rewarding; however, many
basidiocarps are poisonous, and a few are deadly.
 The Avenging Angel (Amanita phalloides) produces very
toxic alkaloids, such as phalloidine and α-amanitine,
which in sufficient concentrations, can destroy a healthy
liver over a period of three days. Only a liver transplant
can save the unlucky diner who mistakes Amanita
phalloides for Amanita caesarea. Indeed, the alkaloids
are so dangerous that they can move from one
mushroom to another if poisonous and nonpoisonous
mushrooms are put together in the same basket.

22. SYSTEMATICS OF THE
BASIDIOMYCOTA
 Like the taxonomic system of the Ascomycota, the
Basidiomycota has seen important reexamination
of many traditional associations and taxa. The
phylum is comprised of three major monophyletic
groups according to molecular, ultrastructural, and
biochemical evidence (Boeckhout et al. 1993,
1995; Fell et al. 1995; McLaughlin et al. 1995;
Prillinger et al. 1990; Swann and Taylor 1993,
1995; Wells 1994; Wolters and Erdman 1986;
Knudson 1995; and Hibbet et al. 1997).

23.  The Urediniomycotina (=Teliomycotina) represent the
oldest separation and are sisters to the rest of the
basidiomycete fungi (Ustilagomycotina +
Basidiomycotina). That relationship has been
confirmed by the SSU and LSU r-RNA analyses of
Lutzoni et al. (2004) and rpb2 and tef1 phylogenies of
Matheny et al. (2007). As with other groups which
have parasites as their most "primitive" forms, we
have reservations about claims that place the
complex parasitic taxa of the Urediniomycotina at the
root of the tree of the Basidiomycota. With this
reservation we use a system which is a modification
of Knudsen (1995) with 3 subphyla, 4 classes, and 34
orders.

25. LITERATURE CITED
 Adl, S. M., A. G. B. Simpson, M. A. Farmer, R. A. Andersen, O. R. Anderson, J. R. Barta,
S. S. Bowser, G. Brugerolle, R. A. Fensome, S. Fredericq, T. Y. James, S. Karpov, P.
Kugrens, J. Krug, C. E. Lane, L. A. Lewis, J. Lodge, D. H. Lynn, D. G. Mann, R. M.
McCourt, L. Mendoza, O. Moestrup, S. E. Mozley-Standridge, T. A. Nerad, C. A.
Shearer, A. V. Smirnov, F. W. Spiegel, and M. F. J. R. Taylor. 2005. The new higher level
classification of eukaryotes with emphasis on the taxonomy of protists. Journal of
Eukaryotic Microbiology. 52(5):399-451.
 Adl, S. A. G. B. Simpson, C. E. Lane, J. Lukes, D. Bass, S. S. Bowser, M. W. Brown, F.
Burki, M. Dunthorn, V. Hampl, A. Heiss, M. Hoppenrath, E. Lara, L. L. Gall, D. H. Lynn,
H. McManus, E. A. D. Mitchell, S. E. Mozley-Stanridge, L. W. Parfrey, J. Pawlowski, S.
Rueckert, L. Shadwick, C. L. Schoch, A. Smirnov, and F. W. Spiegel. 2012. The revised
classification of eukaryotes. Journal of Eukaryotic Microbiology. 59(5): 429-493.
 Alexopoulos, C. J. and C. W. Mims. 1979. Introductory Mycology. 3rd ed. John Wiley
and Sons. New York.
 Alexopoulos, C. J., C. W. Mims, and M. Blackwell. 1996. Introductory Mycology. 4th ed.,
John Wiley & Sons, New York.

26.  Boekhout, T., A. Fonseca, J.-P. Sampaio, and W. I. Golubev. 1993.
Classification of heterobasidiomycetous yeasts: characteristics and
affiliation of genera to higher taxa of heterobasidiomycetes. Canadian
Journal of Microbiology. 39: 276-290.
 Boekhout, T., J. W. Fell, and K. O’Donnell. 1995. Molecular systematics
of some yeast-like anamorphs belonging to the Ustilaginales and
Tilletiales. Studies in Mycology. 38: 175–183.
 Bold, H. C., C. J. Alexopoulos, and T. Delevoryas. 1987. Morphology of
Plants and Fungi. 5th Edition. HarperCollins Publishers, Inc. New York.
 Fell, J. W., T. Boekhout, and D. W. Freshwater. 1995. The role of
nucleotide analysis in the systematics of the yeast genera
Cryptococcus and Rhodotorula. Studies in Mycology. 38: 129-146.
 Hibbett, D. S., E. M. Pine, E. Langer, G. Langer, and M. J. Donoghue.
1997. Evolution of gilled mushrooms and puffballs inferred from
ribosomal DNA sequences. Proceedings of the National Academy of
Sciences USA. 94: 12002-12006.

27.  Hibbett, D. S., M. Binder, J. F. Bischoff, M. Blackwell, P. F. Cannon, O. E.
Eriksson, S. Huhndorf, T. James, P. M. Kirk, R. Lücking, T. Lumbsch, F.
Lutzoni, P. B. Matheny, D. J. Mclaughlin, M. J. Powell, S. Redhead, C. L.
Schoch, J. W. Spatafora, J. A. Stalpers, R. Vilgalys, M. C. Aime, A. Aptroot, R.
Bauer, D. Begerow, G. L. Benny, L. A. Castlebury, P. W. Crous, Y.-C. Dai, W.
Gams, D. M. Geiser, G. W. Griffith, C. Gueidan, D. L. Hawksworth, G.
Hestmark, K. Hosaka, R. A. Humber, K. Hyde, J. E. Ironside, U. Kõljalg, C. P.
Kurtzman, K.-H. Larsson, R. Lichtwardt, J. Longcore, J. Miądlikowska, A.
Miller, J.-M. Moncalvo, S. Mozley-Standridge, F. Oberwinkler, E. Parmasto, V.
Reeb, J. D. Rogers, C. Roux, L. Ryvarden, J. P. Sampaio, A. Schüßler, J.
Sugiyama, R. G. Thorn, L. Tibell, W. A. Untereiner, C. Walker, Z. Wang, A.
Weir, M. Weiß, M. M. White, K. Winka, Y.-J. Yao, and N. Zhang. 2007. A higher-
level phylogenetic classification of the Fungi. Mycological Research. 111: 509-
547. [C]
 Knudsen, H. 1995. Taxonomy of the basidomycetes in Nordic Macromycetes.
Symb. Bot. Ups. 30 (3):169–208.
 Lutzoni, F., F. Kauff, C. J. Cox, D. McLaughlin, G. Celio, B. Dentinger, M.
Padamsee, D. Hibbett, T.Y. James, E. Baloch, M. Grube, V. Reeb, V. Hofstetter,
C. Schoch, A.E. Arnold, J. Miadlikowska, J. Spatafora, D. Johnson, S.
Hambleton, M. Crockett, R. Shoemaker, G. Sung, R. Lucking, T. Lumbsch, K.
O’Donnell, M. Binder, P. Diederich, D. Ertz, C. Gueidan, K. Hansen, R. C.
Harris, K. Hosaka, Y-W. Lim, B. Matheny, H. Nishida, D. Pfister, J. Rogers, A.
Rossman, I. Schmitt, H. Sipman, J. Stone, J. Sugiyama, R. Yahr, R. Vilgalys.
2004. Assembling the fungal tree of life: progress, classification, and evolution
of subcellular traits. American Journal of Botany. 91(10): 1446-1480.

28.  Matheny, P. B., Z. Wang, M. Binder, J. M. Curtis,
Y. W. Lim, R. H. Nilsson, K. W. Hughes, V.
Hofstetter, J. F. Ammirati, C. L. Schoch, E.
Langer, G. Langer, D. J. McLaughlin, A. W.
Wilson, T. Froslev, Z-W. Yang, T. J. Baroni, M.
Fischer, K. Hosaka, K. Matsuura, M. T. Seidl, J.
Vauras, and D. S. Hibbett. 2007. Contributions of
rpb2 and tef1 to the phylogeny of mushrooms
and allies (Basidiomycota, Fungi). Molecular
Phylogenetics and Evolution. 43: 430-451.
 McLaughlin, D. J., E. M. Frieders, and Haisheng
Lü. 1995. A microscopist's view of
heterobasidiomycete phylogeny. Studies in
Mycology. 38: 91-109.

29.  Prillinger, H., C. Dörfler, G. Laaser, and G. Hauska. 1990. A contribution
to the systematics and evolution of higher fungi: yeast-types in the
basidiomycetes. Part III: Ustilago-type. Zeitschrift fur Mykologie. 56:
251-278.
 Scagel, R. F., R. J. Bandoni, G. E. Rouse, W. B. Schofield, J. R. Stein,
and T. M. C. Taylor. 1984. Plant Diversity, An Evolutionary Approach.
Wadsworth Publishing Co. Belmont, CA.
 Swann, E. C. and J. W. Taylor. 1993. Higher taxa of basidiomycetes: an
18S rRNA gene perspective. Mycologia. 85(6): 923-936.
 Swann, E. C. and J. W. Taylor. 1995. Phylogenetic perspectives on
Basidiomycete systematics: evidence from the 18S rRNA gene.
Canadian Journal of Botany.73(suppl. 1): S862-S868.
 Wells, K. 1994. Jelly fungi, then and now!. Mycologia. 86: 18–48.
 Wolters, J. and V. A. Erdman. 1986. Cladistic analysis of 5S rRNA and
16S rRNA secondary and primary structure - the evolution of eukaryotes
and their relation to Archaebacteria. Journal of Molecular Evolution.
24:152-166.