Mating system in Bsdiomycets a research work done by reading many articals and research paper and books

2. MATING SYSTEMS IN
BASIDIOMYCETES
Tayyaba Amir
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3. CONTENTS
 Introduction
 Mating types
 Homothallism
 Heterothallism
 Multiple alleles
 Functions of A and B loci.
 Structure of mating type factors.
 Conclusions
 Reference.
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4. INTRODUCTION
 Mating systems of basidiomycetes are the possible ways
in which basidiomycetes can interect with each other in
order for reproduction.
 For example: Mashrooms..
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5. BASIDIOMYCETES
 Any of a group of higher fungi have septate hyphae
and spore borne on basidium ,that include rust,
smut, mushrooms and puffballs.
Kingdom: Fungi
Phylum: Basidiomycota;
Scientific name: Basidiomycota
Rank: Phylum
Higher classification: Dikarya
Division: Basidiomycota
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6. MATING TYPES
 In biology, mating (or mateing in British English) is
the pairing of either opposite-sex or organisms,
usually for the purposes of sexual reproduction.
 In basidiomycetes there are two basic mating
systems
1. Homothallism
2.Heterothallism
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7. HOMOTHALISM
 Homothallic refers to the possession, within a single
organism, of the resources to reproduce sexually; i.e.,
having male and female reproductive structures on the
same thallus. The opposite sexual functions are performed
by different cells of a single mycelium.
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8. HOMOTHALLIC SYSTEMS
 Three types of homothallic behaviour may be
distinguished, namely primary, secondary and unclassified
homothallism.
Primary
homothallism
Secondry
homothallism
Unclassified
homothallism 8

9. PRIMARY HOMOTHALLISM
 A single basidiospore germinates to form a
mycelium, which soon becomes organized into
binucleate segments bearing clamp connections at
the septa. There is no genetic distinction between
the two nuclei in each cell, and this mycelium is
capable of forming fruit bodies.
 For example
Coprinuss terquilinus
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10. SECONDARY HOMOTHALLISM
The basidia
bear only
two spores,
but the
spores are
heterokaryot
ic.
After meiosis
two nuclei
enter each
spore and a
mitotic
division may
follow.
On germination, a
single spore
forms a dikaryotic
mycelium with
clamp
connections,
capable of
fruiting.
Occasional spores, on
germination, give rise
to non-clamped
mycelia, and fruiting
occurs only if these
are paired in certain
combinations, showing
that the fungus is
basically heterothallic.
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11. UNCLASSIFIED HOMOTHALLISM
 Both of the cases can be found in them. First half
as one type next like the other vice versa. Or may
be some other unspecified system.
 For example
Agaricuscampestris
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12. HETEROTHALLISM
 Heterothallic species have sexes that reside in different
individuals. The term is applied particularly to
distinguish heterothallic fungi, which require two
compatible partners to produce sexual spores, from
homothallic ones, which are capable of sexual reproduction
from a single organism.
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14. HETEROTHALLIC SYSTEM
 Amongst the remaining 90% of the basidiomycota
reported to be heterothallic, we can distinguish bipolar and
tetrapolar conditions.
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15. 15

16. BIPOLAR
 When mycelia obtained from single spores from any one
fruit body are mated together, dikaryons are formed in
half the crosses. This can be explained on the basis of a
single gene (or factor) with two alleles.
 For example
 Coprinuscomatus ,Piptoporusbetulinus ,Uredinales,
Ustilaginales
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17. TETRAPOLAR
 Incompatibility is controlled by two genes (factors), with
two alleles at each locus. Because two separate factors
are involved, the genetic basis is termed bifactorial.
Thus we can denote the two genes as A and B and their
two alleles as A1, A2 and B1, B2, respectively.
 For examle
Coprinuscinereus ,Schizophyllum commune
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18. 18

19. MULTIPLE ALLELS
 A large number of alleles is present in a population
representing the species as a whole, instead of the single
pair of alleles at each locus present in any one dikaryotic
mycelium. Suppose that a second fruit body had the
composition (A3B3 þ A4B4), then all the four kinds of
spore it produced, A3B3, A3B4, A4B3 and A4B4 would
be compatible with all the spores of the original fruit
body, on the assumption that the essential requirement
for fertility is that in any cross both alleles should differ
at both loci.
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20. FUNCTIONS OF THE AAND B LOCI
Table. Functions of the A and B loci in Schizophyllum commune and Coprinus cinereus. The
functions operate only if there are different specificities at the A and B loci.
Locus Function
A-regulated Pairing of nuclei in dikaryon
Initiation of clamp cell formation
Synchronized nuclear division
Septation
B-regulated Nuclear exchange between monokaryons
Septal dissolution and nuclear migration
Peg formation and clamp cell fusion
Pheromone production
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21. .STRUCTURE OF THE MATING TYPE
FACTORS
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22. CONCLUSION
 Basidiomycetes are mushroom fungi. They are heterothallic
and homothallic. The mating system becomes a bit complex
by compatibility or non-compatibility of basidial body.
 So it require proper signal for stimulating the mating genes;
basically four gene (A,B,α and β) which govern mating pattern
of this group of fungi.
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23. REFFERENCES
 https://www.merriam-webster.com/dictionary/basidiomycete.
 Thielke, C. (1982). Meiotic divisions in the basidium. In Basidium and
Basidiocarp: Evolution, Cytology, Function and Development, ed. K.
Wells & E.K. Wells. New York: Springer-Verlag, pp. 7591.
 Sun, N.C. & Bowen, C.C. (1972). Ultrastructural studies of nuclear
division in BasidiobolusranarumEidam. Caryologia, 25, 243247.
 Swann, E.C. & Taylor, J.W. (1993). Higher taxa of basidiomycetes: an
18S rRNA gene perspective. Mycologia, 85, 923936
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