Summary of Autopolyploidy and Allopolyploidy

1. Submitted by-
Bhanumati dhinda
ADM NO-50c/15
2nd yr bsc ag
Summary of Autopolyploidy and
Allopolyploidy
SUBMITTED TO:
DR.KAUSHIK
KUMAR PANIGRAHI
ASST.PROFESSOR
GENETICS

2. Polyploidy
Presence of more then two genomes
in an individual is koown as polyploidy.
There are 2 main kinds of polyploidy,
I. Autopolyploidy.
II. Allopolyploidy.

3. Autopolyploidy-
This occur when an individual has more than
two sets of chrompsomes(4n),all derived from an
original species(2n).
Word derivation-
•Auto-self
•Poly-many
•Ploid – fold
So autopolyploidy means having many
cromosome of their self(their species)

4. HOW DOES THIS OCCUR
•During normal meiosis the
chromosomes number is reduced by
half(2n to n)
•In auto polyploid a failure in meiosis
causes the chromosomes to fail to
separate,resulting in gametes with
twice as many chromosome as
normal(2n).
•If this organism fertilise itself than
its offsprings will be tetraploid(4n)

6. Autopolyploids may have three(triploid),
four(tetraploid),five (pentaploids) six(hexaplo),
seven(heptaploid),eight(octaploid), or more copies
of the same genome.
Of these triploids and tetraploids have been
studied in considerable details due to their
impotance in crop movement.

7. Advantage of autopolyploidy
1.Much higher levels of heterozygosity than do
their diploid progenitors due to polysomic
inheritance.
2.Increase in general vigour and size(gigantism)
3.Larger effective population sizes than diploids,
allowing selective processes to be much more
effective relative to random genetic drift.
4. Much higher levels of heterozygosity than do
their diploid progenitors due to polysomic
inheritance

8. Disadvantages of autopolyploidy:
(1) prolongation of cell division time
(2) increase in the volume of the nucleus
(3) increase in the number of chromosome
disjunctions during meiosis
(4) genetic imbalances
(5) interference with sexual differentiation when
the sex of the organisms is determined by either
the ratio between the number of sex
chromosomes and the number of autosomes (as
in Drosophila), or by degree of ploidy (as in
Hymenoptera)

9. It have limited application in crop improvement
Triploid watermelons are produced,these produce
only rudimentary seed which are not objectionable
when chewed.
Triploid sugarbeets produce larger root and more
sugar per unit area.
An autoploid clone of tea(TV29) has been released
which have higher leaf yield and quality is good.
Autoploid turnip,cabbage are also release.
APPLICATION

10. Musa barbisiana (diploid)
Musa acuminata
(triploid).contain less
seed.

11. watermellon Cabbage
patatostrawberry

12. Allopolyploidy
This occur when two different species
contribute to a polyploid hybrid.
•Word derivation
Allo-other
Poly-many
Ploid-fold(chromosome)
Allopolyploid-having many chromosome from
others

13. Origin of allopolyploids:
 Natural allopolyploids most likely originate through
chromosome doubling of F1 hybrid produced by chance
through natural hybridization between two distinct
species of the same genus or from different genera.
 Experimental production of allopolyploids is achieved
through chromosome doubling of F1 hybrid with the
help of colchicine.
 Such allopolyploids are often called synthetic
allopolyploids. The synthesis of allopolyploids involves
two steps.
1. Production of F1 hybrids by crossing two distinct
species a
 2. Chromosome doubling of such F 1 hybrids. The
man made cereal Triticale is an example of synthetic
allopolyploid.

15. Application in crop
improvements
Allopolyploidy is much more common in nature
than autopolyploidy. About 80% of all land plants
may be allopolyploids
The common bread wheat(T.aestivum) is a
Allohexaploids.
Nicotiana tabacum and N rustica are
allotetraploids.
Several Brassica species such as
B.juncea,B.napus,B.carniata are allo
tetraploids.Raphano brassica is a promising
synthetic allopolypliods

16. Raphanus brassica
Allohexaploid wheat